Ultra-Sensitive Room-Temperature Ammonia Detection Enabled by MEMS-Based 0D/1D/2D PA10Mo2 Nanocomposites

Ultra-Sensitive Room-Temperature Ammonia Detection Enabled by MEMS-Based 0D/1D/2D PA10Mo2 Nanocomposites | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Ultra-Sensitive Room-Temperature Ammonia Detection Enabled by MEMS-Based 0D/1D/2D PA10Mo2 Nanocomposites Ping Luo, Wenfeng Shen, Jin Zhang, Dawu Lv, Ruiqin Tan, Weijie Song This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6704267/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 06 Aug, 2025 Read the published version in Microchimica Acta → Version 1 posted 8 You are reading this latest preprint version Abstract In this study, a 0D/1D/2D Au/Polyaniline/MoS₂ (PA 10 Mo 2 ) hierarchical nanocomposite based on microelectromechanical systems (MEMS) was successfully synthesized via in situ chemical oxidative polymerization. The 0D, 1D, and 2D materials in the composite form a three-dimensional transport network; the surfaces of MoS₂, PANI, and Au promote gas diffusion through unsaturated bonds, polar groups, and high surface energy, respectively. The sensor fabricated from this composite exhibits response and recovery times of 69 seconds and 89 seconds, respectively, at room temperature for 1 ppm of ammonia, whereas those of pure PANI are 95 seconds and 156 seconds, respectively. Additionally, gold nanoparticles regulate the growth and distribution of PANI and MoS₂, increasing the active sites in the film from 12.82% to 45.87%. Moreover, the built-in electric field of the p-n heterojunction formed between PANI and MoS₂ drives the directional movement of carriers, optimizing carrier transport. When the ammonia concentration is 1 ppm, the sensor can achieve a response of 92.5%, and its theoretical minimum detection limit is 0.45 ppb. This work presents an innovative and efficient solution for ammonia sensing at room temperature, demonstrating significant potential in the fields of wearable electronic devices and human health monitoring. Ammonia sensor Polyaniline MEMS-based sensor Room-temperature MoS2 Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 1. Introduction Ammonia (NH₃) is an important biomarker, with abnormal concentrations in human breath (>2 ppm), being closely associated with diseases such as liver and kidney dysfunction and Helicobacter pylori infection [1–3]. This makes it a significant target for non-invasive diagnosis [4]. Traditional ammonia detection techniques, such as blood sampling and biopsy, are often painful and time-consuming for assessing liver and kidney function. Gas chromatography, on the other hand, relies on laboratory equipment and cannot meet the demands of point-of-care diagnostics for portability, low cost, and rapid response [5]. Chemiresistive gas sensors have garnered extensive research attention owing to their low cost and flexibility, including wearable sensors and breath analyzers based on polyaniline [7], metal oxides [8, 9], and two-dimensional materials [11]. Although traditional metal oxide semiconductor (MOS) sensors can achieve high responses at elevated temperatures (usually 200 ~ 400°C), they suffer from significant drawbacks including high power consumption, which is incompatible with the low-power requirements of portable devices [12], and poor selectivity due to their broad-spectrum response, making them highly susceptible to interference from water vapor, ethanol, and other substances in complex gas environments [13]. These limitations have prompted researchers to explore new room-temperature sensing materials actively. In recent years, room-temperature ammonia sensing materials with low power consumption and high selectivity have become a research focus. Polyaniline (PANI), featuring a unique proton-doping mechanism, tunable conductivity, and room-temperature operation, has garnered significant attention. PANI's sensing performance hinges on redox state changes: upon exposure to NH₃, deprotonation of its protonated imine groups (= NH⁺=) by NH₃ molecules reduces conductivity [15]. However, Pure PANI-based sensors face limitations, including high detection limits (ppm-level), slow response and recovery times, and humidity sensitivity. To address these, recent strategies involve material composites [16]. Introducing 2D transition metal dichalcogenides (e.g., MoS₂) to form heterostructures enhances active site density and charge transport [18, 19]. While noble metal nanoparticles (e.g., Au) reduce reaction energy barriers through catalysis and increase the active reaction sites. The PANI matrix enables room-temperature operation and synergizes with other components, providing a novel solution that balances sensitivity, selectivity, and stability. Based on these findings, this study proposes, for the first time, a ternary hierarchical structure of PA 10 Mo 2 integrated on a MEMS chip. The two-dimensional characteristics of MoS 2 increase the effective number of gas-material interaction sites and form a p-n heterojunction with PANI to enhance charge carrier mobility. At the same time, the catalysis from Au nanoparticles improves the kinetic processes of NH₃ adsorption and desorption. Meanwhile, the advantages of PANI for room-temperature operation are maintained. Experimental results demonstrate that the sensor exhibits high sensitivity and rapid recovery characteristics at room temperature, with a response value nearly eight times higher than that of pure PANI. This work not only provides a batch-integrable sensing solution for wearable electronics and Internet of Things nodes but also offers theoretical insights into the design paradigm of multi-dimensional nanocomposites. 2. Experimental section 2.1 Materials Molybdenum disulfide (MoS₂, 99.9%, particle size 12 ~ 16 µm), ammonium persulfate (APS), hydrochloric acid (HCl, 36 ~ 38%), ammonium hydroxide (NH₄OH, 25.0 ~ 28.0%), aniline (≥ 99.0%) Gold(III) chloride (AuCl₃, 98%), MEMS micro-hotplate(CWSG-W200), deionized water (DI). 2.2 Materials characterizations and sensing performance tests To investigate the static micro-morphology of the fabricated thin films, observations were conducted using a high-resolution scanning cold field-emission electron microscope (Regulus 8230 SEM). The chemical element distribution within the films was determined through energy-dispersive X-ray spectroscopy (EDS). Crystal structure characterization was performed using a high-power rotating-target polycrystalline X-ray diffractometer (XRD, D8 DISCOVER, Germany). Molecular structure analysis was carried out via an intelligent Fourier transform infrared spectrometer (FT-IR, NICOLET 6700, USA). Elemental composition and chemical states were analyzed using X-ray photoelectron spectroscopy (XPS, AXIS SUPRA, UK). Notably, powder samples were exclusively used for XRD analysis, while all other characterizations were performed on MEMS sensor films. 2.3 Preparation method of PA 10 Mo 2 gas-sensitive material The precursor solution was prepared by first mixing aniline with 2 mL of 1 M hydrochloric acid (HCl), followed by sequential addition of molybdenum disulfide (MoS₂) at varying concentrations (0.003 M, 0.09 M, 0.15 M, 0.21 M, 0.3 M). The precursor solution was subjected to 2-hour ultrasonic treatment and subsequently quiescently aged for 1 hour at 0 ~ 2°C. Following this, 48.6 µL of 0.33 M auric chloride (AuCl₃) solution was dropwise added under continuous ultrasonication at 0°C for 10 minutes. A vertically suspended MEMS chip was immersed in the resultant solution and maintained at 0 ~ 2°C for 30 hours. During the reaction, the solution color transitioned from light brown to dark green, indicating polymerization of aniline monomers into polyaniline (PANI). After the reaction, the chip was retrieved, rinsed three times with deionized water, and dried at 60°C. The final products comprised gold/polyaniline/molybdenum disulfide (Au/PANI/MoS₂) composites with varying MoS₂ loadings, designated as PA 10 Mo 1 , PA 10 Mo 2 , PA 10 Mo 3 , PA 10 Mo 4 , and PA 10 Mo 5 based on MoS₂ concentration. For comparative analysis and mechanism investigation, control samples of pure polyaniline (PANI) and gold-aniline (Au-PANI) synthesized through analogous protocols were labeled as PANI and PA 10 , respectively. 2.4 Sensor fabrication and gas-sensing measurement Upon completion of thin-film fabrication, the sensor chip deposited with the thin film was encapsulated in a TO-5 standard semiconductor package through ultrasonic gold wire bonding technology (WE-2013, Shenzhen Weichen Technology Co., Ltd., in Fig. S1 (a), followed by integration into a sensor testing module (CSMS6V4-CR10K, manufactured by CS-MicroSensor Co., Ltd., Ningbo, as displayed in Fig. 1 ) for subsequent gas sensing performance evaluation. The gas sensing characteristics of the sensor were systematically analyzed by a static gas sensor intelligent detection system (QX-G100M, Qiwei Sensor Technology Co., Ltd., Ningbo; depicted in Fig. 1 ), which facilitates real-time transmission of sensor resistance data to a computer via Bluetooth/USB interfaces at a sampling rate of 10 Hz. Environmental conditions during testing were precisely regulated using a climate chamber (DHTHM-27-20-p-sd, Duoao Testing Equipment Co., Ltd., Shanghai; refer to Fig. S1 (b)) for temperature and humidity control. Ammonia test gas was generated through the saturated vapor pressure method, while certified gas standards including nitrogen dioxide (NO₂), sulfur dioxide (SO₂), carbon dioxide (CO₂), ethanol (C₂H₅OH), acetone (C₃H₆O), formaldehyde (CH₂O), and methane (CH₄) were supplied by Hangzhou New Century Specialty Gases Co., Ltd. The gas-sensing performance metrics encompassed six critical parameters: response value, limit of detection (LOD), sensitivity, repeatability, selectivity, and long-term stability. The response value (S) is defined by the equation: \(\:S\:=\:({R}_{g}\:-\:{R}_{a})/{R}_{a}\:\times\:\:100\text{%}\) , where Ra and Rg denote the electrical resistance values measured in ambient air and target gas atmosphere, respectively. The response time is defined as the duration required for the sensor to attain 90% of the total resistance variation upon exposure to the target gas, whereas the recovery time represents the period necessary for the resistance to return to 90% of its baseline value after re-exposure to air. Results and discussion 3.1 Characterization of materials Before characterization, the ratio of MoS₂ to PANI in the composite was optimized according to the response values. As shown in Fig. S3(a), PA 10 Mo 2 exhibited the highest response among all samples at both low (1 ppm) and high (10 ppm, 20 ppm) ammonia concentrations, indicating that MoS₂, Au, and PANI synergistically enhanced the ammonia response at this ratio. As the MoS₂ content increased, agglomeration intensified, reducing the gas-sensing advantages brought by MoS₂ itself. Therefore, unless otherwise specified, the composite material referred to hereafter is PA 10 Mo 2 . As shown in Fig. S2 and Fig. 2 (a), the MEMS-based sensor features a 160 µm × 160 µm suspended platform. Fig. S4(a) and S4(b) present SEM images of PANI oxidized by APS and PA 10, respectively. When Au³⁺ acts as the oxidizing agent, it gets reduced to form nanospheres that deposit on the Pt electrode (570 ~ 640 nm in diameter), while PANI forms nanorods covering the MEMS surface. As shown in Fig. 2 (b) and (c), PANI exhibits a rod-like morphology with a width of 30 ~ 40 nm and a length ranging from 150 to 250 nm, densely and uniformly distributed on the MEMS chip. In Fig. 2 (a), the circled part represents MoS₂, which, as shown in Fig. 2 (d), exhibits a 2D multi-layer flake structure. Au accumulates at MoS₂ edges, and its nanoparticles attract aniline monomers, thereby promoting the polymerization growth of polyaniline from the edges inward on the surface of MoS₂. As illustrated in Fig. 2 (d) and (e), PANI is evenly distributed on and between MoS₂ layers. PANI grows vertically on MoS₂, providing more reaction sites with ammonia and shortening the gas transport path. Additionally, PANI connects MoS₂ and Au, forming a fishnet-like structure that increases the number of gas-material reaction channels. Besides aggregating at MoS₂ edges, Au is adsorbed onto interdigitated electrodes (Fig. 2 (f)). The high affinity among Au nanoparticles promotes the aggregation of PANI near the Pt electrode, leading to uniform distribution of PANI across the entire MEMS chip [20]. The Au particle size, around 520 ~ 570 nm, is smaller than that of PA 10 . This is because MoS₂ promotes Au reduction and growth [21], enhancing its catalytic activity. Additionally, the EDS results show that Au is predominantly deposited on the Pt electrode, while Mo, S, C, N, and O are uniformly distributed across the chip (Fig. 3 (g)). The existence of C, O, and N on MoS₂ in Fig. 3 (f) indicates the presence of PANI on MoS₂. These findings confirm the successful in-situ oxidative polymerization of a MEMS-based 0D/1D/2D ternary multi-level PA 10 Mo 2 thin film co-modified by Au and MoS₂ on the MEMS chip. The XRD analysis elucidated the crystallographic characteristics of PANI, PA 10 and PA 10 Mo 2 . As illustrated in Fig. 3 (a), PANI exhibited a broad, low-intensity diffraction signal within the 2θ range of 15 ~ 30°, attributed to the (200) crystallographic plane of its emeraldine salt (ES) form, confirming its semi-crystalline nature. Notably, anomalous signals detected in this region originated from NH₄Cl crystals formed by the reaction between the oxidizing agent (NH₄)₂S₂O₈ and the acidic medium (Fig. S5(a)). For the PA 10 , distinct diffraction peaks observed at 38.2°, 44.4°, 64.6°, and 77.5° correspond to the (111), (200), (220), and (311) planes of Au, respectively, with peak positions aligning precisely with the JCPDS reference database (Card No. A26-1080-1). The XRD patterns of PA 10 Mo 2 retained the characteristic Au diffraction signatures while revealing additional peaks at 14.4°, 32.7° and 39.5°, which were indexed to the (002), (100), and (103) planes of hexagonal-phase MoS₂.All observed MoS₂ peaks exhibited minimal deviation from standard reference values (JCPDS 37-1492-33). Intriguingly, the absence of PANI-specific diffraction peaks in both PA 10 and PA 10 Mo 2 suggests structural reorganization during synthesis. This phenomenon likely stems from the dissociation of hydrogen-bonding networks within PANI chains, driven by the redox interaction between AuCl₃ and PANI. Specifically, Cl⁻ ions bind to protons on the polymer backbone, forming HCl and inducing oxidative restructuring of benzene rings. These molecular-level alterations provide a plausible explanation for the significantly elevated initial electrical resistance observed in PA 10 Mo 2 relative to pristine PANI and PA 10 [22]. FT-IR spectrum in Fig. 3 (b) revealed the chemical structures of pure PANI, PA 10 , and PA 10 Mo 2 . The broad band at 3446 cm⁻¹ and the peak at 1302 cm⁻¹ correspond to the N-H and C-N stretching vibrations of secondary amines, respectively. This indicates that PANI exists in the conductive emeraldine salt form due to its bipolaron structure. The peaks at 1558 cm⁻¹ and 1488 cm⁻¹ can be assigned to C = C stretching vibrations of quinoid and benzenoid rings. The peaks at 1244 cm⁻¹ and 1145 cm⁻¹ are attributed to C–H bending vibrations of benzenoid and quinonoid rings, respectively, while the peak at 815 cm⁻¹ corresponds to out-of-plane C-H bending in benzenoid rings. As reported in reference, MoS₂ exhibits no infrared absorption mode [23]. When compared with pure PANI, the infrared spectrum of PA 10 Mo 2 shows distinct changes: the wavenumbers of benzene and quinoid rings increase, a phenomenon resulting from the coupling between Au's surface plasmon and PANI's molecular vibration modes, as well as electronic interactions from MoS₂-PANI composite formation altering electron cloud distribution and chemical bond force constants. Conversely, the wavenumbers for secondary amine C-N and benzenoid out-of-plane C-H vibrations decrease, likely due to weak chemical or coordination bond formation between Au and secondary amine groups, combined with MoS₂'s layered structure restricting relevant vibrational degrees of freedom [24]. Furthermore, the incorporation of Au/MoS₂ disrupts hydrogen bonds between PANI chains, reduces crystallinity, and forms a confined interface, significantly increasing the exposure of active sites and the adsorption capacity. This synergistic effect between the electronic and structural properties greatly enhances the ammonia sensor's performance. The enhanced quinone structure and regulated electron density strengthen charge transfer between PANI and NH₃. The high conductivity of Au and the two-dimensional interface of MoS₂ accelerate electron transfer, enhancing the sensitivity and response speed. Meanwhile, the oxidation stability of the composite extends the sensor's lifespan, providing a theoretical basis for the design of efficient and stable ammonia gas detection devices. The XPS survey spectra of PANI, PA 10 , and PA 10 Mo 2 are shown in Fig. 3 (c), consistent with EDS results. The presence of Cl in PA 10 and PA 10 Mo 2 is due to the addition of HCl and AuCl 3 . To explore the impacts of MoS₂ and Au on PANI, the XPS spectra of the core-level N 1s orbital were analyzed (Fig. 3 (d)). In PANI's N1s spectrum, the three peaks at 398.91 eV, 399.74 eV, and 401.08 eV correspond to quinone imine (= N-), aniline (-NH-), and protonated amine (N⁺) respectively [25]. The N 1s spectra of PA 10 and PA 10 Mo 2 are presented in Fig. 3 (e) and Fig. 3 (f). The characteristic peaks of (= N-), (-NH-), and (N⁺) in PA 10 shift to about 398.30 eV, 399.44 eV, 400.62 eV, respectively, while in PA 10 Mo 2 they shift to 399.2 eV, 399.55 eV, 400.43 eV. By calculating the percentage values, the protonation degree can be compared. As shown in Table 1 , the proportion of N⁺ in PANI is 12.82%, in PA 10 is 23.33%, and in PA 10 Mo 2 is 45.87%, which is roughly three times that of PANI. This indicates that the addition of MoS₂ and Au enhances PANI's protonation degree and improves its gas-sensing performance. The doublet peaks of Au 4f in PA 10 are at 87.82 eV and 84.15 eV (Fig. S5(b)), and in PA 10 Mo 2 at 88.03 eV and 84.36 eV (Fig. 3 (g)), corresponding to Au 4f 7/2 and Au 4f 5/2 , respectively. In Fig. 3 (h) and (i), the fitting peaks of the Mo 3d spectrum at 227.08 eV, 230.01 eV, and 232.98 eV, correspond to S 2s, Mo⁴⁺ 3d 5/2 , and Mo⁴⁺ 3d 3/2 in MoS₂, respectively. The shifts of the Mo 3d and the N 1s orbital imply the potential existence of a coordination bond between Mo and N, and Au increases the bond energy of MoS₂. The two fitting peaks of the S 2p spectrum at 162.64 eV and 163.85 eV, corresponding to S²⁻ 2p 3/2 and S²⁻ 2p 1/2 in the S 2p orbital, respectively. Table 1 XPS atomic ratios of PANI, PA 10 and PA 10 Mo 2 . Samples Chemical groups =N- -NH- N + PANI 51.28% 35.90% 12.82% PA 10 9.35% 71.94% 18.71% PA 10 Mo 2 9.17% 44.95% 45.87% 3.2 Gas-sensing properties of PA 10 Mo 2 sensor As shown in Fig. S3(b), when exposed to the reducing NH₃, the resistance of the sensors increases, which confirms that the pure PANI, PA 10 , and PA 10 Mo 2 are p-type semiconductors. The base resistances are 3.16 kΩ, 4.79 kΩ, and 11.9 kΩ respectively, consistent with XRD analysis. In Fig. 4 (a), at an ammonia concentration of 1 ppm, the response of PA 10 Mo 2 is 92%, with response/recovery times of 69 s/89 s, compared to pure PANI's 95 s/156 s. PA 10 Mo 2 not only has a significantly higher response rate and shorter response/recovery times due to Au's catalytic acceleration, but its response value (15%) is also nearly six times higher. Figure 4 (b) compares the response values of PANI, PA 10 , and PA 10 Mo 2 at NH₃ concentrations of 1 ~ 50 ppm showing t PA 10 Mo 2 's response value is notably higher. Figure 4 (c) indicates that PA 10 Mo 2 responds at 14.5% to 5 ppb ammonia. Figure 4 (d) reveals a theoretical detection limit of 0.45 ppb for PA 10 Mo 2 , enabling trace NH₃ detection. The addition of Au and MoS₂ enhances both the response speed and value, attributed to the catalytic effect of Au nanoparticles and the multi-layer structure of MoS₂, providing more reaction sites for the interaction between polyaniline and the gas [26]. As depicted in Fig. 4 (e) and 4(f), within the NH₃ concentration ranges of 0.005 ~ 0.1 ppm and 0.1 ~ 50 ppm, the response shows a non-linear relationship as the NH₃ concentration gradually increases. This non-linear response behavior is due to the gradient saturation of the adsorption sites on the two-dimensional surface of MoS₂ and the synergistic modulation effect of the conductive channels of PANI in different concentration intervals. This unique dual-interval response endows the sensor with the advantages of trace identification (< 0.1 ppm) and a wide detection limit (0.005 ~ 50 ppm) in environmental monitoring. To evaluate the practical application capability of the sensor, we tested how the response value of PA 10 Mo 2 changes with temperature and humidity under 1 ppm NH 3 . As the temperature rose from 15°C to 55°C, the sensor's resistance increased slightly (Fig. 5 (a)), likely due to changes in the material's microstructure caused by thermal expansion, which increased the length or resistance of the charge transport path. However, the sensor's response decreased slightly with the temperature increase. This might be because higher temperatures accelerate the molecular diffusion rate of NH 3 , enabling rapid adsorption and desorption processes. This shortens the residence time of NH 3 on the film surface and reduces the saturated adsorption capacity of the sensor. Figure 5 (b) demonstrates the resistance and response value variations of the PA 10 Mo 2 sensor towards 1 ppm ammonia (NH₃) under different humidity conditions at room temperature. When the relative humidity (RH) increased from 25–40%, the PA 10 Mo 2 sensor exhibited a slight decrease in resistance accompanied by enhanced response values, which can be attributed to the "protonic effect" of the polyaniline (PANI) film. Under these conditions, environmental water molecules adsorb onto the sensing material surface, where both the adsorbed H₂O molecules and their ionized hydroxyl species (OH⁻) induce redoping of the PANI matrix. This redoping process effectively improves the electrical conductivity of PANI, thereby positively contributing to the enhancement of sensor response characteristics. Furthermore, continuous elevation of humidity may trigger the following chemical interactions: $$\:N{H}_{3}\:+\:{H}_{2}O\:\to\:\:N{H}_{4}^{+}\:+\:O{H}^{-}$$ Therefore, when exposed to NH 3 , both the sensor's resistance and response will increase. When the humidity further increased from 55–85%, the response stabilized at around 90%, and the resistance also became stable, indicating that MoS₂ and Au improved the moisture resistance of PANI. In conclusion, the response of the PA 10 Mo 2 shows slight variations within a humidity range of 25%~85%, demonstrating good moisture resistance. In complex atmospheric environments, sensor selectivity is of great significance. To assess PA 10 Mo 2 's selectivity, we tested several interfering gases, including H₂S (hydrogen sulfide), CO (carbon monoxide), CH₃OH (methanol), C₂H₅OH (ethanol), HCHO (formaldehyde), and CH₄ (methane). To ensure result consistency, all tests were performed at 25°C and 25% RH. The sensor's response to 1 ppm NH 3 is 92.5%, while for other gases at 500 ppm, the responses are all below 2% (Fig. 5 (c)). This demonstrates the excellent selectivity of PA 10 Mo 2 for NH₃. PA 10 Mo 2 's repeatability has been verified by continuous exposure to 1 ppm NH₃. The resistance of PA 10 Mo 2 remained stable after five measurement cycles (Fig. 5 (d)), indicating good repeatability. The PA 10 Mo 2 's long-term stability over a 30-day period was investigated through periodic measurements of its sensing performance. In Fig. 6 , the response of PA 10 Mo 2 exhibits slight variations, with each response value tightly clustered around 92.5%. This observation highlights the sensor's excellent long-term stability and its suitability for practical applications. In addition, various ammonia gas sensors in recent years are summarized in Table S1 [15, 28 ~ 33]. Evidently, the gas-sensing performance of the PA 10 Mo 2 sensor prepared in this work is excellent. 3.3. Sensing mechanism of PA 10 Mo 2 sensor The sensing mechanism of PANI towards NH₃ is based on the protonation/deprotonation effect. When doped with a protonic acid, H⁺ in the acid combines with the N atom on the imine group of PANI, causing protonation and the formation of polarons and bipolarons on the main chain. These charge carriers delocalize onto the PANI molecular chain, giving PANI high electrical conductivity. Upon exposure to NH₃, NH₃ molecules form coordination bonds with the protons in acidified PANI to produce NH 4 + . This leads to PANI's deprotonation, converting it from the conductive Emeraldine salt to the non-conductive Emeraldine base. The reduction of polarons in the PANI main chain decreases the charge carrier concentration, thus increasing the resistance. This process is reversible. When NH₃ is removed, NH 4 + decompose into NH₃ and H + , reprotonating PANI and restoring its conductivity. When exposed to air again, NH₄⁺ detaches from the PANI surface and decomposes into NH₃ and H⁺, increasing the charge carrier concentration and reducing the resistance. The reaction progress is llustrated in Fig. 7 (a) and (b). The PA 10 Mo 2 demonstrated superior gas-sensing performance compared to PANI and PA 10 . This performance enhancement stems from three pivotal aspects: (1) The p-n heterojunction effect at the PANI and MoS₂ interface substantially amplifies electrical response; (2) Incorporated gold nanoparticles not only provide additional catalytically active sites but also optimize reaction kinetics; (3) The distinctive 0D/1D/2D hybrid architecture effectively facilitates gas molecule adsorption and charge transfer processes. When the prototypical p-type conductive polymer polyaniline (bandgap 2.8 eV) interfaces with n-type molybdenum disulfide (bandgap 1.2 ~ 1.9 eV), Fermi level disparity induces charge carrier redistribution at the interfacial region [34]. This manifests as electron accumulation on the PANI side and hole accumulation on the MoS₂ side. Such carrier separation generates a space charge region at the interface, accompanied by band bending, built-in electric field formation, and pronounced barrier effects, ultimately elevating the composite's baseline resistance (as corroborated by XRD analysis). The incorporation of Au nanoparticles delivers dual optimization: Their surface plasmon resonance activates ammonia molecules while increasing active site density (verified by XPS characterization), significantly enhancing target gas recognition. Furthermore, Au nanoparticles guide the formation of PANI-based composites with hierarchical porous structures, where this unique morphology promotes rapid gas diffusion and expands reactive interfaces. During ammonia detection, the sensing material amplifies signals through dual mechanisms: The hole-enriched interfacial region enhances gas adsorption capacity, while proton exchange between NH₃ and PANI induces electron injection and depletion layer expansion, thereby intensifying the barrier effect. Notably, the Au component imparts exceptional structural stability, ensuring reliable long-term sensor operation. This innovative design, leveraging interfacial electronic structure modulation and synergistic effects with Au nanoparticles, endows the composite with exceptional electrical sensitivity to ammonia, achieving concurrent improvements in both detection capability and response speed. Conclusions This study synthesized a MEMS-based 0D/1D/2D PA 10 Mo 2 nanocomposite via chemical oxidative polymerization for ultra-sensitive room-temperature ammonia sensing. PA 10 Mo 2 outperformed pure PANI and PA 10 , achieving a 92.5% response to 1 ppm NH₃, 69 s/89 s response/recovery times, and a 0.45 ppb detection limit. It showed high selectivity against H₂S, CO, and nonlinear responses across various NH₃ concentrations. Temperature increases slightly raised resistance and reduced response, while the sensor maintained stability at 25%~85% humidity, with MoS₂ and Au enhancing PANI's moisture resistance. The excellent performance of PA 10 Mo 2 resulted from synergistic effects: a p-n heterojunction between PANI and MoS₂ enhanced electrical signals, Au nanoparticles optimized reaction kinetics, the 0D/1D/2D hierarchical structure boosted gas adsorption and charge transfer, and Au ensured long-term stability. These results not only provide an innovative ammonia-sensing solution with broad application potential but also offer guidance for the design of MEMS-based hierarchical structures. Moreover, it has great potential in the early diagnosis and real-time monitoring of diseases related to ammonia concentration changes in the human body, which contributes to improving the levels of medical diagnosis and treatment. Declarations Funding This work is supported by the Medical Scientific Research Foundation of Zhejiang Province (2023KY279), the Ningbo Key Scientific and Technological Project (NBSTI 2023Z021), and the Zhu Xiu Shan Talent Project of Ningbo No.2 Hospital (2023HMJQ25). Author Contribution Wenfeng Shen : Writing – review & editing, Supervision, Project administration, Funding acquisition, Conceptualization. Ping Luo： Writing – original draft, Investigation. Dawu Lv: Methodology, Conceptualization. Jin Zhang: formal analysis and validation. Ruiqin Tan: Writing – review & editing, Supervision, Conceptualization. Weijie Song: Supervision, Resources. Acknowledgement This work is supported by the Medical Scientific Research Foundation of Zhejiang Province (2023KY279), NBSTI (2023Z021), and the Zhu Xiu Shan Talent Project of Ningbo No.2 Hospital (2023HMJQ25). Thanks for the measuring support from Ningbo Qiwei Sense Technology. Co., Ltd. References Lefferts MJ, Castell MR (2022) Ammonia breath analysis. Sens Diagn 1:955–967. https://doi.org/10.1039/d2sd00089j Wu H, Li D, Liu J, et al (2024) Portable and hand-held ammonia gas sensor enables noninvasive prediagnosis of helicobacter pylori Infection. ACS Sens 9:5384–5393. https://doi.org/10.1021/acssensors.4c01609 Pogorzelska J, Łapińska M, Kalinowska A, et al (2017) Helicobacter pylori infection among patients with liver cirrhosis. Eur J Gastroenterol Hepatol 29:1161–1165. https://doi.org/10.1097/MEG.0000000000000928 Rath RJ, Herrington JO, Adeel M, et al (2024) Ammonia detection: A pathway towards potential point-of-care diagnostics. 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J Hazard Mater 485:136723. https://doi.org/10.1016/j.jhazmat.2024.136723 Xu H, Jiang C, Ye W, et al (2023) MoO 2 -MoS 2 composite coated with polyaniline as an anode material for high-performance lithium ion batteries. Ionics 30:85–94. https://doi.org/10.1007/s11581-023-05282-7 Zhang X, Yang Y, Li Z, et al (2019) Polyaniline-intercalated molybdenum disulfide composites for supercapacitors with high rate capability. J Phys Chem Solids 130:84-92. https://doi.org/10.1016/j.jpcs.2019.02.004 Zeng F-W, Liu X-X, Diamond D, Lau KT (2010) Humidity sensors based on polyaniline nanofibres. Sens Actuators B Chem 143:530–534. https://doi.org/10.1016/j.snb.2009.09.050 Li S, Diao Y, Yang Z, et al (2018) Enhanced room temperature gas sensor based on Au-loaded mesoporous In 2 O 3 nanospheres@polyaniline core-shell nanohybrid assembled on flexible PET substrate for NH 3 detection. Sens Actuators B Chem 276:526–533. https://doi.org/10.1016/j.snb.2018.08.120 Chen G, Yuan Y, Lang M, et al (2022) Core-shell Au@SiO 2 nanocrystals doped PANI for highly sensitive, reproducible and flexible ammonia sensor at room temperature. Appl Surf Sci 598:153821. https://doi.org/10.1016/j.apsusc.2022.153821 Akhtar K, Zubair N, Zeb N, et al (2025) Morphology controlled fabrication of zinc phosphate hierarchical microspheres for room temperature ammonia gas sensor. Sens Actuators Rep 9:100288. https://doi.org/10.1016/j.snr.2025.100288 Feng Z, Wen J, Meng F, et al (2024) In situ-polymerized PANI/WS 2 nanocomposites for highly sensitive flexible ammonia gas sensors and respiration monitoring devices. ACS Appl Nano Mater 7:3385–3393. https://doi.org/10.1021/acsanm.3c05965 Liu A (2021) The gas sensor utilizing polyaniline/MoS 2 nanosheets/SnO 2 nanotubes for the room temperature detection of ammonia. Sens Actuators B Chem 332:129444. https://doi.org/10.1016/j.jpcs.2019.02.004 Tian X, Cui X, Xiao Y, et al (2023) Pt/MoS 2 /polyaniline nanocomposite as a highly effective room temperature flexible gas sensor for ammonia detection. ACS Appl Mater Interfaces 15:9604–9617. https://doi.org/10.1021/acsami.2c20299 Additional Declarations No competing interests reported. Supplementary Files SupportingInformation250520.docx floatimage1.jpeg Graphical abstract Cite Share Download PDF Status: Published Journal Publication published 06 Aug, 2025 Read the published version in Microchimica Acta → Version 1 posted Reviewers agreed at journal 17 Jun, 2025 Reviewers agreed at journal 16 Jun, 2025 Reviewers agreed at journal 16 Jun, 2025 Reviewers agreed at journal 16 Jun, 2025 Reviewers invited by journal 16 Jun, 2025 Editor assigned by journal 21 May, 2025 Submission checks completed at journal 21 May, 2025 First submitted to journal 20 May, 2025 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-6704267","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":472468240,"identity":"4b8f7194-f829-4dcf-980f-ac2108811187","order_by":0,"name":"Ping Luo","email":"","orcid":"","institution":"Jiangxi University of Science and Technology","correspondingAuthor":false,"prefix":"","firstName":"Ping","middleName":"","lastName":"Luo","suffix":""},{"id":472468241,"identity":"1aca9c62-c35f-4321-b5f4-9ed02c22df4e","order_by":1,"name":"Wenfeng Shen","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAyUlEQVRIiWNgGAWjYDAC5gNsQNKGgY14LWwJIMVpQC3MpGk5DLKPSB0Gx9ifPfi443wen9j5gw8YauwY+Gc3ENLCY24488ztYjbpZGYDhmPJDBJ3DuDXYna/h02at+12Ypt0MpsEA9sBBgOJBAJagA6T/tt2DqSF/QfDP6K0MJhJM7YdANvCAGQQ1mJ/jMdMsrctGaTFWCKxL5lH4gYBLZJt7M8kfrbZJc6fnfjww4dvdnL8MwhoQQVAxTykqB8Fo2AUjIJRgAMAAOWWPDAuA3ZFAAAAAElFTkSuQmCC","orcid":"","institution":"Chinese Academy of Sciences","correspondingAuthor":true,"prefix":"","firstName":"Wenfeng","middleName":"","lastName":"Shen","suffix":""},{"id":472468242,"identity":"f443f2ac-9176-480e-868b-ef1d9616c043","order_by":2,"name":"Jin Zhang","email":"","orcid":"","institution":"Ningbo No.2 Hospital","correspondingAuthor":false,"prefix":"","firstName":"Jin","middleName":"","lastName":"Zhang","suffix":""},{"id":472468243,"identity":"e84f6498-7c90-4f32-9145-8eba9dfa7f88","order_by":3,"name":"Dawu Lv","email":"","orcid":"","institution":"Chinese Academy of Sciences","correspondingAuthor":false,"prefix":"","firstName":"Dawu","middleName":"","lastName":"Lv","suffix":""},{"id":472468244,"identity":"cae29e20-3e96-4098-9a5e-bd08785a4d75","order_by":4,"name":"Ruiqin Tan","email":"","orcid":"","institution":"Ningbo University","correspondingAuthor":false,"prefix":"","firstName":"Ruiqin","middleName":"","lastName":"Tan","suffix":""},{"id":472468245,"identity":"d903ce9b-d2f5-463d-933a-83aa32fee856","order_by":5,"name":"Weijie Song","email":"","orcid":"","institution":"Chinese Academy of Sciences","correspondingAuthor":false,"prefix":"","firstName":"Weijie","middleName":"","lastName":"Song","suffix":""}],"badges":[],"createdAt":"2025-05-20 06:23:14","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-6704267/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-6704267/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1007/s00604-025-07426-0","type":"published","date":"2025-08-06T15:57:18+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":84881525,"identity":"678a6d4d-a254-4d4b-bdba-e783d45e0625","added_by":"auto","created_at":"2025-06-18 10:58:07","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":313968,"visible":true,"origin":"","legend":"\u003cp\u003eSchematic illustration for the fabrication and gas testing of the PA\u003csub\u003e10\u003c/sub\u003eMo\u003csub\u003e2\u003c/sub\u003e sensor.\u003c/p\u003e","description":"","filename":"floatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-6704267/v1/4952259817a9d3f0d9d96391.png"},{"id":84883142,"identity":"0acf8757-7e60-4801-bf97-9406775c09f6","added_by":"auto","created_at":"2025-06-18 11:14:07","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":1263217,"visible":true,"origin":"","legend":"\u003cp\u003eSEM scanning images of the PAMo\u003csub\u003e2\u003c/sub\u003e film: \u003cstrong\u003e(a)\u003c/strong\u003e The whole MEMS-based PA\u003csub\u003e10\u003c/sub\u003eMo\u003csub\u003e2\u003c/sub\u003e sensing thin film; \u003cstrong\u003e(b)\u003c/strong\u003e The network structure of PANI; \u003cstrong\u003e(c)\u003c/strong\u003e The fibrous rod-like structure of PANI; \u003cstrong\u003e(d)~(e)\u003c/strong\u003e MoS₂; \u003cstrong\u003e(f)\u003c/strong\u003e Au nanoparticles; \u003cstrong\u003e(g)\u003c/strong\u003e EDS elemental images of C, N, O, Au, S, and Mo in PA\u003csub\u003e10\u003c/sub\u003eMo\u003csub\u003e2\u003c/sub\u003e; \u003cstrong\u003e(h)\u003c/strong\u003e EDS elemental images of C, N, O, Au, S, and Mo in MoS₂.\u003c/p\u003e","description":"","filename":"floatimage3.png","url":"https://assets-eu.researchsquare.com/files/rs-6704267/v1/8b4e782c01b9cafeac7721bf.png"},{"id":84881984,"identity":"8c41cd27-24f8-449e-adf8-b2659c508452","added_by":"auto","created_at":"2025-06-18 11:06:07","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":438895,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003e(a)\u003c/strong\u003e XRD diffraction pattern of PANI, PA\u003csub\u003e10\u003c/sub\u003e and PA\u003csub\u003e10\u003c/sub\u003eMo\u003csub\u003e2\u003c/sub\u003e; (b) FT-IR spectrum of PANI, PA\u003csub\u003e10\u003c/sub\u003e and PA\u003csub\u003e10\u003c/sub\u003eMo\u003csub\u003e2\u003c/sub\u003e; \u003cstrong\u003e(c-i)\u003c/strong\u003e XPS spectra of PANI, PA\u003csub\u003e10\u003c/sub\u003e and PA\u003csub\u003e10\u003c/sub\u003eMo\u003csub\u003e2\u003c/sub\u003e: \u003cstrong\u003e(c)\u003c/strong\u003e Full spectra; \u003cstrong\u003e(d)\u003c/strong\u003e N1s of PANI\u003cstrong\u003e; (e)\u003c/strong\u003e N1s of PA\u003csub\u003e10\u003c/sub\u003e; \u003cstrong\u003e(f)\u003c/strong\u003e N1s of PA\u003csub\u003e10\u003c/sub\u003eMo\u003csub\u003e2\u003c/sub\u003e. \u003cstrong\u003e(g)\u003c/strong\u003e Au 4f of PA\u003csub\u003e10\u003c/sub\u003eMo\u003csub\u003e2 \u003c/sub\u003e; \u003cstrong\u003e(h)~(i)\u003c/strong\u003e MoS\u003csub\u003e2\u003c/sub\u003e of PA\u003csub\u003e10\u003c/sub\u003eMo\u003csub\u003e2.\u003c/sub\u003e\u003c/p\u003e","description":"","filename":"floatimage4.png","url":"https://assets-eu.researchsquare.com/files/rs-6704267/v1/6b546d008589257cf15e697a.png"},{"id":84881526,"identity":"02fcb803-2fee-4cc9-b037-17132d5004b7","added_by":"auto","created_at":"2025-06-18 10:58:07","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":386570,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003e(a)\u003c/strong\u003e Responses of PA\u003csub\u003e10\u003c/sub\u003eMo\u003csub\u003e2\u003c/sub\u003e, PA\u003csub\u003e10\u003c/sub\u003e, and PANI at 1 ppm NH₃; \u003cstrong\u003e(b)\u003c/strong\u003e Responses of PA\u003csub\u003e10\u003c/sub\u003eMo\u003csub\u003e2\u003c/sub\u003e, PA\u003csub\u003e10\u003c/sub\u003e, and PANI at 1~50 ppm NH₃; \u003cstrong\u003e(c)\u003c/strong\u003e Responses of PA\u003csub\u003e10\u003c/sub\u003eMo\u003csub\u003e2\u003c/sub\u003e at 5~100 ppb; \u003cstrong\u003e(d)\u003c/strong\u003e The theoretical Limit of Detection of PA\u003csub\u003e10\u003c/sub\u003eMo\u003csub\u003e2\u003c/sub\u003e; \u003cstrong\u003e(e)~(f)\u003c/strong\u003e Fitting curves of the response versus the NH₃ concentration.\u003c/p\u003e","description":"","filename":"floatimage5.png","url":"https://assets-eu.researchsquare.com/files/rs-6704267/v1/30609492ed15fb84839c1641.png"},{"id":84881533,"identity":"2a47ffa0-6897-449e-a214-750fa45d2f80","added_by":"auto","created_at":"2025-06-18 10:58:07","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":476538,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003e(a)\u003c/strong\u003e Variations of the resistance and response of PA\u003csub\u003e10\u003c/sub\u003eMo\u003csub\u003e2\u003c/sub\u003e with temperature; \u003cstrong\u003e(b)\u003c/strong\u003e Variations of the resistance and response of PA\u003csub\u003e10\u003c/sub\u003eMo\u003csub\u003e2\u003c/sub\u003e with relative humidity; \u003cstrong\u003e(c)\u003c/strong\u003e Selectivity of PA\u003csub\u003e10\u003c/sub\u003eMo\u003csub\u003e2\u003c/sub\u003e; \u003cstrong\u003e(d)\u003c/strong\u003e Repeatability of the resistance value and response of PA\u003csub\u003e10\u003c/sub\u003eMo\u003csub\u003e2\u003c/sub\u003e.\u003c/p\u003e","description":"","filename":"floatimage6.png","url":"https://assets-eu.researchsquare.com/files/rs-6704267/v1/caf85186fa859849851f6a0d.png"},{"id":84881986,"identity":"2d98e993-187e-41ff-83b3-d0b643167c58","added_by":"auto","created_at":"2025-06-18 11:06:08","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":114950,"visible":true,"origin":"","legend":"\u003cp\u003eLong-term stability of PA\u003csub\u003e10\u003c/sub\u003eMo\u003csub\u003e2\u003c/sub\u003e\u003c/p\u003e","description":"","filename":"floatimage7.png","url":"https://assets-eu.researchsquare.com/files/rs-6704267/v1/7b27fa25bd2d0a2f4668f9b3.png"},{"id":84881989,"identity":"58156346-699b-462f-9497-524c0c3ca7a8","added_by":"auto","created_at":"2025-06-18 11:06:08","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":502183,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003e(a)\u003c/strong\u003e~\u003cstrong\u003e(b)\u003c/strong\u003e Sensing mechanism diagram of PA\u003csub\u003e10\u003c/sub\u003eMo\u003csub\u003e2\u003c/sub\u003e; \u003cstrong\u003e(c)\u003c/strong\u003e~\u003cstrong\u003e(d)\u003c/strong\u003e A p-n heterojunction at MoS₂ and PANI.\u003c/p\u003e","description":"","filename":"floatimage8.png","url":"https://assets-eu.researchsquare.com/files/rs-6704267/v1/bab1669f28839f424b56539e.png"},{"id":88814225,"identity":"fcb8d775-b948-45ab-84d7-08b6482a2671","added_by":"auto","created_at":"2025-08-11 16:08:43","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":4279331,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6704267/v1/5242aeab-b727-4391-8055-5211f6b55ed6.pdf"},{"id":84881988,"identity":"7ad9186c-d6fe-484c-aad4-51b9e9bfa6d4","added_by":"auto","created_at":"2025-06-18 11:06:08","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":4247393,"visible":true,"origin":"","legend":"","description":"","filename":"SupportingInformation250520.docx","url":"https://assets-eu.researchsquare.com/files/rs-6704267/v1/38868507200a680cacbc87ff.docx"},{"id":84881530,"identity":"131fe46a-24de-46e5-80b9-3435aa22ec21","added_by":"auto","created_at":"2025-06-18 10:58:07","extension":"jpeg","order_by":2,"title":"","display":"","copyAsset":false,"role":"supplement","size":488957,"visible":true,"origin":"","legend":"\u003cp\u003eGraphical abstract\u003c/p\u003e","description":"","filename":"floatimage1.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-6704267/v1/ef260ceba7203e74f39db49a.jpeg"}],"financialInterests":"No competing interests reported.","formattedTitle":"Ultra-Sensitive Room-Temperature Ammonia Detection Enabled by MEMS-Based 0D/1D/2D PA10Mo2 Nanocomposites","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eAmmonia (NH₃) is an important biomarker, with abnormal concentrations in human breath (\u0026gt;2 ppm), being closely associated with diseases such as liver and kidney dysfunction and Helicobacter pylori infection [1\u0026ndash;3]. This makes it a significant target for non-invasive diagnosis [4]. Traditional ammonia detection techniques, such as blood sampling and biopsy, are often painful and time-consuming for assessing liver and kidney function. Gas chromatography, on the other hand, relies on laboratory equipment and cannot meet the demands of point-of-care diagnostics for portability, low cost, and rapid response [5].\u003c/p\u003e \u003cp\u003eChemiresistive gas sensors have garnered extensive research attention owing to their low cost and flexibility, including wearable sensors and breath analyzers based on polyaniline [7], metal oxides [8, 9], and two-dimensional materials [11]. Although traditional metal oxide semiconductor (MOS) sensors can achieve high responses at elevated temperatures (usually 200\u0026thinsp;~\u0026thinsp;400\u0026deg;C), they suffer from significant drawbacks including high power consumption, which is incompatible with the low-power requirements of portable devices [12], and poor selectivity due to their broad-spectrum response, making them highly susceptible to interference from water vapor, ethanol, and other substances in complex gas environments [13]. These limitations have prompted researchers to explore new room-temperature sensing materials actively.\u003c/p\u003e \u003cp\u003eIn recent years, room-temperature ammonia sensing materials with low power consumption and high selectivity have become a research focus. Polyaniline (PANI), featuring a unique proton-doping mechanism, tunable conductivity, and room-temperature operation, has garnered significant attention. PANI's sensing performance hinges on redox state changes: upon exposure to NH₃, deprotonation of its protonated imine groups (=\u0026thinsp;NH⁺=) by NH₃ molecules reduces conductivity [15]. However, Pure PANI-based sensors face limitations, including high detection limits (ppm-level), slow response and recovery times, and humidity sensitivity. To address these, recent strategies involve material composites [16]. Introducing 2D transition metal dichalcogenides (e.g., MoS₂) to form heterostructures enhances active site density and charge transport [18, 19]. While noble metal nanoparticles (e.g., Au) reduce reaction energy barriers through catalysis and increase the active reaction sites. The PANI matrix enables room-temperature operation and synergizes with other components, providing a novel solution that balances sensitivity, selectivity, and stability.\u003c/p\u003e \u003cp\u003eBased on these findings, this study proposes, for the first time, a ternary hierarchical structure of PA\u003csub\u003e10\u003c/sub\u003eMo\u003csub\u003e2\u003c/sub\u003e integrated on a MEMS chip. The two-dimensional characteristics of MoS\u003csub\u003e2\u003c/sub\u003e increase the effective number of gas-material interaction sites and form a p-n heterojunction with PANI to enhance charge carrier mobility. At the same time, the catalysis from Au nanoparticles improves the kinetic processes of NH₃ adsorption and desorption. Meanwhile, the advantages of PANI for room-temperature operation are maintained. Experimental results demonstrate that the sensor exhibits high sensitivity and rapid recovery characteristics at room temperature, with a response value nearly eight times higher than that of pure PANI. This work not only provides a batch-integrable sensing solution for wearable electronics and Internet of Things nodes but also offers theoretical insights into the design paradigm of multi-dimensional nanocomposites.\u003c/p\u003e"},{"header":"2. Experimental section","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003e2.1 Materials\u003c/h2\u003e \u003cp\u003eMolybdenum disulfide (MoS₂, 99.9%, particle size 12 ~ 16 µm), ammonium persulfate (APS), hydrochloric acid (HCl, 36 ~ 38%), ammonium hydroxide (NH₄OH, 25.0 ~ 28.0%), aniline (≥ 99.0%) Gold(III) chloride (AuCl₃, 98%), MEMS micro-hotplate(CWSG-W200), deionized water (DI).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003e2.2 Materials characterizations and sensing performance tests\u003c/h2\u003e \u003cp\u003eTo investigate the static micro-morphology of the fabricated thin films, observations were conducted using a high-resolution scanning cold field-emission electron microscope (Regulus 8230 SEM). The chemical element distribution within the films was determined through energy-dispersive X-ray spectroscopy (EDS). Crystal structure characterization was performed using a high-power rotating-target polycrystalline X-ray diffractometer (XRD, D8 DISCOVER, Germany). Molecular structure analysis was carried out via an intelligent Fourier transform infrared spectrometer (FT-IR, NICOLET 6700, USA). Elemental composition and chemical states were analyzed using X-ray photoelectron spectroscopy (XPS, AXIS SUPRA, UK). Notably, powder samples were exclusively used for XRD analysis, while all other characterizations were performed on MEMS sensor films.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003e2.3 Preparation method of PA\u003csub\u003e10\u003c/sub\u003eMo\u003csub\u003e2\u003c/sub\u003e gas-sensitive material\u003c/h2\u003e \u003cp\u003eThe precursor solution was prepared by first mixing aniline with 2 mL of 1 M hydrochloric acid (HCl), followed by sequential addition of molybdenum disulfide (MoS₂) at varying concentrations (0.003 M, 0.09 M, 0.15 M, 0.21 M, 0.3 M). The precursor solution was subjected to 2-hour ultrasonic treatment and subsequently quiescently aged for 1 hour at 0 ~ 2°C. Following this, 48.6 µL of 0.33 M auric chloride (AuCl₃) solution was dropwise added under continuous ultrasonication at 0°C for 10 minutes. A vertically suspended MEMS chip was immersed in the resultant solution and maintained at 0 ~ 2°C for 30 hours. During the reaction, the solution color transitioned from light brown to dark green, indicating polymerization of aniline monomers into polyaniline (PANI). After the reaction, the chip was retrieved, rinsed three times with deionized water, and dried at 60°C.\u003c/p\u003e \u003cp\u003eThe final products comprised gold/polyaniline/molybdenum disulfide (Au/PANI/MoS₂) composites with varying MoS₂ loadings, designated as PA\u003csub\u003e10\u003c/sub\u003eMo\u003csub\u003e1\u003c/sub\u003e, PA\u003csub\u003e10\u003c/sub\u003eMo\u003csub\u003e2\u003c/sub\u003e, PA\u003csub\u003e10\u003c/sub\u003eMo\u003csub\u003e3\u003c/sub\u003e, PA\u003csub\u003e10\u003c/sub\u003eMo\u003csub\u003e4\u003c/sub\u003e, and PA\u003csub\u003e10\u003c/sub\u003eMo\u003csub\u003e5\u003c/sub\u003e based on MoS₂ concentration. For comparative analysis and mechanism investigation, control samples of pure polyaniline (PANI) and gold-aniline (Au-PANI) synthesized through analogous protocols were labeled as PANI and PA\u003csub\u003e10\u003c/sub\u003e, respectively.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003e2.4 Sensor fabrication and gas-sensing measurement\u003c/h2\u003e \u003cp\u003eUpon completion of thin-film fabrication, the sensor chip deposited with the thin film was encapsulated in a TO-5 standard semiconductor package through ultrasonic gold wire bonding technology (WE-2013, Shenzhen Weichen Technology Co., Ltd., in Fig. \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003e(a), followed by integration into a sensor testing module (CSMS6V4-CR10K, manufactured by CS-MicroSensor Co., Ltd., Ningbo, as displayed in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e) for subsequent gas sensing performance evaluation. The gas sensing characteristics of the sensor were systematically analyzed by a static gas sensor intelligent detection system (QX-G100M, Qiwei Sensor Technology Co., Ltd., Ningbo; depicted in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e), which facilitates real-time transmission of sensor resistance data to a computer via Bluetooth/USB interfaces at a sampling rate of 10 Hz.\u003c/p\u003e \u003cp\u003eEnvironmental conditions during testing were precisely regulated using a climate chamber (DHTHM-27-20-p-sd, Duoao Testing Equipment Co., Ltd., Shanghai; refer to Fig. \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003e(b)) for temperature and humidity control. Ammonia test gas was generated through the saturated vapor pressure method, while certified gas standards including nitrogen dioxide (NO₂), sulfur dioxide (SO₂), carbon dioxide (CO₂), ethanol (C₂H₅OH), acetone (C₃H₆O), formaldehyde (CH₂O), and methane (CH₄) were supplied by Hangzhou New Century Specialty Gases Co., Ltd.\u003c/p\u003e \u003cp\u003eThe gas-sensing performance metrics encompassed six critical parameters: response value, limit of detection (LOD), sensitivity, repeatability, selectivity, and long-term stability. The response value (S) is defined by the equation: \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:S\\:=\\:({R}_{g}\\:-\\:{R}_{a})/{R}_{a}\\:\\times\\:\\:100\\text{%}\\)\u003c/span\u003e\u003c/span\u003e, where Ra and Rg denote the electrical resistance values measured in ambient air and target gas atmosphere, respectively. The response time is defined as the duration required for the sensor to attain 90% of the total resistance variation upon exposure to the target gas, whereas the recovery time represents the period necessary for the resistance to return to 90% of its baseline value after re-exposure to air.\u003c/p\u003e \u003c/div\u003e"},{"header":"Results and discussion","content":"\u003ch2\u003e3.1 Characterization of materials\u003c/h2\u003e\u003cp\u003eBefore characterization, the ratio of MoS₂ to PANI in the composite was optimized according to the response values. As shown in Fig. S3(a), PA\u003csub\u003e10\u003c/sub\u003eMo\u003csub\u003e2\u003c/sub\u003e exhibited the highest response among all samples at both low (1 ppm) and high (10 ppm, 20 ppm) ammonia concentrations, indicating that MoS₂, Au, and PANI synergistically enhanced the ammonia response at this ratio. As the MoS₂ content increased, agglomeration intensified, reducing the gas-sensing advantages brought by MoS₂ itself. Therefore, unless otherwise specified, the composite material referred to hereafter is PA\u003csub\u003e10\u003c/sub\u003eMo\u003csub\u003e2\u003c/sub\u003e. As shown in Fig. S2 and Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e(a), the MEMS-based sensor features a 160 µm × 160 µm suspended platform. Fig. S4(a) and S4(b) present SEM images of PANI oxidized by APS and PA\u003csub\u003e10,\u003c/sub\u003e respectively. When Au³⁺ acts as the oxidizing agent, it gets reduced to form nanospheres that deposit on the Pt electrode (570 ~ 640 nm in diameter), while PANI forms nanorods covering the MEMS surface. As shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e(b) and (c), PANI exhibits a rod-like morphology with a width of 30 ~ 40 nm and a length ranging from 150 to 250 nm, densely and uniformly distributed on the MEMS chip. In Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e(a), the circled part represents MoS₂, which, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e(d), exhibits a 2D multi-layer flake structure. Au accumulates at MoS₂ edges, and its nanoparticles attract aniline monomers, thereby promoting the polymerization growth of polyaniline from the edges inward on the surface of MoS₂. As illustrated in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e(d) and (e), PANI is evenly distributed on and between MoS₂ layers. PANI grows vertically on MoS₂, providing more reaction sites with ammonia and shortening the gas transport path. Additionally, PANI connects MoS₂ and Au, forming a fishnet-like structure that increases the number of gas-material reaction channels. Besides aggregating at MoS₂ edges, Au is adsorbed onto interdigitated electrodes (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e(f)). The high affinity among Au nanoparticles promotes the aggregation of PANI near the Pt electrode, leading to uniform distribution of PANI across the entire MEMS chip [20]. The Au particle size, around 520 ~ 570 nm, is smaller than that of PA\u003csub\u003e10\u003c/sub\u003e. This is because MoS₂ promotes Au reduction and growth [21], enhancing its catalytic activity. Additionally, the EDS results show that Au is predominantly deposited on the Pt electrode, while Mo, S, C, N, and O are uniformly distributed across the chip (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e(g)). The existence of C, O, and N on MoS₂ in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e(f) indicates the presence of PANI on MoS₂. These findings confirm the successful in-situ oxidative polymerization of a MEMS-based 0D/1D/2D ternary multi-level PA\u003csub\u003e10\u003c/sub\u003eMo\u003csub\u003e2\u003c/sub\u003e thin film co-modified by Au and MoS₂ on the MEMS chip.\u003c/p\u003e\u003cp\u003eThe XRD analysis elucidated the crystallographic characteristics of PANI, PA\u003csub\u003e10\u003c/sub\u003e and PA\u003csub\u003e10\u003c/sub\u003eMo\u003csub\u003e2\u003c/sub\u003e. As illustrated in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e(a), PANI exhibited a broad, low-intensity diffraction signal within the 2θ range of 15 ~ 30°, attributed to the (200) crystallographic plane of its emeraldine salt (ES) form, confirming its semi-crystalline nature. Notably, anomalous signals detected in this region originated from NH₄Cl crystals formed by the reaction between the oxidizing agent (NH₄)₂S₂O₈ and the acidic medium (Fig. S5(a)). For the PA\u003csub\u003e10\u003c/sub\u003e, distinct diffraction peaks observed at 38.2°, 44.4°, 64.6°, and 77.5° correspond to the (111), (200), (220), and (311) planes of Au, respectively, with peak positions aligning precisely with the JCPDS reference database (Card No. A26-1080-1). The XRD patterns of PA\u003csub\u003e10\u003c/sub\u003eMo\u003csub\u003e2\u003c/sub\u003e retained the characteristic Au diffraction signatures while revealing additional peaks at 14.4°, 32.7° and 39.5°, which were indexed to the (002), (100), and (103) planes of hexagonal-phase MoS₂.All observed MoS₂ peaks exhibited minimal deviation from standard reference values (JCPDS 37-1492-33). Intriguingly, the absence of PANI-specific diffraction peaks in both PA\u003csub\u003e10\u003c/sub\u003e and PA\u003csub\u003e10\u003c/sub\u003eMo\u003csub\u003e2\u003c/sub\u003e suggests structural reorganization during synthesis. This phenomenon likely stems from the dissociation of hydrogen-bonding networks within PANI chains, driven by the redox interaction between AuCl₃ and PANI. Specifically, Cl⁻ ions bind to protons on the polymer backbone, forming HCl and inducing oxidative restructuring of benzene rings. These molecular-level alterations provide a plausible explanation for the significantly elevated initial electrical resistance observed in PA\u003csub\u003e10\u003c/sub\u003eMo\u003csub\u003e2\u003c/sub\u003e relative to pristine PANI and PA\u003csub\u003e10\u003c/sub\u003e [22].\u003c/p\u003e\u003cp\u003eFT-IR spectrum in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e(b) revealed the chemical structures of pure PANI, PA\u003csub\u003e10\u003c/sub\u003e, and PA\u003csub\u003e10\u003c/sub\u003eMo\u003csub\u003e2\u003c/sub\u003e. The broad band at 3446 cm⁻¹ and the peak at 1302 cm⁻¹ correspond to the N-H and C-N stretching vibrations of secondary amines, respectively. This indicates that PANI exists in the conductive emeraldine salt form due to its bipolaron structure. The peaks at 1558 cm⁻¹ and 1488 cm⁻¹ can be assigned to C = C stretching vibrations of quinoid and benzenoid rings. The peaks at 1244 cm⁻¹ and 1145 cm⁻¹ are attributed to C–H bending vibrations of benzenoid and quinonoid rings, respectively, while the peak at 815 cm⁻¹ corresponds to out-of-plane C-H bending in benzenoid rings. As reported in reference, MoS₂ exhibits no infrared absorption mode [23]. When compared with pure PANI, the infrared spectrum of PA\u003csub\u003e10\u003c/sub\u003eMo\u003csub\u003e2\u003c/sub\u003e shows distinct changes: the wavenumbers of benzene and quinoid rings increase, a phenomenon resulting from the coupling between Au's surface plasmon and PANI's molecular vibration modes, as well as electronic interactions from MoS₂-PANI composite formation altering electron cloud distribution and chemical bond force constants. Conversely, the wavenumbers for secondary amine C-N and benzenoid out-of-plane C-H vibrations decrease, likely due to weak chemical or coordination bond formation between Au and secondary amine groups, combined with MoS₂'s layered structure restricting relevant vibrational degrees of freedom [24]. Furthermore, the incorporation of Au/MoS₂ disrupts hydrogen bonds between PANI chains, reduces crystallinity, and forms a confined interface, significantly increasing the exposure of active sites and the adsorption capacity. This synergistic effect between the electronic and structural properties greatly enhances the ammonia sensor's performance. The enhanced quinone structure and regulated electron density strengthen charge transfer between PANI and NH₃. The high conductivity of Au and the two-dimensional interface of MoS₂ accelerate electron transfer, enhancing the sensitivity and response speed. Meanwhile, the oxidation stability of the composite extends the sensor's lifespan, providing a theoretical basis for the design of efficient and stable ammonia gas detection devices.\u003c/p\u003e\u003cp\u003eThe XPS survey spectra of PANI, PA\u003csub\u003e10\u003c/sub\u003e, and PA\u003csub\u003e10\u003c/sub\u003eMo\u003csub\u003e2\u003c/sub\u003e are shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e(c), consistent with EDS results. The presence of Cl in PA\u003csub\u003e10\u003c/sub\u003e and PA\u003csub\u003e10\u003c/sub\u003eMo\u003csub\u003e2\u003c/sub\u003e is due to the addition of HCl and AuCl\u003csub\u003e3\u003c/sub\u003e. To explore the impacts of MoS₂ and Au on PANI, the XPS spectra of the core-level N 1s orbital were analyzed (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e(d)). In PANI's N1s spectrum, the three peaks at 398.91 eV, 399.74 eV, and 401.08 eV correspond to quinone imine (= N-), aniline (-NH-), and protonated amine (N⁺) respectively [25]. The N 1s spectra of PA\u003csub\u003e10\u003c/sub\u003e and PA\u003csub\u003e10\u003c/sub\u003eMo\u003csub\u003e2\u003c/sub\u003e are presented in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e(e) and Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e(f). The characteristic peaks of (= N-), (-NH-), and (N⁺) in PA\u003csub\u003e10\u003c/sub\u003e shift to about 398.30 eV, 399.44 eV, 400.62 eV, respectively, while in PA\u003csub\u003e10\u003c/sub\u003eMo\u003csub\u003e2\u003c/sub\u003e they shift to 399.2 eV, 399.55 eV, 400.43 eV. By calculating the percentage values, the protonation degree can be compared. As shown in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e, the proportion of N⁺ in PANI is 12.82%, in PA\u003csub\u003e10\u003c/sub\u003e is 23.33%, and in PA\u003csub\u003e10\u003c/sub\u003eMo\u003csub\u003e2\u003c/sub\u003e is 45.87%, which is roughly three times that of PANI. This indicates that the addition of MoS₂ and Au enhances PANI's protonation degree and improves its gas-sensing performance. The doublet peaks of Au 4f in PA\u003csub\u003e10\u003c/sub\u003e are at 87.82 eV and 84.15 eV (Fig. S5(b)), and in PA\u003csub\u003e10\u003c/sub\u003eMo\u003csub\u003e2\u003c/sub\u003e at 88.03 eV and 84.36 eV (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e(g)), corresponding to Au 4f\u003csub\u003e7/2\u003c/sub\u003e and Au 4f\u003csub\u003e5/2\u003c/sub\u003e, respectively. In Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e(h) and (i), the fitting peaks of the Mo 3d spectrum at 227.08 eV, 230.01 eV, and 232.98 eV, correspond to S 2s, Mo⁴⁺ 3d\u003csub\u003e5/2\u003c/sub\u003e, and Mo⁴⁺ 3d\u003csub\u003e3/2\u003c/sub\u003e in MoS₂, respectively. The shifts of the Mo 3d and the N 1s orbital imply the potential existence of a coordination bond between Mo and N, and Au increases the bond energy of MoS₂. The two fitting peaks of the S 2p spectrum at 162.64 eV and 163.85 eV, corresponding to S²⁻ 2p\u003csub\u003e3/2\u003c/sub\u003e and S²⁻ 2p\u003csub\u003e1/2\u003c/sub\u003e in the S 2p orbital, respectively.\u003c/p\u003e\u003cdiv class=\"gridtable\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eXPS atomic ratios of PANI, PA\u003csub\u003e10\u003c/sub\u003e and PA\u003csub\u003e10\u003c/sub\u003eMo\u003csub\u003e2\u003c/sub\u003e.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e\u003ccolgroup cols=\"7\"\u003e\u003c/colgroup\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSamples\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colspan=\"5\" nameend=\"c7\" namest=\"c3\"\u003e \u003cp\u003eChemical groups\u003c/p\u003e \u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e=N-\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-NH-\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eN\u003csup\u003e+\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePANI\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e51.28%\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e35.90%\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e12.82%\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePA\u003csub\u003e10\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e9.35%\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e71.94%\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e18.71%\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePA\u003csub\u003e10\u003c/sub\u003eMo\u003csub\u003e2\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e9.17%\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e44.95%\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e45.87%\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/table\u003e\u003c/div\u003e\u003ch2\u003e3.2 Gas-sensing properties of PA\u003csub\u003e10\u003c/sub\u003eMo\u003csub\u003e2\u003c/sub\u003e sensor\u003c/h2\u003e\u003cp\u003eAs shown in Fig. S3(b), when exposed to the reducing NH₃, the resistance of the sensors increases, which confirms that the pure PANI, PA\u003csub\u003e10\u003c/sub\u003e, and PA\u003csub\u003e10\u003c/sub\u003eMo\u003csub\u003e2\u003c/sub\u003e are p-type semiconductors. The base resistances are 3.16 kΩ, 4.79 kΩ, and 11.9 kΩ respectively, consistent with XRD analysis. In Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e(a), at an ammonia concentration of 1 ppm, the response of PA\u003csub\u003e10\u003c/sub\u003eMo\u003csub\u003e2\u003c/sub\u003e is 92%, with response/recovery times of 69 s/89 s, compared to pure PANI's 95 s/156 s. PA\u003csub\u003e10\u003c/sub\u003eMo\u003csub\u003e2\u003c/sub\u003e not only has a significantly higher response rate and shorter response/recovery times due to Au's catalytic acceleration, but its response value (15%) is also nearly six times higher. Figure\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e(b) compares the response values of PANI, PA\u003csub\u003e10\u003c/sub\u003e, and PA\u003csub\u003e10\u003c/sub\u003eMo\u003csub\u003e2\u003c/sub\u003e at NH₃ concentrations of 1 ~ 50 ppm showing t PA\u003csub\u003e10\u003c/sub\u003eMo\u003csub\u003e2\u003c/sub\u003e's response value is notably higher. Figure\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e(c) indicates that PA\u003csub\u003e10\u003c/sub\u003eMo\u003csub\u003e2\u003c/sub\u003e responds at 14.5% to 5 ppb ammonia. Figure\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e(d) reveals a theoretical detection limit of 0.45 ppb for PA\u003csub\u003e10\u003c/sub\u003eMo\u003csub\u003e2\u003c/sub\u003e, enabling trace NH₃ detection. The addition of Au and MoS₂ enhances both the response speed and value, attributed to the catalytic effect of Au nanoparticles and the multi-layer structure of MoS₂, providing more reaction sites for the interaction between polyaniline and the gas [26]. As depicted in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e(e) and 4(f), within the NH₃ concentration ranges of 0.005 ~ 0.1 ppm and 0.1 ~ 50 ppm, the response shows a non-linear relationship as the NH₃ concentration gradually increases. This non-linear response behavior is due to the gradient saturation of the adsorption sites on the two-dimensional surface of MoS₂ and the synergistic modulation effect of the conductive channels of PANI in different concentration intervals. This unique dual-interval response endows the sensor with the advantages of trace identification (\u0026lt; 0.1 ppm) and a wide detection limit (0.005 ~ 50 ppm) in environmental monitoring.\u003c/p\u003e\u003cp\u003eTo evaluate the practical application capability of the sensor, we tested how the response value of PA\u003csub\u003e10\u003c/sub\u003eMo\u003csub\u003e2\u003c/sub\u003e changes with temperature and humidity under 1 ppm NH\u003csub\u003e3\u003c/sub\u003e. As the temperature rose from 15°C to 55°C, the sensor's resistance increased slightly (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e(a)), likely due to changes in the material's microstructure caused by thermal expansion, which increased the length or resistance of the charge transport path. However, the sensor's response decreased slightly with the temperature increase. This might be because higher temperatures accelerate the molecular diffusion rate of NH\u003csub\u003e3\u003c/sub\u003e, enabling rapid adsorption and desorption processes. This shortens the residence time of NH\u003csub\u003e3\u003c/sub\u003e on the film surface and reduces the saturated adsorption capacity of the sensor.\u003c/p\u003e\u003cp\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e(b) demonstrates the resistance and response value variations of the PA\u003csub\u003e10\u003c/sub\u003eMo\u003csub\u003e2\u003c/sub\u003e sensor towards 1 ppm ammonia (NH₃) under different humidity conditions at room temperature. When the relative humidity (RH) increased from 25–40%, the PA\u003csub\u003e10\u003c/sub\u003eMo\u003csub\u003e2\u003c/sub\u003e sensor exhibited a slight decrease in resistance accompanied by enhanced response values, which can be attributed to the \"protonic effect\" of the polyaniline (PANI) film. Under these conditions, environmental water molecules adsorb onto the sensing material surface, where both the adsorbed H₂O molecules and their ionized hydroxyl species (OH⁻) induce redoping of the PANI matrix. This redoping process effectively improves the electrical conductivity of PANI, thereby positively contributing to the enhancement of sensor response characteristics.\u003c/p\u003e\u003cp\u003eFurthermore, continuous elevation of humidity may trigger the following chemical interactions:\u003c/p\u003e\u003cdiv id=\"Equa\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equa\" name=\"EquationSource\"\u003e\n$$\\:N{H}_{3}\\:+\\:{H}_{2}O\\:\\to\\:\\:N{H}_{4}^{+}\\:+\\:O{H}^{-}$$\u003c/div\u003e\u003c/div\u003e\u003cp\u003eTherefore, when exposed to NH\u003csub\u003e3\u003c/sub\u003e, both the sensor's resistance and response will increase. When the humidity further increased from 55–85%, the response stabilized at around 90%, and the resistance also became stable, indicating that MoS₂ and Au improved the moisture resistance of PANI. In conclusion, the response of the PA\u003csub\u003e10\u003c/sub\u003eMo\u003csub\u003e2\u003c/sub\u003e shows slight variations within a humidity range of 25%~85%, demonstrating good moisture resistance.\u003c/p\u003e\u003cp\u003eIn complex atmospheric environments, sensor selectivity is of great significance. To assess PA\u003csub\u003e10\u003c/sub\u003eMo\u003csub\u003e2\u003c/sub\u003e's selectivity, we tested several interfering gases, including H₂S (hydrogen sulfide), CO (carbon monoxide), CH₃OH (methanol), C₂H₅OH (ethanol), HCHO (formaldehyde), and CH₄ (methane). To ensure result consistency, all tests were performed at 25°C and 25% RH. The sensor's response to 1 ppm NH\u003csub\u003e3\u003c/sub\u003e is 92.5%, while for other gases at 500 ppm, the responses are all below 2% (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e(c)). This demonstrates the excellent selectivity of PA\u003csub\u003e10\u003c/sub\u003eMo\u003csub\u003e2\u003c/sub\u003e for NH₃. PA\u003csub\u003e10\u003c/sub\u003eMo\u003csub\u003e2\u003c/sub\u003e's repeatability has been verified by continuous exposure to 1 ppm NH₃. The resistance of PA\u003csub\u003e10\u003c/sub\u003eMo\u003csub\u003e2\u003c/sub\u003e remained stable after five measurement cycles (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e(d)), indicating good repeatability. The PA\u003csub\u003e10\u003c/sub\u003eMo\u003csub\u003e2\u003c/sub\u003e's long-term stability over a 30-day period was investigated through periodic measurements of its sensing performance. In Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e, the response of PA\u003csub\u003e10\u003c/sub\u003eMo\u003csub\u003e2\u003c/sub\u003e exhibits slight variations, with each response value tightly clustered around 92.5%. This observation highlights the sensor's excellent long-term stability and its suitability for practical applications. In addition, various ammonia gas sensors in recent years are summarized in Table \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003e [15, 28 ~ 33]. Evidently, the gas-sensing performance of the PA\u003csub\u003e10\u003c/sub\u003eMo\u003csub\u003e2\u003c/sub\u003e sensor prepared in this work is excellent.\u003c/p\u003e\u003ch2\u003e3.3. Sensing mechanism of PA\u003csub\u003e10\u003c/sub\u003eMo\u003csub\u003e2\u003c/sub\u003e sensor\u003c/h2\u003e\u003cp\u003eThe sensing mechanism of PANI towards NH₃ is based on the protonation/deprotonation effect. When doped with a protonic acid, H⁺ in the acid combines with the N atom on the imine group of PANI, causing protonation and the formation of polarons and bipolarons on the main chain. These charge carriers delocalize onto the PANI molecular chain, giving PANI high electrical conductivity. Upon exposure to NH₃, NH₃ molecules form coordination bonds with the protons in acidified PANI to produce NH\u003csub\u003e4\u003c/sub\u003e\u003csup\u003e+\u003c/sup\u003e. This leads to PANI's deprotonation, converting it from the conductive Emeraldine salt to the non-conductive Emeraldine base. The reduction of polarons in the PANI main chain decreases the charge carrier concentration, thus increasing the resistance. This process is reversible. When NH₃ is removed, NH\u003csub\u003e4\u003c/sub\u003e\u003csup\u003e+\u003c/sup\u003e decompose into NH₃ and H\u003csup\u003e+\u003c/sup\u003e, reprotonating PANI and restoring its conductivity. When exposed to air again, NH₄⁺ detaches from the PANI surface and decomposes into NH₃ and H⁺, increasing the charge carrier concentration and reducing the resistance. The reaction progress is llustrated in Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e(a) and (b).\u003c/p\u003e\u003cp\u003eThe PA\u003csub\u003e10\u003c/sub\u003eMo\u003csub\u003e2\u003c/sub\u003e demonstrated superior gas-sensing performance compared to PANI and PA\u003csub\u003e10\u003c/sub\u003e. This performance enhancement stems from three pivotal aspects: (1) The p-n heterojunction effect at the PANI and MoS₂ interface substantially amplifies electrical response; (2) Incorporated gold nanoparticles not only provide additional catalytically active sites but also optimize reaction kinetics; (3) The distinctive 0D/1D/2D hybrid architecture effectively facilitates gas molecule adsorption and charge transfer processes.\u003c/p\u003e\u003cp\u003eWhen the prototypical p-type conductive polymer polyaniline (bandgap 2.8 eV) interfaces with n-type molybdenum disulfide (bandgap 1.2 ~ 1.9 eV), Fermi level disparity induces charge carrier redistribution at the interfacial region [34]. This manifests as electron accumulation on the PANI side and hole accumulation on the MoS₂ side. Such carrier separation generates a space charge region at the interface, accompanied by band bending, built-in electric field formation, and pronounced barrier effects, ultimately elevating the composite's baseline resistance (as corroborated by XRD analysis).\u003c/p\u003e\u003cp\u003eThe incorporation of Au nanoparticles delivers dual optimization: Their surface plasmon resonance activates ammonia molecules while increasing active site density (verified by XPS characterization), significantly enhancing target gas recognition. Furthermore, Au nanoparticles guide the formation of PANI-based composites with hierarchical porous structures, where this unique morphology promotes rapid gas diffusion and expands reactive interfaces.\u003c/p\u003e\u003cp\u003eDuring ammonia detection, the sensing material amplifies signals through dual mechanisms: The hole-enriched interfacial region enhances gas adsorption capacity, while proton exchange between NH₃ and PANI induces electron injection and depletion layer expansion, thereby intensifying the barrier effect. Notably, the Au component imparts exceptional structural stability, ensuring reliable long-term sensor operation.\u003c/p\u003e\u003cp\u003eThis innovative design, leveraging interfacial electronic structure modulation and synergistic effects with Au nanoparticles, endows the composite with exceptional electrical sensitivity to ammonia, achieving concurrent improvements in both detection capability and response speed.\u003c/p\u003e"},{"header":"Conclusions","content":"\u003cp\u003eThis study synthesized a MEMS-based 0D/1D/2D PA\u003csub\u003e10\u003c/sub\u003eMo\u003csub\u003e2\u003c/sub\u003e nanocomposite via chemical oxidative polymerization for ultra-sensitive room-temperature ammonia sensing. PA\u003csub\u003e10\u003c/sub\u003eMo\u003csub\u003e2\u003c/sub\u003e outperformed pure PANI and PA\u003csub\u003e10\u003c/sub\u003e, achieving a 92.5% response to 1 ppm NH₃, 69 s/89 s response/recovery times, and a 0.45 ppb detection limit. It showed high selectivity against H₂S, CO, and nonlinear responses across various NH₃ concentrations. Temperature increases slightly raised resistance and reduced response, while the sensor maintained stability at 25%~85% humidity, with MoS₂ and Au enhancing PANI's moisture resistance. The excellent performance of PA\u003csub\u003e10\u003c/sub\u003eMo\u003csub\u003e2\u003c/sub\u003e resulted from synergistic effects: a p-n heterojunction between PANI and MoS₂ enhanced electrical signals, Au nanoparticles optimized reaction kinetics, the 0D/1D/2D hierarchical structure boosted gas adsorption and charge transfer, and Au ensured long-term stability. These results not only provide an innovative ammonia-sensing solution with broad application potential but also offer guidance for the design of MEMS-based hierarchical structures. Moreover, it has great potential in the early diagnosis and real-time monitoring of diseases related to ammonia concentration changes in the human body, which contributes to improving the levels of medical diagnosis and treatment.\u003c/p\u003e"},{"header":"Declarations","content":"\u003ch2\u003eFunding\u003c/h2\u003e \u003cp\u003eThis work is supported by the Medical Scientific Research Foundation of Zhejiang Province (2023KY279), the Ningbo Key Scientific and Technological Project (NBSTI 2023Z021), and the Zhu Xiu Shan Talent Project of Ningbo No.2 Hospital (2023HMJQ25).\u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eWenfeng Shen : Writing \u0026ndash; review \u0026amp; editing, Supervision, Project administration, Funding acquisition, Conceptualization. Ping Luo： Writing \u0026ndash; original draft, Investigation. Dawu Lv: Methodology, Conceptualization. Jin Zhang: formal analysis and validation. Ruiqin Tan: Writing \u0026ndash; review \u0026amp; editing, Supervision, Conceptualization. Weijie Song: Supervision, Resources.\u003c/p\u003e\u003ch2\u003eAcknowledgement\u003c/h2\u003e\u003cp\u003eThis work is supported by the Medical Scientific Research Foundation of Zhejiang Province (2023KY279), NBSTI (2023Z021), and the Zhu Xiu Shan Talent Project of Ningbo No.2 Hospital (2023HMJQ25). Thanks for the measuring support from Ningbo Qiwei Sense Technology. Co., Ltd.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eLefferts MJ, Castell MR (2022) Ammonia breath analysis. Sens Diagn 1:955\u0026ndash;967. https://doi.org/10.1039/d2sd00089j\u003c/li\u003e\n\u003cli\u003eWu H, Li D, Liu J, et al (2024) Portable and hand-held ammonia gas sensor enables noninvasive prediagnosis of helicobacter pylori Infection. 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ACS Appl Mater Interfaces 15:9604\u0026ndash;9617. https://doi.org/10.1021/acsami.2c20299\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"microchimica-acta","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"miac","sideBox":"Learn more about [Microchimica Acta](https://link.springer.com/journal/604)","snPcode":"604","submissionUrl":"https://submission.springernature.com/new-submission/604/3","title":"Microchimica Acta","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Ammonia sensor, Polyaniline, MEMS-based sensor, Room-temperature, MoS2","lastPublishedDoi":"10.21203/rs.3.rs-6704267/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6704267/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eIn this study, a 0D/1D/2D Au/Polyaniline/MoS₂ (PA\u003csub\u003e10\u003c/sub\u003eMo\u003csub\u003e2\u003c/sub\u003e) hierarchical nanocomposite based on microelectromechanical systems (MEMS) was successfully synthesized via in situ chemical oxidative polymerization. The 0D, 1D, and 2D materials in the composite form a three-dimensional transport network; the surfaces of MoS₂, PANI, and Au promote gas diffusion through unsaturated bonds, polar groups, and high surface energy, respectively. The sensor fabricated from this composite exhibits response and recovery times of 69 seconds and 89 seconds, respectively, at room temperature for 1 ppm of ammonia, whereas those of pure PANI are 95 seconds and 156 seconds, respectively. Additionally, gold nanoparticles regulate the growth and distribution of PANI and MoS₂, increasing the active sites in the film from 12.82% to 45.87%. Moreover, the built-in electric field of the p-n heterojunction formed between PANI and MoS₂ drives the directional movement of carriers, optimizing carrier transport. When the ammonia concentration is 1 ppm, the sensor can achieve a response of 92.5%, and its theoretical minimum detection limit is 0.45 ppb. This work presents an innovative and efficient solution for ammonia sensing at room temperature, demonstrating significant potential in the fields of wearable electronic devices and human health monitoring.\u003c/p\u003e","manuscriptTitle":"Ultra-Sensitive Room-Temperature Ammonia Detection Enabled by MEMS-Based 0D/1D/2D PA10Mo2 Nanocomposites","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-06-18 10:58:03","doi":"10.21203/rs.3.rs-6704267/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"reviewerAgreed","content":"184666084703721522341474454921239708587","date":"2025-06-17T09:37:07+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"307422132994773968450237242208888011556","date":"2025-06-17T00:25:21+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"104717535132599115759539228050902203253","date":"2025-06-16T14:09:51+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"185419389273137292986507304854809428084","date":"2025-06-16T11:30:47+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-06-16T09:02:14+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-05-22T00:42:54+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-05-22T00:41:09+00:00","index":"","fulltext":""},{"type":"submitted","content":"Microchimica Acta","date":"2025-05-20T06:12:24+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"microchimica-acta","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"miac","sideBox":"Learn more about [Microchimica Acta](https://link.springer.com/journal/604)","snPcode":"604","submissionUrl":"https://submission.springernature.com/new-submission/604/3","title":"Microchimica Acta","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"9ca04338-56c8-4fb3-9e8a-099d64976cb7","owner":[],"postedDate":"June 18th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2025-08-11T16:04:42+00:00","versionOfRecord":{"articleIdentity":"rs-6704267","link":"https://doi.org/10.1007/s00604-025-07426-0","journal":{"identity":"microchimica-acta","isVorOnly":false,"title":"Microchimica Acta"},"publishedOn":"2025-08-06 15:57:18","publishedOnDateReadable":"August 6th, 2025"},"versionCreatedAt":"2025-06-18 10:58:03","video":"","vorDoi":"10.1007/s00604-025-07426-0","vorDoiUrl":"https://doi.org/10.1007/s00604-025-07426-0","workflowStages":[]},"version":"v1","identity":"rs-6704267","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6704267","identity":"rs-6704267","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}