Thermocouple-Integrated Resonant Microcantilever for On-chip Thermogravimetric (TG) and Differential Thermal Analysis (DTA) Dual Characterization Applications

Thermocouple-Integrated Resonant Microcantilever for On-chip Thermogravimetric (TG) and Differential Thermal Analysis (DTA) Dual Characterization Applications | 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 Article Thermocouple-Integrated Resonant Microcantilever for On-chip Thermogravimetric (TG) and Differential Thermal Analysis (DTA) Dual Characterization Applications Xinxin Li, Yuhang Yang, Hao Jia, Zechun Li, Zhi Cao, Pengcheng Xu This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4662720/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 26 Mar, 2025 Read the published version in Microsystems & Nanoengineering → Version 1 posted 11 You are reading this latest preprint version Abstract This work presents an integrated microsensor that combines the dual characterization capabilities of thermogravimetric analysis (TGA) and differential thermal analysis (DTA). We integrated two pairs of thermocouples, heating resistors, and resonant drive/detection resistors into one microcantilever to achieve programmable temperature control, temperature change, and mass detection in a single chip. Our chip can achieve heating and cooling rates above 600°C/min, which is significantly faster than commercial instruments with satisfactory measurement accuracy. The integrated polysilicon thermocouples bring high power responsivity of 6V/W, making them suitable for highly sensitive DTA measurements on a chip. Moreover, the cantilever offers picogram (10 -12 g) level mass resolution, reducing sample consumption from milligrams to nanogram levels. Additionally, the on-chip sample heating allows for easy observation of sample morphological evolution during heating under an optical microscope. We validated the dual functionality by conducting TGA measurements on a standard sample of calcium oxalate monohydrate (CaC 2 O 4 ∙H 2 O) and DTA measurements on high-purity indium (In) and tin (Sn). The results indicate consistent measurements with the true values of the standard sample and high measurement efficiency. Our integrated cantilever chip is anticipated to have broad applications in high-performance and efficient TGA and DTA characterization. Thermogravimetric analysis Differential thermal analysis resonant cantilever thermocouple scientific instrument Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Introduction Thermal analysis technologies evaluate temperature-dependent properties of substances under controlled conditions and are widely used in chemical engineering, food safety, and drug analysis. 1 – 6 . Among the developed thermal analysis techniques, thermogravimetric analysis (TGA) and differential thermal analysis (DTA) stand out as two widely used characterization methods 5 , 6 . TGA is a classic characterization technique for measuring the mass change of materials during programmed heating in a particular atmosphere, and is frequently used to investigate the thermal stability of materials as well as the thermal properties of materials such as evaporation, decomposition, dehydration, and oxidation during the heating process. 7 , 8 . DTA primarily measures the temperature shifts of material in programmed temperatures, enabling the investigation of the endothermic or exothermic properties of materials during phase transitions or chemical reactions 9 , 10 . Therefore, the combined characterization of TGA and DTA techniques is conducive to establishing comprehensive, multidimensional thermal properties of materials 11 , which is of great significance for the rapidly advanced new functional materials and related research fields 12 . Although TGA and DTA instruments have been commercialized for decades, their inherent shortcomings have become increasingly evident in the rapid advancement of new functional materials and related research fields 13 – 15 . Due to the bulk size of commercial DTA instruments, a large heat capacity is introduced, resulting in a power response typically in the mV/W level 16 , 17 . Therefore, to ensure sufficient DTA signal amplitude, the sample consumption of commercial DTA instruments should not be too small, typically on the milligram level 18 – 20 . Meanwhile, the thermal balances used in current commercial instruments normally have mass sensitivities on the sub-microgram scale 21 , so mg-level samples are also required for commercial TGA measurement. The available commercial DTA and TGA instruments usually employ a crucible to hold the sample, preventing direct contact between the temperature measuring element and the sample itself, which introduces an inaccuracy in the temperature measurement. However, at high heating rates, mg-scale samples are difficult to heat uniformly, and a wide temperature distribution occurs, causing the TGA and DTA signals of the samples to have a hysteresis relative to the true values, and this hysteresis becomes more significant as the heating rate increases 22 – 24 . Hence, commercial instruments typically limit the heating rate to less than 100–200°C/min to ensure measurement accuracy 15 , 16 , resulting in time-consuming traditional TGA/DTA measurement, negatively affecting the efficiency of new materials development. Furthermore, the high sample volume of current commercial instruments is not conducive to measuring expensive, small batches of materials such as new drugs. Using a closed bulk furnace by commercial instruments to heat the sample presents a challenge in integrating the microscope for in situ optical observation of sample appearance 13 , 25 . We note that based on MEMS (micro-electromechanical system) technology, many pairs of thermocouples have been integrated into chips, enabling on-chip DTA analysis capabilities 13 , 18 , 19 . However, such chips cannot accurately measure the sample mass, let alone perform on-chip TGA analysis. Our group initially used a micro-resonant cantilever integrated with on-chip heating and mass measurement functions, which enabled the on-chip TGA measurement of samples at the nanogram level 26 – 29 . However, the cantilever can only determine the overall temperature by measuring the change in the resistance of the heater and cannot accurately measure the sample temperature. To date, the available MEMS sensors can only measure TGA or have DTA capabilities, but they have not yet been able to perform both functions on a single chip. Herein, an integrated resonant microcantilever is proposed and developed to achieve dual thermal functions of TGA and DTA on a single MEMS chip. We integrated two pairs of polysilicon thermocouples into the resonant microcantilever, thus allowing further DTA measurement of samples while retaining the TGA function. The tiny structure of the microcantilever results in a significant reduction in the heat capacity of the chip, leading to a power responsivity at the V/W level, which is three orders of magnitude higher than that of commercial DTA instruments. Our chips achieve heating and cooling rates above 600°C/min, which is one to two orders of magnitude higher than conventional instruments, significantly improving the efficiency of TGA and DTA measurement. Reducing the volume of sample requirements allows for uniform heating during the rapid heating process. Furthermore, the sample is loaded directly onto the thermocouple integrated into the cantilever, ensuring highly accurate temperature detection. Thus, precise and efficient on-chip MEMS TGA and DTA characterization can be realized with our cantilever. Moreover, the integrated microcantilever has dimensions on the micron scale, and the integrated on-chip heater obviates the necessity for a heating oven, thus enabling the chip to be placed under a microscope for in situ optical observation of the morphological evolutions that occur in the sample during thermal analysis. We have employed the above thermocouple-integrated resonant microcantilever chip for TGA or DTA measurement of a diverse range of materials, including metals (indium and tin standards) and calcium oxalate monohydrate (CaC₂O₄·H₂O). Results Sensor Design and Fabrication Figure 1 a shows a schematic illustration of the integrated cantilever. The sample is placed directly onto the free end of the cantilever, which has an integrated heater for on-chip heating and cooling. Two polysilicon thermocouples are also integrated into the cantilever. The hot junction is in the sample area, while the cold junction is on the bulk silicon substrate, ensuring accurate temperature detection. To separate the high-temperature zone from the low-temperature zone, an adiabatic window is placed in the center of the cantilever to block heat transfer from the free end to the fixed end. The detection of mass changes in loaded samples is based on the resonance frequency shift of the cantilever. As shown in Fig. 1 b, we use integrated thermocouples that rely on the Seebeck effect to detect the temperature difference between hot and cold junctions 30 , 31 . According to the Seebeck effect, the output voltage of thermocouples can be expressed as 31 , 32 : \(\begin{array}{c}V=N\left({{\alpha }}_{B}-{{\alpha }}_{A}\right)\left({T}_{hot}-{T}_{env}\right)=N\left({{\alpha }}_{B}-{{\alpha }}_{A}\right)\left({T}_{heat}-{T}_{env}+\varDelta {T}_{loading}\right)\#\left(1\right)\end{array}\) where N is the number of thermocouple pairs, α A and α B are the Seebeck coefficient values of the two materials that form the thermocouples. T hot is the temperature of the hot junction, which is composed of the temperature generated by the heater ( T heat ) and the temperature difference caused by the loaded sample (Δ T loading ). T env is the temperature of the environment. Therefore, we can measure the T hot by recording the output voltage of thermocouples. To perform DTA measurement, two integrated cantilever chips with identical characteristics should be applied simultaneously under the same conditions to reduce the common mode noise and disturbances. One chip acts as a reference sensor, and the other as a test sensor for the load sample. Hence, the differential output voltage between reference and sensing can be expressed as: $$\begin{array}{c}\varDelta V=N\left({{\alpha }}_{B}-{{\alpha }}_{A}\right)\left({\varDelta T}_{heat}+\varDelta {T}_{loading}\right)\#\left(2\right)\end{array}$$ The Δ T heat is the difference between temperatures generated by heaters, caused by differences between chips in the specifications such as the heating resistance, the heat capacity, and the thermal conductance. It may be caused by some inevitable unevenness in the deposition rate and etching rate in the fabrication process. Therefore, it can be eliminated by measuring the same chips before loading the sample under the same conditions as the baseline for formal DTA measurement. This method allows us to determine the temperature difference produced by the loaded samples. As illustrated in Fig. 1 c, we utilize the frequency change of the cantilever to quantify the mass change based on the conservation of mechanical energy at the resonant cantilever. When a small mass change occurs at the free end, and the mass change is much smaller than the effective mass of the cantilever, the relationship between the mass change and the 1st mode frequency shift can be expressed as 27 – 29 , 33 . $$\begin{array}{c}\varDelta m\approx \frac{k\varDelta f}{2{\pi }^{2}{{f}_{0}}^{3}}=2{m}_{eff}\frac{\varDelta f}{{f}_{0}}\#\left(3\right)\end{array}$$ where Δ m is the tiny mass change on the free end, k is the elastic coefficient of the cantilever, f 0 is the resonant frequency of the cantilever before mass loading, Δ f is the resonant frequency shift of the cantilever, and m eff is the effective mass. The Eq. (3) shows that a small change in mass is directly proportional to the frequency change. In our chips, we can measure the mass change in real time by recording the frequency shift of the resonant cantilever, as shown in Fig. 1 b. Figure 2 a shows the detailed structure of the integrated cantilever chips. The sample loading area is near the free end, where the surrounding bulk silicon is etched to reduce additional heat capacity. Molybdenum (Mo) is utilized to create microheaters for precise temperature control. The two hot junctions of the thermocouples are covered with semicircular molybdenum to ensure a uniform temperature across the sample region. For high temperature-sensitivity, we use n + and p + polysilicon to fabricate the thermocouple, which has a Seebeck coefficient significantly higher than the commonly used metals in IC fabrication 13 , 30 . In order to achieve both integrated resonance excitation and frequency readout functions, a silicon resistor is designed near the fixed end of the cantilever for electrothermal driving. Additionally, a Wheatstone bridge composed of silicon piezoresistors is fabricated near the fixed end to facilitate resonant frequency readout 27 , 33 . Due to the limitations of silicon resistors, which may not function properly at temperatures exceeding 125°C 29 , 34 , a thermal isolation window has been designed to separate the heater and piezoresistors. This design blocks direct thermal conduction within the cantilever while improving thermal resistance from the sample area to the surrounding environment. As a result, the design of the thermal isolation window helps to increase the power responsivity of the system. We then perform finite element simulation to model the temperature distribution of the integrated cantilever using COMSOL Multiphysics analysis software. The software modeled the thermoelectrically generated heat using the electric current interface. The element also accounts for convective heat transfer in the air atmosphere and a fixed convective heat dissipation coefficient is set to reduce simulation time without compromising accuracy. The thermal conductivity of single-crystal silicon is adjusted for temperature based on the literature 35 to improve accuracy at high temperatures. Figure 2 b illustrates the simulation results for the overall temperature distribution on the surface of the cantilever when the temperature at the center of the sample region reaches 500°C. Additionally, we conducted a simulation to analyze the impact of the thermal isolation window, which blocks heat transfer from the free end to the fixed end. Figure 2 c presents the effect of the thermal isolation window on the temperature distribution along the center axis of the cantilever. With the isolation window, the temperature around the Wheatstone bridge remains below 65°C as the temperature at the free end exceeds 500°C. In contrast, without the isolation window, the temperature around the Wheatstone bridge increases to 160°C, which could lead to p-n junction leakage. The simulation results demonstrate effective thermal isolation between the free and fixed ends, protecting the resonant excitation and readout silicon resistors at high operating temperatures. In Fig. 2 d, the temperature distribution of the sample loading region along the horizontal axis is shown at different heating voltages. The simulation results indicate a uniform temperature distribution in the center of the sample loading region, with a variation of within ± 1%. Our chips are produced on 4-inch (100) SOI wafers, enabling precise control over the cantilever layer thickness of 3 µm, a handle layer thickness of 500 µm, and a box layer thickness of 700 nm. The detailed fabrication process is shown in Fig. 3 : (a) The thermal SiO 2 of 350nm is fabricated through a heating oxidation furnace. After photolithography and RIE etch of SiO 2 , a pool is defined by KOH wet etching for the sample loading region. (b) The silicon resistors of resonant excitation and readout resistors (Wheatstone bridge) are defined by photolithography, ion-implantation, and diffusion. (c-d) After depositing 200nm of SiNx and 500nm of polysilicon films by LPCVD, the main part of polysilicon thermocouples is fabricated through ion implantation, diffusion, and RIE sequentially. A 300nm SiNx film is then deposited to protect the thermocouples. (e) After etching the connection window of the polysilicon thermocouple and silicon resistors, the Mo films are patterned using the lift-off process to create microheaters and connect the thermocouples. Subsequently, the Al films are patterned using the lift-off process to establish electrical connections for the silicon resistors. (f) Depositing a 200nm PECVD Si 3 N 4 layer provides protection against oxidation and electrical isolation. (g) A RIE process of dielectric layers is followed by DRIE of the device layer and RIE of the box layer to form the shape of the resonant cantilever. (h) The handle layer is removed from the back side using a DRIE process, thus releasing the cantilever. Characterization of the Integrated Cantilever Chips Figure 4 a depicts the morphological image of the manufactured resonant cantilevers. The cantilever measures 340 µm in length, 190 µm in width, and 3 µm in thickness. The sample loading area has a diameter of 60 µm, and the thermal isolation window measures 100 µm × 90 µm. The SEM image of the cantilever in Fig. 4 a clearly reveals the structure and morphology of the integrated thermocouple, heater, resonant excitation/readout resistor, and sample loading area. Figure 4 b illustrates the wafer-level fabrication of the cantilever chips on a 4-inch SOI wafer. Figure 4 c schematically depicts the test system for TGA and DTA measurements. The resonant excitation and readout resistors of the sensing chip are connected to a phase-locked-loop (PLL) circuit for tracking the resonant frequency. The output voltage from the thermocouples and integrated heaters of both chips is connected to a signal readout and heater drive circuit, which records and controls the temperature of the sample region. Both circuits are linked to a computer for data recording and further processing. The temperature dependence of the chip was first assessed by measuring the temperatures of the hot junction at various heating voltages using a non-contact infrared thermal imager with a spatial resolution of 20 µm. Simultaneously, the test system recorded the output voltage of the thermocouples. Figure 5 a shows the measured and simulated temperatures of the sample loading area as a function of the heating voltage, and the agreement is very good, indicating that our simulation is reliable. The sample region can be heated up to 530℃ under a heating voltage of 6.2V. Meanwhile, Fig. 5 b shows the corresponding relationship between the output voltage and heating power of the seven chips. The average power response of each chip is 6.1V/W, which is three orders of magnitude higher than that of traditional instruments (generally in the mV/W level) 16 , 17 , and the relative standard deviation is only 3%, indicating strong consistency between different chips. In Fig. 5 c, the output voltage of thermocouples is shown for different measured temperatures. The output voltage demonstrates a linear response to the temperature, with a high-temperature responsivity of 0.73mV/K. The root-mean-square ( rms ) voltage noise of the MEMS thermocouples can be expressed as follows: $$\begin{array}{c}{V}_{noise,rms}=\sqrt{4{k}_{B}TRB}\#\left(4\right)\end{array}$$ where k B is the Boltzmann’s constant, T is the room temperature, R is the thermocouples resistance (10kΩ), and B is the system bandwidth (400Hz) 19 , 20 . According to Eq. (3), we can have a rms voltage noise of 0.26µV for our chips. Therefore, we can calculate a noise equivalent temperature (NET) of 2.8mK, based on the 8×V noise, rms , and temperature responsivity 20 . We also measure the change in heating resistance with the working temperature, as illustrated in Fig. 5 d, indicating a TCR (temperature coefficient of resistance) of 0.0014/K. Then, the mass-sensing properties of the fabricated cantilevers are calibrated. A flowing DC-biased AC is applied to the excitation resistor, and the Wheatstone bridge is also connected to the PLL interface circuit. In this way, we can measure the real-time frequency shift. The resonant frequency of our cantilever is approximately 35 kHz, with a Q factor of 190. To calibrate the mass sensitivity of our cantilever, we measure the resonant frequency of the cantilever before and after placing a standard polystyrene (PS) sphere on the sample region, as illustrated in Fig. 6 a-b. The diameter of the standard PS sphere is 25 µm, and the density is 1.05 g/cm 3 . A resonant frequency change of 399 Hz is measured after loading the standard PS sphere, which leads to a mass responsivity of 0.090 Hz/pg for the cantilever. The noise floor of the frequency signal is approximately 0.5 Hz, leading to a mass resolution of 5.5 pg. Therefore, our chips can conduct thermogravimetric analysis with ng-level samples. When the sample region of the cantilever is heated from room temperature to 400℃, only a slight frequency shift of 50 Hz is measured, equivalent to a mass change of 0.56 ng. DTA Measurement Using Integrated Cantilever Chips Metal standards with a fixed melting point are commonly used to calibrate DTA measurements. In this work, we have selected indium (In) and tin (Sn) standards to validate our DTA measurement performance. As mentioned above, two chips are used simultaneously in DTA measurement. One chip contains a sample, while the other is left empty. The DTA measurements are carried out at various heating rates in an air atmosphere. Because our cantilevers are small, we place them under a microscope to observe the morphological changes of the samples in situ during the DTA measurements. We first measure the melting process of In and Sn at a heating rate of 10°C/s. The results are shown in Fig. 7 a-b. We can observe the sharp heat absorption peak caused by the melting process. The video in Supporting Material S1 and the insets in Fig. 7 a show the in situ optical images of the indium melting process. The indium undergoes a noticeable morphological change after reaching its melting point. Based on the heat absorption peak in the measured DTA curve, we can calculate the melting point of the metal using our chips 36 . The measured melting point of indium is 157.7°C, which is only 1.1°C higher than the standard value of 156.5°C in literature 36 , 37 . As for tin, the melting point is measured as 231.7℃, only 0.2℃ smaller than the standard valve (231.9℃) 37 . The results presented in Fig. 8 a-b confirm the temperature accuracy of our chips. We further test the indium melting and solidification process at different heating and cooling rates from 1°C /s to 200°C /s. The heat absorption and release during melting and solidification processes induce sharp peaks in the DTA curves, as shown in Fig. 7 c. As the rate of temperature rise and fall increases, the DTA signal becomes larger, thereby facilitating the measurement of small heat absorption or exothermic processes. We also calculate the melting point of indium at different heating rates, as shown in Fig. 7 d. The melting point at 200°C/s exhibits only a 5°C difference compared to the melting point at 1°C /s. The results demonstrate that the chip exhibits small thermal hysteresis even at rapid temperature changes. TGA Measurement Using Integrated Cantilever Chips To demonstrate the technical merit of our integrated cantilever in TGA measurement, inorganic crystals with known molecular structures are selected. CaC 2 O 4 ∙H 2 O is a standard substance for evaluating TGA measurement. The TGA measurement by our cantilevers is performed at a heating rate of 600°C/min in an air atmosphere. We also measure the same sample with a conventional TGA instrument at heating rates of 10℃/min and 200℃/min. The results are plotted together in Fig. 8 for comparison. Two stages of decomposition can be observed in the TGA curves measured from room temperature to 620°C. The first stage can be assigned to the loss of water of crystallization with a weight loss of 12.2%. The second stage shows a weight loss of 20.3%, which indicates CaC 2 O 4 decomposed into CaCO 3 . Both decomposition-induced weight losses are consistent with the theoretical values (12.32%, 19.16%) 34,38 . When the CaC 2 O 4 ∙H 2 O sample was analyzed using a conventional TGA instrument (NETZSCH TG 209 F1 Libra), the TGA curve obtained at a heating rate of 200°C/min showed a significant hysteresis compared to the test at a heating rate of 10°C/min. Fortunately, even when heating at a high rate of 600°C/min, the TGA results obtained with the cantilever closely match those obtained with a conventional TGA instrument using a heating rate of 10°C/min. The results suggest that the thermal hysteresis phenomenon of the cantilever is minimal in MEMS TGA analysis, and it dramatically improves the efficiency of the TGA analysis. Conclusion In summary, we have developed and fabricated an integrated resonant microcantilever for performing both thermogravimetric analysis (TGA) and differential thermal analysis (DTA) measurements. Each microcantilever chip includes a microheater, resonance excitation/readout resistors, and thermocouples to enable controlled heating, precise mass detection at the picogram level, and accurate temperature measurement. Our cantilevers show a power responsivity of 6.1V/W, temperature sensitivity of 0.73mV/°C, and temperature resolution of 2.8mK. Our cantilevers also have a mass sensitivity of 0.09 Hz/pg and a mass resolution of 5.5pg. We then performed TGA measurements on CaC 2 O 4 ∙H 2 O and DTA measurements on indium and tin metal standards. Our test results demonstrate that our chip can perform high-precision TGA and DTA analysis. Our chip has faster heating/cooling speeds and consumes fewer samples than conventional TGA and DTA instruments. Our integrated cantilever device is expected to enable efficient TGA and DTA testing in various essential application areas in physics, chemistry, metallurgy, pharmaceuticals, and nanotechnology. Declarations AUTHOR INFORMATION Corresponding Author *Corresponding author * Pengcheng Xu − State Key Lab of Transducer Technology, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050, China; University of Chinese Academy of Sciences, Beijing 100049, China; Email: [email protected] * Xinxin Li − State Key Lab of Transducer Technology, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050, China; University of Chinese Academy of Sciences, Beijing 100049, China; Email: [email protected] Funding Sources This research was funded by the National Key R&D Program of China (2021YFB3200800), National Natural Science Foundation of China (62227815, 61831021, 62271473, 62104241, U21A20500), and Innovation Team and Talents Cultivation Program of National Administration of Traditional Chinese Medicine (ZYYCXTD-D-202002, ZYYCXTD-D-202003). 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Additional Declarations (Not answered) Supplementary Files indiummelting.mp4 Supporting Material S1 Video of the indium melting during DTA measurement using our chips Cite Share Download PDF Status: Published Journal Publication published 26 Mar, 2025 Read the published version in Microsystems & Nanoengineering → Version 1 posted Editorial decision: revise 05 Aug, 2024 Review # 2 received at journal 30 Jul, 2024 Review # 3 received at journal 17 Jul, 2024 Review # 1 received at journal 14 Jul, 2024 Reviewer # 3 agreed at journal 11 Jul, 2024 Reviewer # 2 agreed at journal 07 Jul, 2024 Reviewer # 1 agreed at journal 07 Jul, 2024 Reviewers invited by journal 07 Jul, 2024 Submission checks completed at journal 01 Jul, 2024 Editor assigned by journal 30 Jun, 2024 First submitted to journal 30 Jun, 2024 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. 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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-4662720","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":323642173,"identity":"8b382408-2d16-4b73-b28a-652c7377a9bc","order_by":0,"name":"Xinxin Li","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAzElEQVRIie3RIQ7CMBSA4bc0aU1DLSQku0InEYyrjMwWNMnEOgMGPCep3qiYAT8J4QJLUDjaGRTd5hD9TWe+9rUD8Pn+MiTLFoBOzGc5kASyOhuCRxFEzYIHj8WbdaGXIp5jII9LA3EI5OY+bXaspN6o1AxGuRaQRpJuEydhpLAEWQKGoASmlDsJRoHUC5UbQu6G5P2kOyVQ2r6YHUz3E3uX6qRqipG9C6+jPRVuwptUt2+VrRg5PF9il4WMXN3kG+p2GPODfD6fz/ezD6BhOrO55I+nAAAAAElFTkSuQmCC","orcid":"","institution":"Shanghai Institute of Microsystem and Information Technology,CAS","correspondingAuthor":true,"prefix":"","firstName":"Xinxin","middleName":"","lastName":"Li","suffix":""},{"id":323642174,"identity":"c5d368b2-8e24-4c7b-b562-0df23dd51690","order_by":1,"name":"Yuhang Yang","email":"","orcid":"","institution":"Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, CHINA","correspondingAuthor":false,"prefix":"","firstName":"Yuhang","middleName":"","lastName":"Yang","suffix":""},{"id":323642175,"identity":"97223241-aa74-4b24-a598-2910486865cf","order_by":2,"name":"Hao Jia","email":"","orcid":"https://orcid.org/0000-0002-1429-6995","institution":"Shanghai Institute of Microsystem and Information Technology,CAS","correspondingAuthor":false,"prefix":"","firstName":"Hao","middleName":"","lastName":"Jia","suffix":""},{"id":323642176,"identity":"67bfb12a-6530-406a-b6fd-f87cb9d0280a","order_by":3,"name":"Zechun Li","email":"","orcid":"","institution":"Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, CHINA","correspondingAuthor":false,"prefix":"","firstName":"Zechun","middleName":"","lastName":"Li","suffix":""},{"id":323642177,"identity":"c3dd5089-ff36-48af-8b56-8347c260d11c","order_by":4,"name":"Zhi Cao","email":"","orcid":"","institution":"Shanghai Institute of Technology","correspondingAuthor":false,"prefix":"","firstName":"Zhi","middleName":"","lastName":"Cao","suffix":""},{"id":323642178,"identity":"be3ca8b3-6a25-44a0-abb8-d84654894fd5","order_by":5,"name":"Pengcheng Xu","email":"","orcid":"","institution":"Shanghai Institute of Microsystem and Information Technology,CAS","correspondingAuthor":false,"prefix":"","firstName":"Pengcheng","middleName":"","lastName":"Xu","suffix":""}],"badges":[],"createdAt":"2024-06-30 12:40:10","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4662720/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4662720/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1038/s41378-024-00828-9","type":"published","date":"2025-03-26T04:00:00+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":61530491,"identity":"8c80cd24-e76f-4f62-ab09-71f38f0781d6","added_by":"auto","created_at":"2024-07-31 22:36:46","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":357606,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eWorking principle of the integrated cantilever. a\u003c/strong\u003e Schematic illustration of the resonant microcantilever for TGA and DTA measurement, with a core component of the cantilever for mass measuring and the thermocouples for temperature sensing. \u003cstrong\u003eb\u003c/strong\u003e Based on the Seebeck effect, the output voltage of the thermocouple is proportional to the temperature difference, thus being able to record the temperature change caused by the endothermic (or exothermic) process. \u003cstrong\u003ec\u003c/strong\u003e Based on the proportional relationship between mass change (Δ\u003cem\u003em\u003c/em\u003e) and the measured resonant frequency shift (Δ\u003cem\u003ef\u003c/em\u003e) of the microcantilever, the real-time measured frequency signal can be transformed into a typical TGA curve.\u003c/p\u003e","description":"","filename":"figure1.png","url":"https://assets-eu.researchsquare.com/files/rs-4662720/v1/8a1fe31683cbcde564a563bd.png"},{"id":61530179,"identity":"1f80e707-3853-4346-9814-361c4ee61389","added_by":"auto","created_at":"2024-07-31 22:20:46","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":571619,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eStructure and finite element simulation results of the resonant cantilever. a\u003c/strong\u003e 3D model of the cantilever illustrating its thermocouple, sample loading area, and integrated heater. \u003cstrong\u003eb\u003c/strong\u003e The temperature distribution simulation results are obtained by considering key factors such as electrical heating, heat transfer and air convection. \u003cstrong\u003ec\u003c/strong\u003e Simulation results show the hindering role of the thermal isolation window on heat conduction.\u003cstrong\u003e d\u003c/strong\u003e Simulation results of the temperature of the hot junction show good uniformity (variation within ±1%).\u003c/p\u003e","description":"","filename":"figure2.png","url":"https://assets-eu.researchsquare.com/files/rs-4662720/v1/73770a9a8d8fd604b9fec27c.png"},{"id":61530326,"identity":"6e4f10d4-8e8c-45fd-9dd3-7f27dcb45434","added_by":"auto","created_at":"2024-07-31 22:28:46","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":45460,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eFabrication process of the integrated cantilever chips. a\u003c/strong\u003e KOH etching of sample loading region after thermal oxidation. \u003cstrong\u003eb\u003c/strong\u003eIon-implantation of resonant excitation and readout resistance. \u003cstrong\u003ec\u003c/strong\u003e LPCVD SiNx and polysilicon deposition. \u003cstrong\u003ed\u003c/strong\u003e Fabrication of thermocouples through ion-implantation, diffusion, and RIE, and then depositing LPCVD SiNx. \u003cstrong\u003ee\u003c/strong\u003e Patterning of Mo heater and Al electric connection. \u003cstrong\u003ef\u003c/strong\u003e PECVD film deposition for antioxidant protection. \u003cstrong\u003eg\u003c/strong\u003eDRIE for the device layer to pattern the shape of the cantilever. \u003cstrong\u003eh\u003c/strong\u003e DRIE is used to handle the layer and release the cantilever.\u003c/p\u003e","description":"","filename":"figure3.png","url":"https://assets-eu.researchsquare.com/files/rs-4662720/v1/9def935dfe54ee59d39c1cdb.png"},{"id":61530324,"identity":"40c625be-d55a-4a38-b808-57eac9233ac9","added_by":"auto","created_at":"2024-07-31 22:28:46","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":2531225,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eImage of the integrated cantilever and schematic diagram of the testing system. a\u003c/strong\u003e SEM image of the cantilever, showing the detail of the integrated component. \u003cstrong\u003eb\u003c/strong\u003e Microcantilevers fabricated on 4-inch SOI wafers.\u003cstrong\u003e c\u003c/strong\u003e Schematic diagram of the test system for TGA and DTA measurements.\u003c/p\u003e","description":"","filename":"figure4.png","url":"https://assets-eu.researchsquare.com/files/rs-4662720/v1/9e7ad5beecc7be509561c4ae.png"},{"id":61530182,"identity":"80715dbe-f3c1-463c-bc85-e2db013ec606","added_by":"auto","created_at":"2024-07-31 22:20:46","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":215140,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eTest results for the thermal properties of microcantilevers. a\u003c/strong\u003e The temperature at the hot junction is measured under different heating voltages, and the result is in agreement with the simulation. \u003cstrong\u003eb\u003c/strong\u003e The output voltage of the thermocouple at various heating powers indicates a high power response of 6.1V/W.\u003cstrong\u003e c\u003c/strong\u003e The hot junction output voltage vs. temperature shows a temperature response of 0.73mV/°C. \u003cstrong\u003ed\u003c/strong\u003e The relationship between the heating voltage and the heating resistance indicates that the TCR is 0.0014/°C.\u003c/p\u003e","description":"","filename":"figure5.png","url":"https://assets-eu.researchsquare.com/files/rs-4662720/v1/1e0a078539501e2f31c83ae2.png"},{"id":61530186,"identity":"4f05b68b-79b8-49ca-9a8c-c1bd8c375a16","added_by":"auto","created_at":"2024-07-31 22:20:47","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":660194,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eMass sensitivity of the microcantilever. a\u003c/strong\u003e Optical images of the cantilever before and after loading with a standard PS sphere. \u003cstrong\u003eb\u003c/strong\u003e Based on the frequency and amplitude of the cantilever before and after loading with a standard PS sphere, the mass sensitivity of the cantilever can be tested to be 0.09 Hz/pg.\u003cstrong\u003e c\u003c/strong\u003e The noise floor is approximately 0.5 Hz, resulting in a mass resolution of 5.5 pg. \u003cstrong\u003ed\u003c/strong\u003e Frequency variation with operating temperature. Within the tested temperature range, the maximum frequency shift is 50Hz.\u003c/p\u003e","description":"","filename":"figure6.png","url":"https://assets-eu.researchsquare.com/files/rs-4662720/v1/c59f3c8410f355ab4ccdfda4.png"},{"id":61530185,"identity":"991d2d7f-4d5d-4cf2-9db7-53f7f1b25428","added_by":"auto","created_at":"2024-07-31 22:20:46","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":266327,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eDifferential thermal analysis results of metal standards. \u003c/strong\u003eDTA curves of the In (\u003cstrong\u003ea\u003c/strong\u003e) and Sn (\u003cstrong\u003eb\u003c/strong\u003e) standards melting under a heating rate of 10°C/s. The measured melting points of In and Sn are consistent with the reported values. The \u003cem\u003ein situ\u003c/em\u003eoptical images in insets in \u003cstrong\u003ea\u003c/strong\u003e depict the process of indium melting. \u003cstrong\u003ec\u003c/strong\u003eDTA curves of indium melting and resolidification at heating/cooling rates from 0.5°C/s to 200°C/s. \u003cstrong\u003ed \u003c/strong\u003eThe melting points of indium are measured using DTA curves at various heating rates.\u003c/p\u003e","description":"","filename":"figure7.png","url":"https://assets-eu.researchsquare.com/files/rs-4662720/v1/e1b826722fcef5d6bce5077e.png"},{"id":61530327,"identity":"cff924aa-8285-4da4-a563-9abfd5d49e68","added_by":"auto","created_at":"2024-07-31 22:28:46","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":81389,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eComparison of thermogravimetric analysis results of CaC\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e2\u003c/strong\u003e\u003c/sub\u003e\u003cstrong\u003eO\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e4\u003c/strong\u003e\u003c/sub\u003e\u003cstrong\u003e·H\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e2\u003c/strong\u003e\u003c/sub\u003e\u003cstrong\u003eO using the cantilever in this work and the conventional instrument. \u003c/strong\u003eThe TGA curves show that the decomposition process of CaC\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e·H\u003csub\u003e2\u003c/sub\u003eO sample can be divided into two stages. At high heating rates, the thermal hysteresis of our cantilever is negligible compared with the commercial instrument.\u003c/p\u003e","description":"","filename":"figure8.png","url":"https://assets-eu.researchsquare.com/files/rs-4662720/v1/c324117f6beddf35b43ff22b.png"},{"id":79246177,"identity":"1cd57a35-7081-4038-a783-974368f6a5a6","added_by":"auto","created_at":"2025-03-26 07:06:05","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":6860360,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4662720/v1/cbbe8ff2-bdbd-4e07-95d3-dbec092fa4e3.pdf"},{"id":61530184,"identity":"be6bf280-9b8d-4a37-97f3-3636269eb15c","added_by":"auto","created_at":"2024-07-31 22:20:46","extension":"mp4","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":2184168,"visible":true,"origin":"","legend":"\u003cp\u003eSupporting Material S1\u003c/p\u003e\n\u003cp\u003eVideo of the indium melting during DTA measurement using our chips\u003c/p\u003e","description":"","filename":"indiummelting.mp4","url":"https://assets-eu.researchsquare.com/files/rs-4662720/v1/34c3b2a14578a49a3d68accd.mp4"}],"financialInterests":"(Not answered)","formattedTitle":"Thermocouple-Integrated Resonant Microcantilever for On-chip Thermogravimetric (TG) and Differential Thermal Analysis (DTA) Dual Characterization Applications","fulltext":[{"header":"Introduction","content":"\u003cp\u003eThermal analysis technologies evaluate temperature-dependent properties of substances under controlled conditions and are widely used in chemical engineering, food safety, and drug analysis.\u003csup\u003e\u003cspan additionalcitationids=\"CR2 CR3 CR4 CR5\" citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e\u003c/sup\u003e. Among the developed thermal analysis techniques, thermogravimetric analysis (TGA) and differential thermal analysis (DTA) stand out as two widely used characterization methods\u003csup\u003e\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e,\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e\u003c/sup\u003e. TGA is a classic characterization technique for measuring the mass change of materials during programmed heating in a particular atmosphere, and is frequently used to investigate the thermal stability of materials as well as the thermal properties of materials such as evaporation, decomposition, dehydration, and oxidation during the heating process.\u003csup\u003e\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e,\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e\u003c/sup\u003e. DTA primarily measures the temperature shifts of material in programmed temperatures, enabling the investigation of the endothermic or exothermic properties of materials during phase transitions or chemical reactions \u003csup\u003e\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e,\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e\u003c/sup\u003e. Therefore, the combined characterization of TGA and DTA techniques is conducive to establishing comprehensive, multidimensional thermal properties of materials\u003csup\u003e\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e\u003c/sup\u003e, which is of great significance for the rapidly advanced new functional materials and related research fields\u003csup\u003e\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eAlthough TGA and DTA instruments have been commercialized for decades, their inherent shortcomings have become increasingly evident in the rapid advancement of new functional materials and related research fields\u003csup\u003e\u003cspan additionalcitationids=\"CR14\" citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e\u003c/sup\u003e. Due to the bulk size of commercial DTA instruments, a large heat capacity is introduced, resulting in a power response typically in the mV/W level\u003csup\u003e\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e,\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e\u003c/sup\u003e. Therefore, to ensure sufficient DTA signal amplitude, the sample consumption of commercial DTA instruments should not be too small, typically on the milligram level\u003csup\u003e\u003cspan additionalcitationids=\"CR19\" citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e\u003c/sup\u003e. Meanwhile, the thermal balances used in current commercial instruments normally have mass sensitivities on the sub-microgram scale\u003csup\u003e\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e\u003c/sup\u003e, so mg-level samples are also required for commercial TGA measurement. The available commercial DTA and TGA instruments usually employ a crucible to hold the sample, preventing direct contact between the temperature measuring element and the sample itself, which introduces an inaccuracy in the temperature measurement. However, at high heating rates, mg-scale samples are difficult to heat uniformly, and a wide temperature distribution occurs, causing the TGA and DTA signals of the samples to have a hysteresis relative to the true values, and this hysteresis becomes more significant as the heating rate increases\u003csup\u003e\u003cspan additionalcitationids=\"CR23\" citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e\u003c/sup\u003e. Hence, commercial instruments typically limit the heating rate to less than 100\u0026ndash;200\u0026deg;C/min to ensure measurement accuracy\u003csup\u003e\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e,\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e\u003c/sup\u003e, resulting in time-consuming traditional TGA/DTA measurement, negatively affecting the efficiency of new materials development. Furthermore, the high sample volume of current commercial instruments is not conducive to measuring expensive, small batches of materials such as new drugs. Using a closed bulk furnace by commercial instruments to heat the sample presents a challenge in integrating the microscope for \u003cem\u003ein situ\u003c/em\u003e optical observation of sample appearance\u003csup\u003e\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e,\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e\u003c/sup\u003e. We note that based on MEMS (micro-electromechanical system) technology, many pairs of thermocouples have been integrated into chips, enabling on-chip DTA analysis capabilities\u003csup\u003e\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e,\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e,\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e\u003c/sup\u003e. However, such chips cannot accurately measure the sample mass, let alone perform on-chip TGA analysis. Our group initially used a micro-resonant cantilever integrated with on-chip heating and mass measurement functions, which enabled the on-chip TGA measurement of samples at the nanogram level\u003csup\u003e\u003cspan additionalcitationids=\"CR27 CR28\" citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e\u003c/sup\u003e. However, the cantilever can only determine the overall temperature by measuring the change in the resistance of the heater and cannot accurately measure the sample temperature. To date, the available MEMS sensors can only measure TGA or have DTA capabilities, but they have not yet been able to perform both functions on a single chip.\u003c/p\u003e \u003cp\u003eHerein, an integrated resonant microcantilever is proposed and developed to achieve dual thermal functions of TGA and DTA on a single MEMS chip. We integrated two pairs of polysilicon thermocouples into the resonant microcantilever, thus allowing further DTA measurement of samples while retaining the TGA function. The tiny structure of the microcantilever results in a significant reduction in the heat capacity of the chip, leading to a power responsivity at the V/W level, which is three orders of magnitude higher than that of commercial DTA instruments. Our chips achieve heating and cooling rates above 600\u0026deg;C/min, which is one to two orders of magnitude higher than conventional instruments, significantly improving the efficiency of TGA and DTA measurement. Reducing the volume of sample requirements allows for uniform heating during the rapid heating process. Furthermore, the sample is loaded directly onto the thermocouple integrated into the cantilever, ensuring highly accurate temperature detection. Thus, precise and efficient on-chip MEMS TGA and DTA characterization can be realized with our cantilever. Moreover, the integrated microcantilever has dimensions on the micron scale, and the integrated on-chip heater obviates the necessity for a heating oven, thus enabling the chip to be placed under a microscope for \u003cem\u003ein situ\u003c/em\u003e optical observation of the morphological evolutions that occur in the sample during thermal analysis. We have employed the above thermocouple-integrated resonant microcantilever chip for TGA or DTA measurement of a diverse range of materials, including metals (indium and tin standards) and calcium oxalate monohydrate (CaC₂O₄\u0026middot;H₂O).\u003c/p\u003e"},{"header":"Results","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eSensor Design and Fabrication\u003c/h2\u003e \u003cp\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ea shows a schematic illustration of the integrated cantilever. The sample is placed directly onto the free end of the cantilever, which has an integrated heater for on-chip heating and cooling. Two polysilicon thermocouples are also integrated into the cantilever. The hot junction is in the sample area, while the cold junction is on the bulk silicon substrate, ensuring accurate temperature detection. To separate the high-temperature zone from the low-temperature zone, an adiabatic window is placed in the center of the cantilever to block heat transfer from the free end to the fixed end. The detection of mass changes in loaded samples is based on the resonance frequency shift of the cantilever.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eAs shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eb, we use integrated thermocouples that rely on the Seebeck effect to detect the temperature difference between hot and cold junctions\u003csup\u003e\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e,\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e\u003c/sup\u003e. According to the Seebeck effect, the output voltage of thermocouples can be expressed as\u003csup\u003e\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e,\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e\u003c/sup\u003e:\u003c/p\u003e \u003cp\u003e \u003cspan class=\"InlineEquation\"\u003e \u003cspan class=\"mathinline\"\u003e\\(\\begin{array}{c}V=N\\left({{\\alpha }}_{B}-{{\\alpha }}_{A}\\right)\\left({T}_{hot}-{T}_{env}\\right)=N\\left({{\\alpha }}_{B}-{{\\alpha }}_{A}\\right)\\left({T}_{heat}-{T}_{env}+\\varDelta {T}_{loading}\\right)\\#\\left(1\\right)\\end{array}\\)\u003c/span\u003e \u003c/span\u003ewhere N is the number of thermocouple pairs, α\u003csub\u003eA\u003c/sub\u003e and α\u003csub\u003eB\u003c/sub\u003e are the Seebeck coefficient values of the two materials that form the thermocouples. \u003cem\u003eT\u003c/em\u003e\u003csub\u003ehot\u003c/sub\u003e is the temperature of the hot junction, which is composed of the temperature generated by the heater (\u003cem\u003eT\u003c/em\u003e\u003csub\u003eheat\u003c/sub\u003e) and the temperature difference caused by the loaded sample (Δ\u003cem\u003eT\u003c/em\u003e\u003csub\u003eloading\u003c/sub\u003e). T\u003csub\u003eenv\u003c/sub\u003e is the temperature of the environment. Therefore, we can measure the \u003cem\u003eT\u003c/em\u003e\u003csub\u003ehot\u003c/sub\u003e by recording the output voltage of thermocouples. To perform DTA measurement, two integrated cantilever chips with identical characteristics should be applied simultaneously under the same conditions to reduce the common mode noise and disturbances. One chip acts as a reference sensor, and the other as a test sensor for the load sample. Hence, the differential output voltage between reference and sensing can be expressed as:\u003cdiv id=\"Equa\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equa\" name=\"EquationSource\"\u003e\n$$\\begin{array}{c}\\varDelta V=N\\left({{\\alpha }}_{B}-{{\\alpha }}_{A}\\right)\\left({\\varDelta T}_{heat}+\\varDelta {T}_{loading}\\right)\\#\\left(2\\right)\\end{array}$$\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003eThe Δ\u003cem\u003eT\u003c/em\u003e\u003csub\u003eheat\u003c/sub\u003e is the difference between temperatures generated by heaters, caused by differences between chips in the specifications such as the heating resistance, the heat capacity, and the thermal conductance. It may be caused by some inevitable unevenness in the deposition rate and etching rate in the fabrication process. Therefore, it can be eliminated by measuring the same chips before loading the sample under the same conditions as the baseline for formal DTA measurement. This method allows us to determine the temperature difference produced by the loaded samples.\u003c/p\u003e \u003cp\u003eAs illustrated in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ec, we utilize the frequency change of the cantilever to quantify the mass change based on the conservation of mechanical energy at the resonant cantilever. When a small mass change occurs at the free end, and the mass change is much smaller than the effective mass of the cantilever, the relationship between the mass change and the 1st mode frequency shift can be expressed as\u003csup\u003e\u003cspan additionalcitationids=\"CR28\" citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e,\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e\u003c/sup\u003e.\u003cdiv id=\"Equb\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equb\" name=\"EquationSource\"\u003e\n$$\\begin{array}{c}\\varDelta m\\approx \\frac{k\\varDelta f}{2{\\pi }^{2}{{f}_{0}}^{3}}=2{m}_{eff}\\frac{\\varDelta f}{{f}_{0}}\\#\\left(3\\right)\\end{array}$$\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003ewhere Δ\u003cem\u003em\u003c/em\u003e is the tiny mass change on the free end, \u003cem\u003ek\u003c/em\u003e is the elastic coefficient of the cantilever, \u003cem\u003ef\u003c/em\u003e\u003csub\u003e0\u003c/sub\u003e is the resonant frequency of the cantilever before mass loading, Δ\u003cem\u003ef\u003c/em\u003e is the resonant frequency shift of the cantilever, and \u003cem\u003em\u003c/em\u003e\u003csub\u003eeff\u003c/sub\u003e is the effective mass. The Eq.\u0026nbsp;(3) shows that a small change in mass is directly proportional to the frequency change. In our chips, we can measure the mass change in real time by recording the frequency shift of the resonant cantilever, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eb.\u003c/p\u003e \u003cp\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ea shows the detailed structure of the integrated cantilever chips. The sample loading area is near the free end, where the surrounding bulk silicon is etched to reduce additional heat capacity. Molybdenum (Mo) is utilized to create microheaters for precise temperature control. The two hot junctions of the thermocouples are covered with semicircular molybdenum to ensure a uniform temperature across the sample region. For high temperature-sensitivity, we use n\u0026thinsp;+\u0026thinsp;and p\u0026thinsp;+\u0026thinsp;polysilicon to fabricate the thermocouple, which has a Seebeck coefficient significantly higher than the commonly used metals in IC fabrication\u003csup\u003e\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e,\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e\u003c/sup\u003e. In order to achieve both integrated resonance excitation and frequency readout functions, a silicon resistor is designed near the fixed end of the cantilever for electrothermal driving. Additionally, a Wheatstone bridge composed of silicon piezoresistors is fabricated near the fixed end to facilitate resonant frequency readout\u003csup\u003e\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e,\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e\u003c/sup\u003e. Due to the limitations of silicon resistors, which may not function properly at temperatures exceeding 125\u0026deg;C \u003csup\u003e\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e,\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e\u003c/sup\u003e, a thermal isolation window has been designed to separate the heater and piezoresistors. This design blocks direct thermal conduction within the cantilever while improving thermal resistance from the sample area to the surrounding environment. As a result, the design of the thermal isolation window helps to increase the power responsivity of the system.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eWe then perform finite element simulation to model the temperature distribution of the integrated cantilever using COMSOL Multiphysics analysis software. The software modeled the thermoelectrically generated heat using the electric current interface. The element also accounts for convective heat transfer in the air atmosphere and a fixed convective heat dissipation coefficient is set to reduce simulation time without compromising accuracy. The thermal conductivity of single-crystal silicon is adjusted for temperature based on the literature\u003csup\u003e\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e\u003c/sup\u003e to improve accuracy at high temperatures. Figure\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eb illustrates the simulation results for the overall temperature distribution on the surface of the cantilever when the temperature at the center of the sample region reaches 500\u0026deg;C. Additionally, we conducted a simulation to analyze the impact of the thermal isolation window, which blocks heat transfer from the free end to the fixed end. Figure\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ec presents the effect of the thermal isolation window on the temperature distribution along the center axis of the cantilever. With the isolation window, the temperature around the Wheatstone bridge remains below 65\u0026deg;C as the temperature at the free end exceeds 500\u0026deg;C. In contrast, without the isolation window, the temperature around the Wheatstone bridge increases to 160\u0026deg;C, which could lead to p-n junction leakage. The simulation results demonstrate effective thermal isolation between the free and fixed ends, protecting the resonant excitation and readout silicon resistors at high operating temperatures. In Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ed, the temperature distribution of the sample loading region along the horizontal axis is shown at different heating voltages. The simulation results indicate a uniform temperature distribution in the center of the sample loading region, with a variation of within \u0026plusmn;\u0026thinsp;1%.\u003c/p\u003e \u003cp\u003eOur chips are produced on 4-inch (100) SOI wafers, enabling precise control over the cantilever layer thickness of 3 \u0026micro;m, a handle layer thickness of 500 \u0026micro;m, and a box layer thickness of 700 nm. The detailed fabrication process is shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e: (a) The thermal SiO\u003csub\u003e2\u003c/sub\u003e of 350nm is fabricated through a heating oxidation furnace. After photolithography and RIE etch of SiO\u003csub\u003e2\u003c/sub\u003e, a pool is defined by KOH wet etching for the sample loading region. (b) The silicon resistors of resonant excitation and readout resistors (Wheatstone bridge) are defined by photolithography, ion-implantation, and diffusion. (c-d) After depositing 200nm of SiNx and 500nm of polysilicon films by LPCVD, the main part of polysilicon thermocouples is fabricated through ion implantation, diffusion, and RIE sequentially. A 300nm SiNx film is then deposited to protect the thermocouples. (e) After etching the connection window of the polysilicon thermocouple and silicon resistors, the Mo films are patterned using the lift-off process to create microheaters and connect the thermocouples. Subsequently, the Al films are patterned using the lift-off process to establish electrical connections for the silicon resistors. (f) Depositing a 200nm PECVD Si\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e layer provides protection against oxidation and electrical isolation. (g) A RIE process of dielectric layers is followed by DRIE of the device layer and RIE of the box layer to form the shape of the resonant cantilever. (h) The handle layer is removed from the back side using a DRIE process, thus releasing the cantilever.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003eCharacterization of the Integrated Cantilever Chips\u003c/h2\u003e \u003cp\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ea depicts the morphological image of the manufactured resonant cantilevers. The cantilever measures 340 \u0026micro;m in length, 190 \u0026micro;m in width, and 3 \u0026micro;m in thickness. The sample loading area has a diameter of 60 \u0026micro;m, and the thermal isolation window measures 100 \u0026micro;m \u0026times; 90 \u0026micro;m. The SEM image of the cantilever in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ea clearly reveals the structure and morphology of the integrated thermocouple, heater, resonant excitation/readout resistor, and sample loading area. Figure\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eb illustrates the wafer-level fabrication of the cantilever chips on a 4-inch SOI wafer. Figure\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ec schematically depicts the test system for TGA and DTA measurements. The resonant excitation and readout resistors of the sensing chip are connected to a phase-locked-loop (PLL) circuit for tracking the resonant frequency. The output voltage from the thermocouples and integrated heaters of both chips is connected to a signal readout and heater drive circuit, which records and controls the temperature of the sample region. Both circuits are linked to a computer for data recording and further processing.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe temperature dependence of the chip was first assessed by measuring the temperatures of the hot junction at various heating voltages using a non-contact infrared thermal imager with a spatial resolution of 20 \u0026micro;m. Simultaneously, the test system recorded the output voltage of the thermocouples. Figure\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003ea shows the measured and simulated temperatures of the sample loading area as a function of the heating voltage, and the agreement is very good, indicating that our simulation is reliable. The sample region can be heated up to 530℃ under a heating voltage of 6.2V. Meanwhile, Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003eb shows the corresponding relationship between the output voltage and heating power of the seven chips. The average power response of each chip is 6.1V/W, which is three orders of magnitude higher than that of traditional instruments (generally in the mV/W level)\u003csup\u003e\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e,\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e\u003c/sup\u003e, and the relative standard deviation is only 3%, indicating strong consistency between different chips. In Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003ec, the output voltage of thermocouples is shown for different measured temperatures. The output voltage demonstrates a linear response to the temperature, with a high-temperature responsivity of 0.73mV/K. The root-mean-square (\u003cem\u003erms\u003c/em\u003e) voltage noise of the MEMS thermocouples can be expressed as follows:\u003cdiv id=\"Equc\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equc\" name=\"EquationSource\"\u003e\n$$\\begin{array}{c}{V}_{noise,rms}=\\sqrt{4{k}_{B}TRB}\\#\\left(4\\right)\\end{array}$$\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003ewhere \u003cem\u003ek\u003c/em\u003e\u003csub\u003eB\u003c/sub\u003e is the Boltzmann\u0026rsquo;s constant, \u003cem\u003eT\u003c/em\u003e is the room temperature, \u003cem\u003eR\u003c/em\u003e is the thermocouples resistance (10kΩ), and \u003cem\u003eB\u003c/em\u003e is the system bandwidth (400Hz) \u003csup\u003e\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e,\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e\u003c/sup\u003e. According to Eq.\u0026nbsp;(3), we can have a \u003cem\u003erms\u003c/em\u003e voltage noise of 0.26\u0026micro;V for our chips. Therefore, we can calculate a noise equivalent temperature (NET) of 2.8mK, based on the 8\u0026times;V noise, \u003cem\u003erms\u003c/em\u003e, and temperature responsivity\u003csup\u003e\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e\u003c/sup\u003e. We also measure the change in heating resistance with the working temperature, as illustrated in Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003ed, indicating a TCR (temperature coefficient of resistance) of 0.0014/K.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThen, the mass-sensing properties of the fabricated cantilevers are calibrated. A flowing DC-biased AC is applied to the excitation resistor, and the Wheatstone bridge is also connected to the PLL interface circuit. In this way, we can measure the real-time frequency shift. The resonant frequency of our cantilever is approximately 35 kHz, with a \u003cem\u003eQ\u003c/em\u003e factor of 190. To calibrate the mass sensitivity of our cantilever, we measure the resonant frequency of the cantilever before and after placing a standard polystyrene (PS) sphere on the sample region, as illustrated in Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003ea-b. The diameter of the standard PS sphere is 25 \u0026micro;m, and the density is 1.05 g/cm\u003csup\u003e3\u003c/sup\u003e. A resonant frequency change of 399 Hz is measured after loading the standard PS sphere, which leads to a mass responsivity of 0.090 Hz/pg for the cantilever. The noise floor of the frequency signal is approximately 0.5 Hz, leading to a mass resolution of 5.5 pg. Therefore, our chips can conduct thermogravimetric analysis with ng-level samples. When the sample region of the cantilever is heated from room temperature to 400℃, only a slight frequency shift of 50 Hz is measured, equivalent to a mass change of 0.56 ng.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003eDTA Measurement Using Integrated Cantilever Chips\u003c/h2\u003e \u003cp\u003eMetal standards with a fixed melting point are commonly used to calibrate DTA measurements. In this work, we have selected indium (In) and tin (Sn) standards to validate our DTA measurement performance. As mentioned above, two chips are used simultaneously in DTA measurement. One chip contains a sample, while the other is left empty. The DTA measurements are carried out at various heating rates in an air atmosphere. Because our cantilevers are small, we place them under a microscope to observe the morphological changes of the samples \u003cem\u003ein situ\u003c/em\u003e during the DTA measurements.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eWe first measure the melting process of In and Sn at a heating rate of 10\u0026deg;C/s. The results are shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003ea-b. We can observe the sharp heat absorption peak caused by the melting process. The video in Supporting Material S1 and the insets in Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003ea show the \u003cem\u003ein situ\u003c/em\u003e optical images of the indium melting process. The indium undergoes a noticeable morphological change after reaching its melting point. Based on the heat absorption peak in the measured DTA curve, we can calculate the melting point of the metal using our chips\u003csup\u003e\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e\u003c/sup\u003e. The measured melting point of indium is 157.7\u0026deg;C, which is only 1.1\u0026deg;C higher than the standard value of 156.5\u0026deg;C in literature\u003csup\u003e\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e,\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e\u003c/sup\u003e. As for tin, the melting point is measured as 231.7℃, only 0.2℃ smaller than the standard valve (231.9℃)\u003csup\u003e\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e\u003c/sup\u003e. The results presented in Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003ea-b confirm the temperature accuracy of our chips.\u003c/p\u003e \u003cp\u003eWe further test the indium melting and solidification process at different heating and cooling rates from 1\u0026deg;C /s to 200\u0026deg;C /s. The heat absorption and release during melting and solidification processes induce sharp peaks in the DTA curves, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003ec. As the rate of temperature rise and fall increases, the DTA signal becomes larger, thereby facilitating the measurement of small heat absorption or exothermic processes. We also calculate the melting point of indium at different heating rates, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003ed. The melting point at 200\u0026deg;C/s exhibits only a 5\u0026deg;C difference compared to the melting point at 1\u0026deg;C /s. The results demonstrate that the chip exhibits small thermal hysteresis even at rapid temperature changes.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003eTGA Measurement Using Integrated Cantilever Chips\u003c/h2\u003e \u003cp\u003eTo demonstrate the technical merit of our integrated cantilever in TGA measurement, inorganic crystals with known molecular structures are selected. CaC\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e∙H\u003csub\u003e2\u003c/sub\u003eO is a standard substance for evaluating TGA measurement. The TGA measurement by our cantilevers is performed at a heating rate of 600\u0026deg;C/min in an air atmosphere. We also measure the same sample with a conventional TGA instrument at heating rates of 10℃/min and 200℃/min. The results are plotted together in Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003e for comparison. Two stages of decomposition can be observed in the TGA curves measured from room temperature to 620\u0026deg;C. The first stage can be assigned to the loss of water of crystallization with a weight loss of 12.2%. The second stage shows a weight loss of 20.3%, which indicates CaC\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e decomposed into CaCO\u003csub\u003e3\u003c/sub\u003e. Both decomposition-induced weight losses are consistent with the theoretical values (12.32%, 19.16%)\u003csup\u003e34,38\u003c/sup\u003e. When the CaC\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e∙H\u003csub\u003e2\u003c/sub\u003eO sample was analyzed using a conventional TGA instrument (NETZSCH TG 209 F1 Libra), the TGA curve obtained at a heating rate of 200\u0026deg;C/min showed a significant hysteresis compared to the test at a heating rate of 10\u0026deg;C/min. Fortunately, even when heating at a high rate of 600\u0026deg;C/min, the TGA results obtained with the cantilever closely match those obtained with a conventional TGA instrument using a heating rate of 10\u0026deg;C/min. The results suggest that the thermal hysteresis phenomenon of the cantilever is minimal in MEMS TGA analysis, and it dramatically improves the efficiency of the TGA analysis.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e"},{"header":"Conclusion","content":"\u003cp\u003eIn summary, we have developed and fabricated an integrated resonant microcantilever for performing both thermogravimetric analysis (TGA) and differential thermal analysis (DTA) measurements. Each microcantilever chip includes a microheater, resonance excitation/readout resistors, and thermocouples to enable controlled heating, precise mass detection at the picogram level, and accurate temperature measurement. Our cantilevers show a power responsivity of 6.1V/W, temperature sensitivity of 0.73mV/\u0026deg;C, and temperature resolution of 2.8mK. Our cantilevers also have a mass sensitivity of 0.09 Hz/pg and a mass resolution of 5.5pg. We then performed TGA measurements on CaC\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e∙H\u003csub\u003e2\u003c/sub\u003eO and DTA measurements on indium and tin metal standards. Our test results demonstrate that our chip can perform high-precision TGA and DTA analysis. Our chip has faster heating/cooling speeds and consumes fewer samples than conventional TGA and DTA instruments. Our integrated cantilever device is expected to enable efficient TGA and DTA testing in various essential application areas in physics, chemistry, metallurgy, pharmaceuticals, and nanotechnology.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003eAUTHOR INFORMATION\u003c/p\u003e\n\u003cp\u003eCorresponding Author\u003c/p\u003e\n\u003cp\u003e*Corresponding\u0026nbsp;author\u003c/p\u003e\n\u003cp\u003e* Pengcheng Xu \u0026minus; State Key Lab of Transducer Technology, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050, China; University of Chinese Academy of Sciences, Beijing 100049, China; Email: [email protected]\u003c/p\u003e\n\u003cp\u003e* Xinxin Li \u0026minus; State Key Lab of Transducer Technology, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050, China; University of Chinese Academy of Sciences, Beijing 100049, China; Email: [email protected]\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;Funding Sources\u003c/p\u003e\n\u003cp\u003eThis research was funded by the National Key R\u0026amp;D Program of China (2021YFB3200800), National Natural Science Foundation of China (62227815, 61831021, 62271473, 62104241, U21A20500), and Innovation Team and Talents Cultivation Program of National Administration of Traditional Chinese Medicine (ZYYCXTD-D-202002, ZYYCXTD-D-202003).\u003c/p\u003e\n\u003cp\u003eNotes\u003c/p\u003e\n\u003cp\u003eThe authors declare no competing financial interest.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eHassid, A., Klinger, M., Krzack, S. \u0026amp; Cohen, H. 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Anal Chem 69, 1485-1491, (1997).\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":"microsystems-and-nanoengineering","isNatureJournal":false,"hasQc":false,"allowDirectSubmit":false,"externalIdentity":"micronano","sideBox":"Learn more about [Microsystems \u0026 Nanoengineering](http://www.nature.com/micronano/)","snPcode":"41378","submissionUrl":"https://mts-micronano.nature.com/","title":"Microsystems \u0026 Nanoengineering","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"ejp","reportingPortfolio":"Nature AJ","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Thermogravimetric analysis, Differential thermal analysis, resonant cantilever, thermocouple, scientific instrument","lastPublishedDoi":"10.21203/rs.3.rs-4662720/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4662720/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThis work presents an integrated microsensor that combines the dual characterization capabilities of thermogravimetric analysis (TGA) and differential thermal analysis (DTA). We integrated two pairs of thermocouples, heating resistors, and resonant drive/detection resistors into one microcantilever to achieve programmable temperature control, temperature change, and mass detection in a single chip. Our chip can achieve heating and cooling rates above 600\u0026deg;C/min, which is significantly faster than commercial instruments with satisfactory measurement accuracy. The integrated polysilicon thermocouples bring high power responsivity of 6V/W, making them suitable for highly sensitive DTA measurements on a chip. Moreover, the cantilever offers picogram (10\u003csup\u003e-12\u003c/sup\u003eg) level mass resolution, reducing sample consumption from milligrams to nanogram levels. Additionally, the on-chip sample heating allows for easy observation of sample morphological evolution during heating under an optical microscope. We validated the dual functionality by conducting TGA measurements on a standard sample of calcium oxalate monohydrate (CaC\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e∙H\u003csub\u003e2\u003c/sub\u003eO) and DTA measurements on high-purity indium (In) and tin (Sn). The results indicate consistent measurements with the true values of the standard sample and high measurement efficiency. Our integrated cantilever chip is anticipated to have broad applications in high-performance and efficient TGA and DTA characterization.\u003c/p\u003e","manuscriptTitle":"Thermocouple-Integrated Resonant Microcantilever for On-chip Thermogravimetric (TG) and Differential Thermal Analysis (DTA) Dual Characterization Applications","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-07-31 22:20:41","doi":"10.21203/rs.3.rs-4662720/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"revise","date":"2024-08-06T00:47:43+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"This content is not available.","date":"2024-07-31T00:33:41+00:00","index":2,"fulltext":"This content is not available."},{"type":"editorInvitedReview","content":"This content is not available.","date":"2024-07-17T06:15:19+00:00","index":3,"fulltext":"This content is not available."},{"type":"editorInvitedReview","content":"This content is not available.","date":"2024-07-15T03:50:23+00:00","index":1,"fulltext":"This content is not available."},{"type":"reviewerAgreed","content":"This content is not available.","date":"2024-07-11T11:43:38+00:00","index":3,"fulltext":"This content is not available."},{"type":"reviewerAgreed","content":"This content is not available.","date":"2024-07-07T13:38:55+00:00","index":2,"fulltext":"This content is not available."},{"type":"reviewerAgreed","content":"This content is not available.","date":"2024-07-07T09:37:56+00:00","index":1,"fulltext":"This content is not available."},{"type":"reviewersInvited","content":"","date":"2024-07-07T06:53:53+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2024-07-01T06:27:01+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2024-06-30T12:38:17+00:00","index":"","fulltext":""},{"type":"submitted","content":"Microsystems \u0026 Nanoengineering","date":"2024-06-30T12:38:16+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"microsystems-and-nanoengineering","isNatureJournal":false,"hasQc":false,"allowDirectSubmit":false,"externalIdentity":"micronano","sideBox":"Learn more about [Microsystems \u0026 Nanoengineering](http://www.nature.com/micronano/)","snPcode":"41378","submissionUrl":"https://mts-micronano.nature.com/","title":"Microsystems \u0026 Nanoengineering","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"ejp","reportingPortfolio":"Nature AJ","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"52fa66fc-fd69-4193-8424-23d9b5e425b2","owner":[],"postedDate":"July 31st, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2025-03-26T07:05:55+00:00","versionOfRecord":{"articleIdentity":"rs-4662720","link":"https://doi.org/10.1038/s41378-024-00828-9","journal":{"identity":"microsystems-and-nanoengineering","isVorOnly":false,"title":"Microsystems \u0026 Nanoengineering"},"publishedOn":"2025-03-26 04:00:00","publishedOnDateReadable":"March 26th, 2025"},"versionCreatedAt":"2024-07-31 22:20:41","video":"","vorDoi":"10.1038/s41378-024-00828-9","vorDoiUrl":"https://doi.org/10.1038/s41378-024-00828-9","workflowStages":[]},"version":"v1","identity":"rs-4662720","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4662720","identity":"rs-4662720","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}