Mechanically Durable Balsa Wood-PDMS Composites for Self-Powered Vibration Energy Harvesting

Mechanically Durable Balsa Wood-PDMS Composites for Self-Powered Vibration Energy Harvesting | 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 Mechanically Durable Balsa Wood-PDMS Composites for Self-Powered Vibration Energy Harvesting Yang Hu, Quanling Yang, Hongmei Qin, Chuanxi Xiong, Zhuqun Shi This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7320337/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract With the continuous advancement of social technology, fossil fuel shortages and environmental pollution are becoming increasingly severe, leading to growing attention toward renewable energy technologies. Consequently, the development of novel eco-friendly energy devices holds significant importance. As a type of innovative eco-friendly energy device, piezoelectric materials have garnered extensive scholarly interest due to their ability to harvest energy from the environment (such as mechanical vibrations, sound waves, and human activities). Herein, we selects natural balsa wood as the substrate material in this study. After undergoing purification treatment to remove non-cellulosic impurities, the cellulose within the balsa wood retains an aerogel structure characterized by a high specific surface area and porosity. Furthermore, The cellulose/PDMS-20 aerogel samples, prepared under the condition of PDMS negative-pressure loading for 20 minutes, exhibit excellent compressive modulus and optimal triboelectric output performance, with an output voltage as high as 1.9 V and a short-circuit current of 26 nA, demonstrating promising application prospects in the field of wearable self-powered sensing. Balsa wood PDMS Piezoelectric sensor Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Introduction Due to the shortage of fossil energy resources and environmental concerns, there is an increasing demand for alternative renewable energy sources (Lior 2010 ; Zhang et al. 2023 ; Mo et al. 2022 .). Mechanical energy, as a renewable and sustainable resource, is widely distributed in the environment and exists in various forms such as human motion, vibration, wind, and sound. However, a significant portion of mechanical energy remains untapped. In recent years, diverse methods have been developed to directly harness mechanical energy or convert it into other forms (Lin et al. 2013 ; Zheng et al. 2022 ). Nanogenerators (NGs), capable of harvesting energy from environmental sources including mechanical vibrations (Qin et al. 2008 ), heat (Hu et al. 2010 ; Lee et al. 2014 ), sound waves (Lee et al. 2013 ), and human activities (Lee et al. 2012 ), have garnered considerable attention from researchers. Since 2006, NGs based on ZnO nanowires, which can convert mechanical energy into electrical energy, have been extensively studied (Qin et al. 2008 ). The development of ZnO nanowire-based NGs has achieved output power levels in the sub-milliwatt range, sufficient to power numerous small-scale electronic devices such as commercial light-emitting diodes (Yang et al. 2012 ), various sensors (Lin et al. 2013 ), and liquid crystal displays (Hu et al. 2010 ). Nevertheless, such NGs typically require complex fabrication and manufacturing processes, thereby limiting their mechanical flexibility and potential applications. Biomass-based piezoelectric materials, as a novel category of piezoelectric materials, have been investigated by researchers (Xu et al. 2025 ) due to their environmentally friendly nature, biodegradability, biocompatibility, and abundant availability. As piezoelectric materials, cellulose-based materials have emerged as a research hotspot (Trellu et al. 2023 ) owing to their unique mechanical properties, ease of processing and preparation, and favorable piezoelectric performance. Currently, cellulose-based piezoelectric materials are developing rapidly, and several achievements have been made in the field of piezoelectric materials based on cellulose. Cellulose, with its abundant reserves primarily found in plant cell walls, is widely available and inexpensive. It also exhibits both direct and converse piezoelectric effects (Chen et al. 2024 ). The fundamental chemical structure unit of cellulose mainly consists of glucose molecules linked by glycosidic bonds (Abe et al. 2011; Isogai et al. 2011 ). In addition to cellulose, which constitutes a significant portion of natural plants, lignin and hemicellulose are also present (Bertolo et al. 2025 ). These components play roles in supporting plant growth and providing mechanical strength, but they lack favorable flexibility and piezoelectric properties. By removing lignin and hemicellulose, high-performance cellulose can be obtained (Tezcan et al. 2017). Therefore, cellulose can be extracted from natural plants by removing lignin and hemicellulose. Freeze-drying technology is commonly employed for the preparation of cellulose aerogels (Yahya et al. 2015 ; Rahmanian et al. 2021 Shi et al. 2018 ). Through composite material technology, which involves combining cellulose with other materials, piezoelectric materials with excellent performance can be achieved. Cellulose aerogels and their composites boast unique advantages such as biodegradability, biocompatibility, and excellent mechanical properties, making them highly suitable for material selection in flexible piezoelectric sensor devices. Cellulose exhibits intrinsic piezoelectric properties, and its distinctive nanoscale porous structure can generate pore electrets with piezoelectric responses, endowing it with broad application prospects in flexible piezoelectric sensor devices (Li et al. 2018; Zheng et al. 2016 ). To further enhance the compressive resistance of the overall piezoelectric sensor device and improve the charge conduction capability of the responsive charges within the aerogel network, polymers with superior mechanical properties can be introduced for compounding. Polydimethylsiloxane (PDMS) is a silicon-containing polymer material that possesses excellent corrosion resistance, thermal stability, unique flexibility, and mechanical properties. Hu et al. (Hu et al. 2011) utilized the good piezoelectric properties of PDMS to compound it with lead zirconate titanate (PZT) nanowires, resulting in a composite film with favorable piezoelectric characteristics. The transmittance of the piezoelectric composite film prepared via dielectrophoresis technology reached 72%, a significant improvement compared to the 42% transmittance of non-oriented piezoelectric films. The piezoelectric nanogenerator based on the uniformly oriented PZT nanowire/PDMS composite was capable of outputting a voltage of 0.60 V and a current of 3.95 nA, representing increases of 88% and 62%, respectively, compared to the non-oriented piezoelectric film. Additionally, they has successfully applied this composite in the field of smartphone privacy screens, achieving favorable results. In this study, we utilized balsa wood as the source of cellulose and introduced PDMS to enhance the mechanical properties of the aerogel, successfully developing a piezoelectric nanogenerator with high mechanical strength. The specific procedures were as follows: First, the natural balsa wood raw material was purified. Subsequently, the substances within it were replaced with tert-butyl alcohol, and then a freeze-drying process was employed to obtain cellulose aerogel with a high specific surface area. Next, the cellulose aerogel was immersed in a PDMS solution, and through vacuum infiltration technology, PDMS was fully filled into the pores of the balsa wood cellulose aerogel, resulting in the preparation of cellulose/PDMS aerogel. The experimental results revealed that the Cellulose/PDMS-20 aerogel sample prepared under a 20-minute PDMS negative pressure loading condition exhibited excellent compressive modulus and optimal triboelectric output performance (with an output voltage as high as 1.9V and a short-circuit current of 26nA). This performance was significantly superior to the 1.65V output voltage of the cellulose acetate/cellulose nanocrystal composite nanofiber membrane (Sun et al. 2022 ) and was comparable to the 2.0V output voltage of cotton nanofibers (Wang et al. 2022 ). It is noteworthy that in this study, after purifying natural cellulose raw materials, we directly incorporated the elastomer PDMS for mechanical reinforcement and utilized the composite as a piezoelectric material, without the need to modify the natural cellulose. Moreover, this method can further enhance the overall piezoelectric response capability of the device by introducing piezoelectric ceramics, thereby expanding the application scope of bio-based materials in the piezoelectric field. It holds significant theoretical and practical implications for the development of environmentally friendly and sustainable green energy technologies. Experimental Materials Natural Balsa Wood was provided by Nippon Paper Industries (Tokyo, Japan). NaClO 2 was bought from Aladdin (Shanghai, China). PDMS prepolymer and crosslinking agent were purchased from Dow chemistry (China). Acetic acid, ethanol and tert-butanol were purchased from Taicang Hushi Co., Ltd. (China). Sodium hydroxide and other pharmaceutical reagents were purchased from Aladdin (China). The purification process of balsa wood Lignin in balsa wood was oxidized using a sodium chlorite and acetic acid aqueous system to obtain lignin-free balsa wood. Specifically, 5 g of balsa wood cubes (2 cm × 2 cm × 2 cm) were accurately weighed and added to a 300 ml conical flask. Then, 160 ml of water was accurately measured and added to the flask, followed by the addition of 0.5 ml of acetic acid using a plastic dropper. The flask containing the sample was placed in a 75 ℃ water bath for heating. After a certain period, 1.5 g of NaClO₂ was added to the flask, which was then covered with a smaller conical flask of appropriate diameter. The flask was shaken every five minutes to ensure a thorough reaction. After one hour of reaction, an additional 0.5 ml of CH₃COOH was added using a plastic dropper, followed by the addition of another 1.5 g of NaClO₂. The reaction was allowed to proceed for 1 h in the flask, with shaking every five minutes to ensure complete reaction. This process was repeated four times. Subsequently, the mixture was cooled in an ice-water bath, and after a period, suction filtration was performed. The residue was washed approximately five times with deionized water to obtain lignin-free balsa wood. Hemicellulose in balsa wood was removed using a concentrated sodium hydroxide (NaOH) solution. Specifically, 30 ml of 17.5% NaOH solution and 150 ml of 9.5% NaOH solution were accurately weighed and prepared. The lignin-free balsa wood prepared in the previous stage was placed in a beaker. Initially, 30 ml of 17.5% NaOH solution was added (in portions, with magnetic stirring for 2–3 minutes between additions), and the beaker was allowed to mercerize at room temperature for 45 minutes. Subsequently, 30 ml of water was added to the beaker, followed by magnetic stirring for 2 minutes. The mixture was then filtered using a Buchner funnel. The resulting solid was washed three times with 50 ml of 9.5% NaOH solution and subsequently with deionized water until neutrality was achieved, yielding balsa wood cellulose. Preparation of Cellulose Aerogel and PDMS/Cellulose Composite Aerogel The preparation of cellulose aerogel and PDMS/cellulose composite aerogel is described as follows. The balsa wood cellulose obtained previously was subjected to ethanol replacement to remove water. Initially, a 10% ethanol-water solution was prepared, and the balsa wood was placed in this solution and shaken on a rocker to ensure thorough replacement. After one hour, the ethanol concentration was sequentially increased to 30%, 50%, 70%, and 90%, with each replacement step lasting one hour. Finally, the balsa wood cellulose was placed in pure ethanol overnight. Subsequently, tert-butanol was used to replace the ethanol solvent. The ethanol was replaced with tert-butanol in a stepwise manner (10%, 30%, 50%, 70%, 90%, and finally pure tert-butanol), with each replacement step lasting one hour on a rocker until the balsa wood cellulose was left in pure tert-butanol overnight. After the replacement process, the material was placed in a refrigerator for freezing and subsequently freeze-dried at -45°C for two days to obtain the cellulose aerogel (Zhang et al. 2025 ), denoted as "Cellulose”. The natural balsa wood was denoted as "Wood". To prepare the PDMS/cellulose composite aerogel, a PDMS mixture was prepared at room temperature using PDMS prepolymer and PDMS curing agent (uncured or slowly curing at room temperature). The balsa wood cellulose aerogel was placed in the PDMS solution, and PDMS was infiltrated into the pores of the cellulose aerogel using vacuum. This process was repeated 3–5 times. The infiltrated aerogel was then placed in an oven for curing, followed by demolding to obtain the PDMS/cellulose composite aerogel. By controlling the duration of PDMS infiltration under vacuum, PDMS/cellulose aerogels with varying PDMS contents were prepared. The aerogels infiltrated with PDMS for 5, 10, 20, and 30 minutes under vacuum were denoted as Cellulose/PDMS-5, Cellulose/PDMS-10, Cellulose/PDMS-20, and Cellulose/PDMS-30, respectively. Characterization The prepared samples of cellulose, PDMS, cellulose/PDMS-5, cellulose/PDMS-10, cellulose/PDMS-20 and cellulose/PDMS-30 were tested using a Fourier Transform Infrared (FTIR) spectrometer from Nicolet Corporation (USA). The test samples were 1 cm × 1 cm thin films, and measurements were conducted in transmission mode (in the near-infrared region). Tests were carried out using an X-ray diffractometer from Rigaku Corporation (Japan). The sample dimensions (length × width) of cellulose, PDMS, cellulose/PDMS-5, cellulose/PDMS-10, cellulose/PDMS-20 and cellulose/PDMS-30 were less than 1 cm, and their height was less than 0.5 cm. Measurements were performed in reflection mode with a scanning range of 2θ = 5° − 75°. Testing was conducted using a Scanning Electron Microscope (SEM, Hitachi S-4800) from a Japanese company. Cross-sectional images of cellulose, cellulose/PDMS-5, cellulose/PDMS-10, cellulose/PDMS-20 and cellulose/PDMS-30 were captured and scanned. The open-circuit voltage (V) and short-circuit current (A) of wood, cellulose, PDMS, cellulose/PDMS-5, cellulose/PDMS-10, cellulose/PDMS-20 and cellulose/PDMS-30 were measured using a CHI-660E electrochemical workstation from Shanghai Chenhua Instrument Co., Ltd. Instruments from MTS Systems Corporation were used to test the samples. Cellulose, PDMS, cellulose/PDMS-5, cellulose/PDMS-10, cellulose/PDMS-20 and cellulose/PDMS-30 were cut into 20 mm × 10 mm strips and placed in a universal testing machine. The initial compression rate was set at 1 mm/min for compression testing (conducted at room temperature and 50% humidity). The specific surface area of cellulose, cellulose/PDMS-5, cellulose/PDMS-10, cellulose/PDMS-20 and cellulose/PDMS-30 was analyzed in powder form using an ASAP 2460 automatic specific surface area and porosity analyzer from Micromeritics Instrument Corporation (USA). Cellulose/PDMS-5 and cellulose/PDMS-30 were analyzed using an ESCALAB 250Xi X-ray Photoelectron Spectrometer (XPS) from Thermo Fisher Scientific (USA). Results and Discussion The Structures of Cellulose/PDMS composite aerogels Figure 1 illustrates the FTIR spectra of Cellulose, PDMS, Cellulose/PDMS-5, Cellulose/PDMS-10, Cellulose/PDMS-20, and Cellulose/PDMS-30 within the range of 4000–500 cm⁻¹. It can be observed that Cellulose exhibits characteristic peaks at 3343 cm⁻¹, 2910 cm⁻¹, and 1058 cm⁻¹, corresponding to the stretching vibrations of O-H, C–H, and C–O bonds in the cellulose molecular structure, respectively. These principal characteristic peaks remain largely unchanged with the vacuum loading of PDMS. Conversely, PDMS displays characteristic peaks at 2962 cm⁻¹, 1000–1100 cm⁻¹, and 790 cm⁻¹, corresponding to the stretching vibrations of C-H, Si-O, and Si-C bonds, respectively. In the FTIR spectra of Cellulose/PDMS-5, Cellulose/PDMS-10, Cellulose/PDMS-20, and Cellulose/PDMS-30, characteristic peaks from both materials can be simultaneously observed, indicating a relatively stable composite formation between the two materials. However, it is notable that in the Cellulose/PDMS-30 composite, as the duration of vacuum loading with PDMS increases (i.e., as PDMS content rises), the intensity of the O-H characteristic peak of cellulose slightly diminishes, possibly due to hydrogen bonding between PDMS and cellulose (Trellu et al. 2023 ). Figure 2 displays the X-ray diffraction (XRD) patterns of cellulose, PDMS, cellulose/PDMS-5, cellulose/PDMS-10, cellulose/PDMS-20, and cellulose/PDMS-30 within the 2θ range of 5° to 75°. Most of the cellulose within the composite aerogels exhibits a Type II crystalline structure. In the XRD pattern of the cellulose aerogel, a distinct diffraction peak is observed at 2θ = 12.5°, corresponding to the (1–10) plane of cellulose II crystals. Additionally, a prominent diffraction peak is detected near 2θ ≈ 21°, representing a broadened peak associated with the (110) and (020) planes of cellulose II crystals (Shi et al., 2014 ). In comparison, cellulose is a polymeric material with relatively high crystallinity, while PDMS exhibits low crystallinity, displaying only a broad and low-intensity diffraction peak near 2θ ≈ 21°, which is relatively close in position to the characteristic peak of cellulose. Therefore, when PDMS is introduced into the cellulose aerogel, the XRD pattern of the resulting composite primarily features the crystalline characteristic peaks of cellulose, indicating that PDMS has been thoroughly dispersed and embedded within the cellulose aerogel matrix of the composite. Furthermore, as the vacuum filling time of PDMS increases, the characteristic peaks in the XRD pattern remain largely unchanged, suggesting that the crystalline state of the cellulose aerogel remains unaltered. Figure 3 presents cross-sectional images of Cellulose, Cellulose/PDMS-5, Cellulose/PDMS-10, Cellulose/PDMS-20, and Cellulose/PDMS-30. In Fig. 3 a-b, the highly porous structure within the cellulose aerogel material is observable, alongside its layered architecture (which is delimited by cell walls into stratified layers). The layered, porous cellulose aerogel, segmented by cell walls, also imparts compressibility to the material. As PDMS is introduced in Fig. 3 c-f, the porous structure within the cellulose aerogel gradually becomes filled, with the SEM images clearly demonstrating the densification of the material's porous framework by PDMS. The porous structures of Cellulose, Cellulose/PDMS-5, Cellulose/PDMS-10, Cellulose/PDMS-20, and Cellulose/PDMS-30 reveal a progressive reduction in porosity of the composite aerogels as the PDMS soaking/loading duration increases. Despite PDMS infiltration, the material retains its intact layered structure, as evidenced by the discernible cell walls in the SEM images, indicating a robust integration of the two components to form a structurally cohesive composite aerogel material. As depicted in Fig. 4 a, the Cellulose aerogel without PDMS loading possesses the highest nitrogen adsorption sites. Correspondingly, as shown in Fig. 4 b, the Cellulose aerogel without PDMS loading exhibits the highest specific surface area, reaching up to 7.1 m²/g. Meanwhile, Fig. 4 a illustrates that with the increase in PDMS loading time, the nitrogen adsorption sites of the composite Cellulose/PDMS aerogel decrease, and consequently, its specific surface area is also lower. It can be observed in Fig. 4 b that the specific surface area of Cellulose/PDMS-30 is only 0.21 m²/g, a decrease of 97%. Therefore, it can be concluded that with the increase in vacuum loading time of PDMS into cellulose, there are fewer N₂ adsorption sites and a lower specific surface area, indicating that the porous structure in cellulose is gradually being tightly filled with PDMS, which is consistent with the aerogel structure depicted in Fig. 3 . Mechanical and piezoelectric properties of composite aerogels Figure 5 illustrates the compression strain curves of cellulose aerogels after PDMS filling and with varying PDMS contents. It is evident that with the increasing duration of PDMS loading, the compression resistance and compression modulus of the composite aerogels exhibit an upward trend. For the Cellulose sample without PDMS loading, the lowest compression stress of only 0.146 MPa is required to achieve 30% compression strain. Conversely, the pure PDMS sample also demonstrates poor compression resistance, needing only 0.121 MPa of compression stress to reach 30% compression strain. For the Cellulose/PDMS composite aerogels, the Cellulose/PDMS-5 requires a compression stress increase to 0.29 MPa to achieve 30% strain, with a 98% increase in compression modulus (compared to the original cellulose aerogel). When testing Cellulose/PDMS-20, a compression strain of 30% is achieved at 0.94 MPa, with a 543% increase in compression modulus. This fully demonstrates that loading PDMS materials with elastomeric properties into the three-dimensional porous structure of cellulose nanoarchitectures can effectively enhance the material's compression resistance, significantly improving the mechanical properties of its composite. However, when the PDMS vacuum loading time is extended to 30 minutes, the compression stress of Cellulose/PDMS-30 at 30% compression strain decreases to 0.7 MPa, indicating a certain degree of reduction in its compression resistance. This may be due to the excessive PDMS elastomer loaded internally affecting the overall aerogel architecture of cellulose and causing some damage to its composite structure, as evidenced by its extremely low specific surface area. Samples including Wood, Cellulose, PDMS, Cellulose/PDMS-5, Cellulose/PDMS-10, Cellulose/PDMS-20, and Cellulose/PDMS-30 were prepared into test devices with dimensions of 1.5 cm×1.5 cm×0.5 cm for piezoelectric response testing. Under an external force of approximately 30 N, the open-circuit voltage and short-circuit current of the materials were measured using an electrochemical workstation. As shown in Fig. 6 , untreated balsa wood exhibited extremely low piezoelectric response, with only 0.08 V open-circuit voltage and 0.7 nA short-circuit current detected. In contrast, the purified Cellulose sample demonstrated a significantly enhanced piezoelectric effect, with an open-circuit voltage of 1.0 V and a short-circuit current of 7 nA. This improvement is attributed to the porous structure of Cellulose, which provides high compressibility and greater strain under a constant external force. For the pure PDMS sample, the measured open-circuit voltage was 0.8 V. For the samples with PDMS loaded onto Cellulose, Cellulose/PDMS-5 exhibited an open-circuit voltage of 1.2 V and a short-circuit current of 10 nA, representing a 20% increase in open-circuit voltage and a 42% increase in short-circuit current compared to Cellulose alone. As the vacuum loading time of PDMS in the samples increased, Cellulose/PDMS-10 demonstrated an open-circuit voltage of 1.3 V and a short-circuit current of 15 nA, while Cellulose/PDMS-20 exhibited a piezoelectric response signal with an open-circuit voltage of 1.9 V and a short-circuit current of 26 nA, representing a 90% increase in open-circuit voltage and a 271% increase in short-circuit current compared to Cellulose. This enhancement is due to the close integration of the cellulose network with PDMS under a certain degree of PDMS filling, which facilitates internal charge conduction and improves the piezoelectric response capability under external force. Subsequently, the piezoelectric performance of Cellulose/PDMS-30 slightly decreased, possibly due to excessive PDMS filling disrupting the aerogel's pore structure, reducing the overall material's compressive modulus, and the hydrogen bonds between the two materials decreasing dipole displacement under compression, leading to a decline in the composite's piezoelectric properties. The alternating current generated (Fig. 7 b) by Cellulose/PDMS-20 could be rectified using a bridge rectifier to collect the electrical energy produced by Cellulose/PDMS-20. As illustrated in Fig. 7 a, to demonstrate the practical application of the Cellulose/PDMS-20 composite aerogel, we connected the current generated by Cellulose/PDMS-20 through a bridge rectifier to charge a 5 µF capacitor. The results showed that the prepared Cellulose/PDMS-20 could charge a 5 µF capacitor to 0.71 V within 120 seconds. This further confirms that Cellulose/PDMS-20 is capable of charging capacitors. As shown in the right panel of Fig. 7 c, the energy it generates can directly light up an LED lamp, demonstrating the broad application prospects of the natural balsa wood composites and expanding the applications of biomass materials in piezoelectricity. CONCLUSION In this study, we innovatively employed vacuum-loading technology to precisely and uniformly load PDMS into the structure of cellulose aerogel prepared from the purification of natural balsa wood, successfully developing a novel biomass-based piezoelectric composite material with unique properties. The components of this material exhibit excellent compatibility and are tightly integrated, forming a stable and efficient whole. Mechanical property test results indicate that the addition of PDMS significantly enhances the compressive strength of balsa wood cellulose aerogel. Under the same strain condition of 30%, compared with pure cellulose aerogel, the compressive stress of Cellulose/PDMS-20 shows an impressive increase of 543%. Compared with the unpurified balsa wood raw material, the purified cellulose aerogel performs exceptionally well in pressure response testing, with the open - circuit voltage soaring from 0.08V to 1.0V and the short - circuit current significantly increasing from 0.7nA to 7nA. During further in-depth research on PDMS vacuum loading, it was found that, compared with pure cellulose aerogel, the Cellulose/PDMS-20 material exhibits more outstanding piezoelectric performance, with the open-circuit voltage rising to 1.9V (a 90% increase) and the short-circuit current increasing to 26nA (a 271% increase). Based on the purification of pure natural cellulose raw materials and through the key approach of PDMS vacuum loading, we have successfully optimized the mechanical properties and piezoelectric response performance of balsa wood-based aerogels, paving a broader way for the large-scale application of bio-based materials in the fields of piezoelectric sensing and energy harvesting. Declarations Data availability No datasets were generated or analysed during the current study. Funding The work was supported by the Shenzhen Science and Technology Program (No. JCYJ20240813103608012), State Key Laboratory of New Textile Materials and Advanced Processing Technologies (No. FZ2024019), the Fundamental Research Funds for the Central Universities (WUT: 104972025RSCbs0190), the Postdoctoral Fellowship Program of CPSF (No. GZC20250081) and the China Postdoctoral Science Foundation (No. 2025M770109). Competing Interests The authors have no relevant financial or non-financial interests to disclose. 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Https://doi.org/doi: 10.1002/idm2.12033 Zheng Q, Zhang H, Mi H, Cai Z, Ma Z, Gong S (2016) High-performance flexible piezoelectric nanogenerators consisting of porous cellulose nanofibril (CNF)/poly(dimethylsiloxane) (PDMS) aerogel films. Nano Energy 26:504-512. Https://doi.org/10.1016/j.nanoen.2016.06.009 Additional Declarations No competing interests reported. Supplementary Files floatimage1.png Graphical Abstract Cite Share Download PDF Status: Posted Version 1 posted 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. We do this by developing innovative software and high quality services for the global research community. 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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-7320337","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":542639948,"identity":"df4d2d87-eaab-4239-af12-8b70bd254169","order_by":0,"name":"Yang Hu","email":"","orcid":"","institution":"Wuhan University of Technology","correspondingAuthor":false,"prefix":"","firstName":"Yang","middleName":"","lastName":"Hu","suffix":""},{"id":542639949,"identity":"f85d6560-9881-49cf-aaa4-8e6604ef426b","order_by":1,"name":"Quanling 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06:35:38","extension":"xml","order_by":19,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":83880,"visible":true,"origin":"","legend":"","description":"","filename":"fb1eb426254d4103a4f3fdfc50f2e77a1structuring.xml","url":"https://assets-eu.researchsquare.com/files/rs-7320337/v1/3c726f3e81321d4f4cd9d606.xml"},{"id":95790036,"identity":"c3f1e465-e8f5-428a-b15f-2958c3b021c1","added_by":"auto","created_at":"2025-11-13 06:35:38","extension":"html","order_by":20,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":91671,"visible":true,"origin":"","legend":"","description":"","filename":"earlyproof.html","url":"https://assets-eu.researchsquare.com/files/rs-7320337/v1/0fdd408f3e15ce3f02a90545.html"},{"id":95790009,"identity":"8ff88f37-d06b-40a8-984b-ac64850c169c","added_by":"auto","created_at":"2025-11-13 06:35:37","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":130314,"visible":true,"origin":"","legend":"\u003cp\u003eFourier transform infrared (FT-IR) spectra of Cellulose, PDMS, Cellulose/PDMS-5, Cellulose/PDMS-10, Cellulose/PDMS-20 and Cellulose/PDMS-30\u003c/p\u003e","description":"","filename":"floatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-7320337/v1/640f85f3c08cc00f65c9fbfb.png"},{"id":95801874,"identity":"cf045b44-74fa-459e-97fa-e1a2dc108e78","added_by":"auto","created_at":"2025-11-13 08:26:22","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":59985,"visible":true,"origin":"","legend":"\u003cp\u003eXRD patterns of Cellulose, PDMS, Cellulose/PDMS-5, Cellulose/PDMS-10, Cellulose/PDMS-20 and Cellulose/PDMS-30\u003c/p\u003e","description":"","filename":"floatimage3.png","url":"https://assets-eu.researchsquare.com/files/rs-7320337/v1/8b685494fcd369074f77a716.png"},{"id":95790013,"identity":"3c08abc0-d603-42df-ba32-6f09fbdf90b9","added_by":"auto","created_at":"2025-11-13 06:35:37","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":197682,"visible":true,"origin":"","legend":"\u003cp\u003eSEM images of cross-sections of (a, b) Cellulose, (c) Cellulose/PDMS-5, (d) Cellulose/PDMS-10, (f) Cellulose/PDMS-20 and (f) Cellulose/PDMS-30\u003c/p\u003e","description":"","filename":"floatimage4.png","url":"https://assets-eu.researchsquare.com/files/rs-7320337/v1/33329e9126f690cb1b4f0c28.png"},{"id":95802796,"identity":"f3849eb0-d9c4-435e-99ff-819e77c9d40b","added_by":"auto","created_at":"2025-11-13 08:28:32","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":123939,"visible":true,"origin":"","legend":"\u003cp\u003e(a) Nitrogen adsorption/desorption isotherms and (b) Barrett-Joyner-Halenda (BJH) pore size distribution of Cellulose/PDMS aerogels\u003c/p\u003e","description":"","filename":"floatimage5.png","url":"https://assets-eu.researchsquare.com/files/rs-7320337/v1/ca4eac4bbe76f9be2255b42a.png"},{"id":95802774,"identity":"484ff04b-184e-49ff-9348-8b13e5045639","added_by":"auto","created_at":"2025-11-13 08:28:27","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":130659,"visible":true,"origin":"","legend":"\u003cp\u003eThe compression strain curves of Cellulose, PDMS, Cellulose/PDMS-5, Cellulose/PDMS-10, Cellulose/PDMS-20, and Cellulose/PDMS-30\u003c/p\u003e","description":"","filename":"floatimage6.png","url":"https://assets-eu.researchsquare.com/files/rs-7320337/v1/42ca8b74b92f9b9f10c63685.png"},{"id":95790019,"identity":"60339f8d-b959-4d14-95c2-5ea0d1f77527","added_by":"auto","created_at":"2025-11-13 06:35:37","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":212063,"visible":true,"origin":"","legend":"\u003cp\u003e(a) Open-circuit voltage and (b) short-circuit current of Wood, Cellulose, PDMS, Cellulose/PDMS-5, Cellulose/PDMS-10, Cellulose/PDMS-20, and Cellulose/PDMS-30.\u003c/p\u003e","description":"","filename":"floatimage7.png","url":"https://assets-eu.researchsquare.com/files/rs-7320337/v1/67122799fa4248acc2636892.png"},{"id":95802101,"identity":"d9ca8a41-9245-4b7f-96bd-b1ed9e56e9a1","added_by":"auto","created_at":"2025-11-13 08:26:51","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":148697,"visible":true,"origin":"","legend":"\u003cp\u003e(a) Capacitor charging diagram, (b) Schematic diagram of bridge rectifier structure, (c) Image of lighting up an LED lamp.\u003c/p\u003e","description":"","filename":"floatimage8.png","url":"https://assets-eu.researchsquare.com/files/rs-7320337/v1/e6f8785c6371d4a7df840b4a.png"},{"id":96710108,"identity":"506da00d-39b7-4d86-a0b0-fdea016d62ff","added_by":"auto","created_at":"2025-11-25 10:10:04","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1459327,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7320337/v1/99409328-3cbc-40ce-8dd8-c7b5c1e803d7.pdf"},{"id":95790011,"identity":"1faa1192-ad3a-4e8c-bf3c-0c3fabc7dd40","added_by":"auto","created_at":"2025-11-13 06:35:37","extension":"png","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":474075,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eGraphical Abstract\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"floatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-7320337/v1/7bc4f1a3ed1075e45b1d31e9.png"}],"financialInterests":"No competing interests reported.","formattedTitle":"Mechanically Durable Balsa Wood-PDMS Composites for Self-Powered Vibration Energy Harvesting","fulltext":[{"header":"Introduction","content":"\u003cp\u003eDue to the shortage of fossil energy resources and environmental concerns, there is an increasing demand for alternative renewable energy sources (Lior \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2010\u003c/span\u003e; Zhang et al. \u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e2023\u003c/span\u003e; Mo et al. \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e2022\u003c/span\u003e.). Mechanical energy, as a renewable and sustainable resource, is widely distributed in the environment and exists in various forms such as human motion, vibration, wind, and sound. However, a significant portion of mechanical energy remains untapped. In recent years, diverse methods have been developed to directly harness mechanical energy or convert it into other forms (Lin et al. \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e2013\u003c/span\u003e; Zheng et al. \u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). Nanogenerators (NGs), capable of harvesting energy from environmental sources including mechanical vibrations (Qin et al. \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e2008\u003c/span\u003e), heat (Hu et al. \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2010\u003c/span\u003e; Lee et al. \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e2014\u003c/span\u003e), sound waves (Lee et al. \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e2013\u003c/span\u003e), and human activities (Lee et al. \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e2012\u003c/span\u003e), have garnered considerable attention from researchers. Since 2006, NGs based on ZnO nanowires, which can convert mechanical energy into electrical energy, have been extensively studied (Qin et al. \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e2008\u003c/span\u003e). The development of ZnO nanowire-based NGs has achieved output power levels in the sub-milliwatt range, sufficient to power numerous small-scale electronic devices such as commercial light-emitting diodes (Yang et al. \u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e2012\u003c/span\u003e), various sensors (Lin et al. \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e2013\u003c/span\u003e), and liquid crystal displays (Hu et al. \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2010\u003c/span\u003e). Nevertheless, such NGs typically require complex fabrication and manufacturing processes, thereby limiting their mechanical flexibility and potential applications.\u003c/p\u003e\u003cp\u003eBiomass-based piezoelectric materials, as a novel category of piezoelectric materials, have been investigated by researchers (Xu et al. \u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e2025\u003c/span\u003e) due to their environmentally friendly nature, biodegradability, biocompatibility, and abundant availability. As piezoelectric materials, cellulose-based materials have emerged as a research hotspot (Trellu et al. \u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e2023\u003c/span\u003e) owing to their unique mechanical properties, ease of processing and preparation, and favorable piezoelectric performance. Currently, cellulose-based piezoelectric materials are developing rapidly, and several achievements have been made in the field of piezoelectric materials based on cellulose.\u003c/p\u003e\u003cp\u003eCellulose, with its abundant reserves primarily found in plant cell walls, is widely available and inexpensive. It also exhibits both direct and converse piezoelectric effects (Chen et al. \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2024\u003c/span\u003e). The fundamental chemical structure unit of cellulose mainly consists of glucose molecules linked by glycosidic bonds (Abe et al. 2011; Isogai et al. \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e2011\u003c/span\u003e). In addition to cellulose, which constitutes a significant portion of natural plants, lignin and hemicellulose are also present (Bertolo et al. \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2025\u003c/span\u003e). These components play roles in supporting plant growth and providing mechanical strength, but they lack favorable flexibility and piezoelectric properties. By removing lignin and hemicellulose, high-performance cellulose can be obtained (Tezcan et al. 2017). Therefore, cellulose can be extracted from natural plants by removing lignin and hemicellulose. Freeze-drying technology is commonly employed for the preparation of cellulose aerogels (Yahya et al. \u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e2015\u003c/span\u003e; Rahmanian et al. \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e2021\u003c/span\u003e Shi et al. \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e2018\u003c/span\u003e). Through composite material technology, which involves combining cellulose with other materials, piezoelectric materials with excellent performance can be achieved. Cellulose aerogels and their composites boast unique advantages such as biodegradability, biocompatibility, and excellent mechanical properties, making them highly suitable for material selection in flexible piezoelectric sensor devices. Cellulose exhibits intrinsic piezoelectric properties, and its distinctive nanoscale porous structure can generate pore electrets with piezoelectric responses, endowing it with broad application prospects in flexible piezoelectric sensor devices (Li et al. 2018; Zheng et al. \u003cspan citationid=\"CR53\" class=\"CitationRef\"\u003e2016\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eTo further enhance the compressive resistance of the overall piezoelectric sensor device and improve the charge conduction capability of the responsive charges within the aerogel network, polymers with superior mechanical properties can be introduced for compounding. Polydimethylsiloxane (PDMS) is a silicon-containing polymer material that possesses excellent corrosion resistance, thermal stability, unique flexibility, and mechanical properties. Hu et al. (Hu et al. 2011) utilized the good piezoelectric properties of PDMS to compound it with lead zirconate titanate (PZT) nanowires, resulting in a composite film with favorable piezoelectric characteristics. The transmittance of the piezoelectric composite film prepared via dielectrophoresis technology reached 72%, a significant improvement compared to the 42% transmittance of non-oriented piezoelectric films. The piezoelectric nanogenerator based on the uniformly oriented PZT nanowire/PDMS composite was capable of outputting a voltage of 0.60 V and a current of 3.95 nA, representing increases of 88% and 62%, respectively, compared to the non-oriented piezoelectric film. Additionally, they has successfully applied this composite in the field of smartphone privacy screens, achieving favorable results.\u003c/p\u003e\u003cp\u003eIn this study, we utilized balsa wood as the source of cellulose and introduced PDMS to enhance the mechanical properties of the aerogel, successfully developing a piezoelectric nanogenerator with high mechanical strength. The specific procedures were as follows: First, the natural balsa wood raw material was purified. Subsequently, the substances within it were replaced with tert-butyl alcohol, and then a freeze-drying process was employed to obtain cellulose aerogel with a high specific surface area. Next, the cellulose aerogel was immersed in a PDMS solution, and through vacuum infiltration technology, PDMS was fully filled into the pores of the balsa wood cellulose aerogel, resulting in the preparation of cellulose/PDMS aerogel. The experimental results revealed that the Cellulose/PDMS-20 aerogel sample prepared under a 20-minute PDMS negative pressure loading condition exhibited excellent compressive modulus and optimal triboelectric output performance (with an output voltage as high as 1.9V and a short-circuit current of 26nA). This performance was significantly superior to the 1.65V output voltage of the cellulose acetate/cellulose nanocrystal composite nanofiber membrane (Sun et al. \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e2022\u003c/span\u003e) and was comparable to the 2.0V output voltage of cotton nanofibers (Wang et al. \u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). It is noteworthy that in this study, after purifying natural cellulose raw materials, we directly incorporated the elastomer PDMS for mechanical reinforcement and utilized the composite as a piezoelectric material, without the need to modify the natural cellulose. Moreover, this method can further enhance the overall piezoelectric response capability of the device by introducing piezoelectric ceramics, thereby expanding the application scope of bio-based materials in the piezoelectric field. It holds significant theoretical and practical implications for the development of environmentally friendly and sustainable green energy technologies.\u003c/p\u003e"},{"header":"Experimental","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\u003ch2\u003eMaterials\u003c/h2\u003e\u003cp\u003eNatural Balsa Wood was provided by Nippon Paper Industries (Tokyo, Japan). NaClO\u003csub\u003e2\u003c/sub\u003e was bought from Aladdin (Shanghai, China). PDMS prepolymer and crosslinking agent were purchased from Dow chemistry (China). Acetic acid, ethanol and tert-butanol were purchased from Taicang Hushi Co., Ltd. (China). Sodium hydroxide and other pharmaceutical reagents were purchased from Aladdin (China).\u003c/p\u003e\u003c/div\u003e\n\u003ch3\u003eThe purification process of balsa wood\u003c/h3\u003e\n\u003cp\u003eLignin in balsa wood was oxidized using a sodium chlorite and acetic acid aqueous system to obtain lignin-free balsa wood. Specifically, 5 g of balsa wood cubes (2 cm \u0026times; 2 cm \u0026times; 2 cm) were accurately weighed and added to a 300 ml conical flask. Then, 160 ml of water was accurately measured and added to the flask, followed by the addition of 0.5 ml of acetic acid using a plastic dropper. The flask containing the sample was placed in a 75 ℃ water bath for heating. After a certain period, 1.5 g of NaClO₂ was added to the flask, which was then covered with a smaller conical flask of appropriate diameter. The flask was shaken every five minutes to ensure a thorough reaction. After one hour of reaction, an additional 0.5 ml of CH₃COOH was added using a plastic dropper, followed by the addition of another 1.5 g of NaClO₂. The reaction was allowed to proceed for 1 h in the flask, with shaking every five minutes to ensure complete reaction. This process was repeated four times. Subsequently, the mixture was cooled in an ice-water bath, and after a period, suction filtration was performed. The residue was washed approximately five times with deionized water to obtain lignin-free balsa wood.\u003c/p\u003e\u003cp\u003eHemicellulose in balsa wood was removed using a concentrated sodium hydroxide (NaOH) solution. Specifically, 30 ml of 17.5% NaOH solution and 150 ml of 9.5% NaOH solution were accurately weighed and prepared. The lignin-free balsa wood prepared in the previous stage was placed in a beaker. Initially, 30 ml of 17.5% NaOH solution was added (in portions, with magnetic stirring for 2\u0026ndash;3 minutes between additions), and the beaker was allowed to mercerize at room temperature for 45 minutes. Subsequently, 30 ml of water was added to the beaker, followed by magnetic stirring for 2 minutes. The mixture was then filtered using a Buchner funnel. The resulting solid was washed three times with 50 ml of 9.5% NaOH solution and subsequently with deionized water until neutrality was achieved, yielding balsa wood cellulose.\u003c/p\u003e\n\u003ch3\u003ePreparation of Cellulose Aerogel and PDMS/Cellulose Composite Aerogel\u003c/h3\u003e\n\u003cp\u003eThe preparation of cellulose aerogel and PDMS/cellulose composite aerogel is described as follows. The balsa wood cellulose obtained previously was subjected to ethanol replacement to remove water. Initially, a 10% ethanol-water solution was prepared, and the balsa wood was placed in this solution and shaken on a rocker to ensure thorough replacement. After one hour, the ethanol concentration was sequentially increased to 30%, 50%, 70%, and 90%, with each replacement step lasting one hour. Finally, the balsa wood cellulose was placed in pure ethanol overnight. Subsequently, tert-butanol was used to replace the ethanol solvent. The ethanol was replaced with tert-butanol in a stepwise manner (10%, 30%, 50%, 70%, 90%, and finally pure tert-butanol), with each replacement step lasting one hour on a rocker until the balsa wood cellulose was left in pure tert-butanol overnight. After the replacement process, the material was placed in a refrigerator for freezing and subsequently freeze-dried at -45\u0026deg;C for two days to obtain the cellulose aerogel (Zhang et al. \u003cspan citationid=\"CR49\" class=\"CitationRef\"\u003e2025\u003c/span\u003e), denoted as \"Cellulose\u0026rdquo;. The natural balsa wood was denoted as \"Wood\". To prepare the PDMS/cellulose composite aerogel, a PDMS mixture was prepared at room temperature using PDMS prepolymer and PDMS curing agent (uncured or slowly curing at room temperature). The balsa wood cellulose aerogel was placed in the PDMS solution, and PDMS was infiltrated into the pores of the cellulose aerogel using vacuum. This process was repeated 3\u0026ndash;5 times. The infiltrated aerogel was then placed in an oven for curing, followed by demolding to obtain the PDMS/cellulose composite aerogel. By controlling the duration of PDMS infiltration under vacuum, PDMS/cellulose aerogels with varying PDMS contents were prepared. The aerogels infiltrated with PDMS for 5, 10, 20, and 30 minutes under vacuum were denoted as Cellulose/PDMS-5, Cellulose/PDMS-10, Cellulose/PDMS-20, and Cellulose/PDMS-30, respectively.\u003c/p\u003e\n\u003ch3\u003eCharacterization\u003c/h3\u003e\n\u003cp\u003eThe prepared samples of cellulose, PDMS, cellulose/PDMS-5, cellulose/PDMS-10, cellulose/PDMS-20 and cellulose/PDMS-30 were tested using a Fourier Transform Infrared (FTIR) spectrometer from Nicolet Corporation (USA). The test samples were 1 cm \u0026times; 1 cm thin films, and measurements were conducted in transmission mode (in the near-infrared region).\u003c/p\u003e\u003cp\u003eTests were carried out using an X-ray diffractometer from Rigaku Corporation (Japan). The sample dimensions (length \u0026times; width) of cellulose, PDMS, cellulose/PDMS-5, cellulose/PDMS-10, cellulose/PDMS-20 and cellulose/PDMS-30 were less than 1 cm, and their height was less than 0.5 cm. Measurements were performed in reflection mode with a scanning range of 2θ\u0026thinsp;=\u0026thinsp;5\u0026deg; \u0026minus;\u0026thinsp;75\u0026deg;.\u003c/p\u003e\u003cp\u003eTesting was conducted using a Scanning Electron Microscope (SEM, Hitachi S-4800) from a Japanese company. Cross-sectional images of cellulose, cellulose/PDMS-5, cellulose/PDMS-10, cellulose/PDMS-20 and cellulose/PDMS-30 were captured and scanned.\u003c/p\u003e\u003cp\u003eThe open-circuit voltage (V) and short-circuit current (A) of wood, cellulose, PDMS, cellulose/PDMS-5, cellulose/PDMS-10, cellulose/PDMS-20 and cellulose/PDMS-30 were measured using a CHI-660E electrochemical workstation from Shanghai Chenhua Instrument Co., Ltd.\u003c/p\u003e\u003cp\u003eInstruments from MTS Systems Corporation were used to test the samples. Cellulose, PDMS, cellulose/PDMS-5, cellulose/PDMS-10, cellulose/PDMS-20 and cellulose/PDMS-30 were cut into 20 mm \u0026times; 10 mm strips and placed in a universal testing machine. The initial compression rate was set at 1 mm/min for compression testing (conducted at room temperature and 50% humidity).\u003c/p\u003e\u003cp\u003eThe specific surface area of cellulose, cellulose/PDMS-5, cellulose/PDMS-10, cellulose/PDMS-20 and cellulose/PDMS-30 was analyzed in powder form using an ASAP 2460 automatic specific surface area and porosity analyzer from Micromeritics Instrument Corporation (USA).\u003c/p\u003e\u003cp\u003eCellulose/PDMS-5 and cellulose/PDMS-30 were analyzed using an ESCALAB 250Xi X-ray Photoelectron Spectrometer (XPS) from Thermo Fisher Scientific (USA).\u003c/p\u003e"},{"header":"Results and Discussion","content":"\u003cdiv id=\"Sec8\" class=\"Section2\"\u003e\u003ch2\u003eThe Structures of Cellulose/PDMS composite aerogels\u003c/h2\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e illustrates the FTIR spectra of Cellulose, PDMS, Cellulose/PDMS-5, Cellulose/PDMS-10, Cellulose/PDMS-20, and Cellulose/PDMS-30 within the range of 4000\u0026ndash;500 cm⁻\u0026sup1;. It can be observed that Cellulose exhibits characteristic peaks at 3343 cm⁻\u0026sup1;, 2910 cm⁻\u0026sup1;, and 1058 cm⁻\u0026sup1;, corresponding to the stretching vibrations of O-H, C\u0026ndash;H, and C\u0026ndash;O bonds in the cellulose molecular structure, respectively. These principal characteristic peaks remain largely unchanged with the vacuum loading of PDMS. Conversely, PDMS displays characteristic peaks at 2962 cm⁻\u0026sup1;, 1000\u0026ndash;1100 cm⁻\u0026sup1;, and 790 cm⁻\u0026sup1;, corresponding to the stretching vibrations of C-H, Si-O, and Si-C bonds, respectively. In the FTIR spectra of Cellulose/PDMS-5, Cellulose/PDMS-10, Cellulose/PDMS-20, and Cellulose/PDMS-30, characteristic peaks from both materials can be simultaneously observed, indicating a relatively stable composite formation between the two materials. However, it is notable that in the Cellulose/PDMS-30 composite, as the duration of vacuum loading with PDMS increases (i.e., as PDMS content rises), the intensity of the O-H characteristic peak of cellulose slightly diminishes, possibly due to hydrogen bonding between PDMS and cellulose (Trellu et al. \u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e2023\u003c/span\u003e).\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e displays the X-ray diffraction (XRD) patterns of cellulose, PDMS, cellulose/PDMS-5, cellulose/PDMS-10, cellulose/PDMS-20, and cellulose/PDMS-30 within the 2θ range of 5\u0026deg; to 75\u0026deg;. Most of the cellulose within the composite aerogels exhibits a Type II crystalline structure. In the XRD pattern of the cellulose aerogel, a distinct diffraction peak is observed at 2θ\u0026thinsp;=\u0026thinsp;12.5\u0026deg;, corresponding to the (1\u0026ndash;10) plane of cellulose II crystals. Additionally, a prominent diffraction peak is detected near 2θ\u0026thinsp;\u0026asymp;\u0026thinsp;21\u0026deg;, representing a broadened peak associated with the (110) and (020) planes of cellulose II crystals (Shi et al., \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e2014\u003c/span\u003e). In comparison, cellulose is a polymeric material with relatively high crystallinity, while PDMS exhibits low crystallinity, displaying only a broad and low-intensity diffraction peak near 2θ\u0026thinsp;\u0026asymp;\u0026thinsp;21\u0026deg;, which is relatively close in position to the characteristic peak of cellulose. Therefore, when PDMS is introduced into the cellulose aerogel, the XRD pattern of the resulting composite primarily features the crystalline characteristic peaks of cellulose, indicating that PDMS has been thoroughly dispersed and embedded within the cellulose aerogel matrix of the composite. Furthermore, as the vacuum filling time of PDMS increases, the characteristic peaks in the XRD pattern remain largely unchanged, suggesting that the crystalline state of the cellulose aerogel remains unaltered.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e presents cross-sectional images of Cellulose, Cellulose/PDMS-5, Cellulose/PDMS-10, Cellulose/PDMS-20, and Cellulose/PDMS-30. In Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ea-b, the highly porous structure within the cellulose aerogel material is observable, alongside its layered architecture (which is delimited by cell walls into stratified layers). The layered, porous cellulose aerogel, segmented by cell walls, also imparts compressibility to the material. As PDMS is introduced in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ec-f, the porous structure within the cellulose aerogel gradually becomes filled, with the SEM images clearly demonstrating the densification of the material's porous framework by PDMS. The porous structures of Cellulose, Cellulose/PDMS-5, Cellulose/PDMS-10, Cellulose/PDMS-20, and Cellulose/PDMS-30 reveal a progressive reduction in porosity of the composite aerogels as the PDMS soaking/loading duration increases. Despite PDMS infiltration, the material retains its intact layered structure, as evidenced by the discernible cell walls in the SEM images, indicating a robust integration of the two components to form a structurally cohesive composite aerogel material.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eAs depicted in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ea, the Cellulose aerogel without PDMS loading possesses the highest nitrogen adsorption sites. Correspondingly, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eb, the Cellulose aerogel without PDMS loading exhibits the highest specific surface area, reaching up to 7.1 m\u0026sup2;/g. Meanwhile, Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ea illustrates that with the increase in PDMS loading time, the nitrogen adsorption sites of the composite Cellulose/PDMS aerogel decrease, and consequently, its specific surface area is also lower. It can be observed in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eb that the specific surface area of Cellulose/PDMS-30 is only 0.21 m\u0026sup2;/g, a decrease of 97%. Therefore, it can be concluded that with the increase in vacuum loading time of PDMS into cellulose, there are fewer N₂ adsorption sites and a lower specific surface area, indicating that the porous structure in cellulose is gradually being tightly filled with PDMS, which is consistent with the aerogel structure depicted in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e.\u003c/p\u003e\u003c/div\u003e\n\u003ch3\u003eMechanical and piezoelectric properties of composite aerogels\u003c/h3\u003e\n\u003cp\u003e\u003c/p\u003e\u003cp\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e illustrates the compression strain curves of cellulose aerogels after PDMS filling and with varying PDMS contents. It is evident that with the increasing duration of PDMS loading, the compression resistance and compression modulus of the composite aerogels exhibit an upward trend. For the Cellulose sample without PDMS loading, the lowest compression stress of only 0.146 MPa is required to achieve 30% compression strain. Conversely, the pure PDMS sample also demonstrates poor compression resistance, needing only 0.121 MPa of compression stress to reach 30% compression strain. For the Cellulose/PDMS composite aerogels, the Cellulose/PDMS-5 requires a compression stress increase to 0.29 MPa to achieve 30% strain, with a 98% increase in compression modulus (compared to the original cellulose aerogel). When testing Cellulose/PDMS-20, a compression strain of 30% is achieved at 0.94 MPa, with a 543% increase in compression modulus. This fully demonstrates that loading PDMS materials with elastomeric properties into the three-dimensional porous structure of cellulose nanoarchitectures can effectively enhance the material's compression resistance, significantly improving the mechanical properties of its composite. However, when the PDMS vacuum loading time is extended to 30 minutes, the compression stress of Cellulose/PDMS-30 at 30% compression strain decreases to 0.7 MPa, indicating a certain degree of reduction in its compression resistance. This may be due to the excessive PDMS elastomer loaded internally affecting the overall aerogel architecture of cellulose and causing some damage to its composite structure, as evidenced by its extremely low specific surface area.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eSamples including Wood, Cellulose, PDMS, Cellulose/PDMS-5, Cellulose/PDMS-10, Cellulose/PDMS-20, and Cellulose/PDMS-30 were prepared into test devices with dimensions of 1.5 cm\u0026times;1.5 cm\u0026times;0.5 cm for piezoelectric response testing. Under an external force of approximately 30 N, the open-circuit voltage and short-circuit current of the materials were measured using an electrochemical workstation. As shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e, untreated balsa wood exhibited extremely low piezoelectric response, with only 0.08 V open-circuit voltage and 0.7 nA short-circuit current detected. In contrast, the purified Cellulose sample demonstrated a significantly enhanced piezoelectric effect, with an open-circuit voltage of 1.0 V and a short-circuit current of 7 nA. This improvement is attributed to the porous structure of Cellulose, which provides high compressibility and greater strain under a constant external force. For the pure PDMS sample, the measured open-circuit voltage was 0.8 V. For the samples with PDMS loaded onto Cellulose, Cellulose/PDMS-5 exhibited an open-circuit voltage of 1.2 V and a short-circuit current of 10 nA, representing a 20% increase in open-circuit voltage and a 42% increase in short-circuit current compared to Cellulose alone. As the vacuum loading time of PDMS in the samples increased, Cellulose/PDMS-10 demonstrated an open-circuit voltage of 1.3 V and a short-circuit current of 15 nA, while Cellulose/PDMS-20 exhibited a piezoelectric response signal with an open-circuit voltage of 1.9 V and a short-circuit current of 26 nA, representing a 90% increase in open-circuit voltage and a 271% increase in short-circuit current compared to Cellulose. This enhancement is due to the close integration of the cellulose network with PDMS under a certain degree of PDMS filling, which facilitates internal charge conduction and improves the piezoelectric response capability under external force. Subsequently, the piezoelectric performance of Cellulose/PDMS-30 slightly decreased, possibly due to excessive PDMS filling disrupting the aerogel's pore structure, reducing the overall material's compressive modulus, and the hydrogen bonds between the two materials decreasing dipole displacement under compression, leading to a decline in the composite's piezoelectric properties.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eThe alternating current generated (Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003eb) by Cellulose/PDMS-20 could be rectified using a bridge rectifier to collect the electrical energy produced by Cellulose/PDMS-20. As illustrated in Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003ea, to demonstrate the practical application of the Cellulose/PDMS-20 composite aerogel, we connected the current generated by Cellulose/PDMS-20 through a bridge rectifier to charge a 5 \u0026micro;F capacitor. The results showed that the prepared Cellulose/PDMS-20 could charge a 5 \u0026micro;F capacitor to 0.71 V within 120 seconds. This further confirms that Cellulose/PDMS-20 is capable of charging capacitors. As shown in the right panel of Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003ec, the energy it generates can directly light up an LED lamp, demonstrating the broad application prospects of the natural balsa wood composites and expanding the applications of biomass materials in piezoelectricity.\u003c/p\u003e"},{"header":"CONCLUSION","content":"\u003cp\u003eIn this study, we innovatively employed vacuum-loading technology to precisely and uniformly load PDMS into the structure of cellulose aerogel prepared from the purification of natural balsa wood, successfully developing a novel biomass-based piezoelectric composite material with unique properties. The components of this material exhibit excellent compatibility and are tightly integrated, forming a stable and efficient whole. Mechanical property test results indicate that the addition of PDMS significantly enhances the compressive strength of balsa wood cellulose aerogel. Under the same strain condition of 30%, compared with pure cellulose aerogel, the compressive stress of Cellulose/PDMS-20 shows an impressive increase of 543%. Compared with the unpurified balsa wood raw material, the purified cellulose aerogel performs exceptionally well in pressure response testing, with the open - circuit voltage soaring from 0.08V to 1.0V and the short - circuit current significantly increasing from 0.7nA to 7nA. During further in-depth research on PDMS vacuum loading, it was found that, compared with pure cellulose aerogel, the Cellulose/PDMS-20 material exhibits more outstanding piezoelectric performance, with the open-circuit voltage rising to 1.9V (a 90% increase) and the short-circuit current increasing to 26nA (a 271% increase). Based on the purification of pure natural cellulose raw materials and through the key approach of PDMS vacuum loading, we have successfully optimized the mechanical properties and piezoelectric response performance of balsa wood-based aerogels, paving a broader way for the large-scale application of bio-based materials in the fields of piezoelectric sensing and energy harvesting.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cem\u003eData availability\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eNo datasets were generated or analysed during the current study.\u003c/p\u003e\u003cp\u003e\u003cem\u003eFunding\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eThe work was supported by the Shenzhen Science and Technology Program (No. JCYJ20240813103608012), State Key Laboratory of New Textile Materials and Advanced Processing Technologies (No. FZ2024019), the Fundamental Research Funds for the Central Universities (WUT: 104972025RSCbs0190), the Postdoctoral Fellowship Program of CPSF (No. GZC20250081) and the China Postdoctoral Science Foundation (No. 2025M770109).\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003cem\u003eCompeting Interests\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eThe authors have no relevant financial or non-financial interests to disclose.\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003cem\u003eEthics approval\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003cem\u003eConsent for publication\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eAll the authors agreed to publish this manuscript in this journal.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eAbe K, Yano H (2011) Formation of hydrogels from cellulose nanofibers. 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Https://doi.org/10.1016/j.nanoen.2016.06.009\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Balsa wood, PDMS, Piezoelectric sensor","lastPublishedDoi":"10.21203/rs.3.rs-7320337/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7320337/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eWith the continuous advancement of social technology, fossil fuel shortages and environmental pollution are becoming increasingly severe, leading to growing attention toward renewable energy technologies. Consequently, the development of novel eco-friendly energy devices holds significant importance. As a type of innovative eco-friendly energy device, piezoelectric materials have garnered extensive scholarly interest due to their ability to harvest energy from the environment (such as mechanical vibrations, sound waves, and human activities). Herein, we selects natural balsa wood as the substrate material in this study. After undergoing purification treatment to remove non-cellulosic impurities, the cellulose within the balsa wood retains an aerogel structure characterized by a high specific surface area and porosity. Furthermore, The cellulose/PDMS-20 aerogel samples, prepared under the condition of PDMS negative-pressure loading for 20 minutes, exhibit excellent compressive modulus and optimal triboelectric output performance, with an output voltage as high as 1.9 V and a short-circuit current of 26 nA, demonstrating promising application prospects in the field of wearable self-powered sensing.\u003c/p\u003e","manuscriptTitle":"Mechanically Durable Balsa Wood-PDMS Composites for Self-Powered Vibration Energy Harvesting","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-11-13 06:35:33","doi":"10.21203/rs.3.rs-7320337/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"d50f09fe-9114-49be-9cf4-ac4c8e3b3df7","owner":[],"postedDate":"November 13th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2025-11-24T19:53:25+00:00","versionOfRecord":[],"versionCreatedAt":"2025-11-13 06:35:33","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7320337","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7320337","identity":"rs-7320337","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}