3D层状木基微压传感器的制备及性能

Preparation and Properties of 3D Layered Wood-Based Micro-Pressure Sensor

【目的】将去除木质素、半纤维素组分的木材作为传感器骨架材料,研究其与导电聚合物的含固比对压力传感器感测性能的影响,为开发基于绿色天然材料的低成本、高性能传感器提供新思路。【方法】以轻木为原料,通过NaClO2、NaOH溶液两步法选择性地从细胞壁中去除木质素和半纤维素组分,应用冷冻干燥技术制备木基气凝胶并将其作为传感器骨架材料;采用浸渍法将气凝胶骨架浸入导电聚合物聚(3,4-乙烯二氧基噻吩)-聚(苯乙烯磺酸盐)(PEDOT∶PSS)和偶联剂3-缩水甘油基氧基丙基三甲氧基硅烷(GOPS)混合溶液中,经冷冻干燥后低温加热使三者交联,制备3D层状木基微压传感器;对3D层状木基微压传感器进行结构形态表征和电学、感测性能测试,探讨木基气凝胶骨架与PEDOT∶PSS含固比对压力传感器感测性能的影响。【结果】木基气凝胶骨架结构机械可压缩性好、高度多孔、具有特殊分层结构,有利于PEDOT∶PSS和GOPS混合溶液吸附,CPG-0.25、CPG-0.5、CPG-0.75的电导率分别为0.02、0.15和3.04 mS·cm^(-1),最大压缩应变分别为72%、62%和51%,微压灵敏度分别为95.93(R^(2)=99.6%)、96.88(R^(2)=99.8%)和108.34 kPa-1(R^(2)=99.1%),随着PEDOT∶PSS含固比增大,复合导电气凝胶的电导率不断增大,传感器最大压缩应变逐渐减小,传感器在微压(1.5 kPa)下灵敏度逐渐增大,压力传感器CPG-0.75的微压灵敏度最高,且显示出良好的线性度和优异的稳定性(2 kPa下5 000个加载-卸载循环试验的相对电阻变化率稳定,无明显电信号波动)。【结论】木基气凝胶与PEDOT∶PSS含固比对3D层状木基微压传感器的微压灵敏度影响较大,随着PEDOT∶PSS含固比增大,复合导电气凝胶的导电性增强,传感器微压灵敏度提高。3D拱形层状多孔木基气凝胶骨架一方面在微小压力作用下传感器能够产生更多接触,电阻变化率较大,使传感器具有优异的微压灵敏度;另一方面骨架结构机械可压缩性好,使传感器具有良好的稳定性。

【Objective】The wood from which lignin and hemicellulose were removed was used as the sensor skeleton, and the effect of the solid content weight ratio of the wood and conductive polymer on the performance of the pressure sensor was studied in order to develop low-cost and high-performance sensor devices based on green natural materials.【Method】Using balsa wood as raw material, lignin and hemicellulose components were selectively removed from cell wall by two-step method, and wood-based aerogel was prepared by freeze-drying as sensor skeleton. The aerogel skeleton was dipped into the mixed solution of conductive polymer poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate)(PEDOT∶PSS) and couling agent 3-glycidoxypropyltrimethoxysilane solution(GOPS) by dipping method, and the low temperature heating after freeze drying made the three crosslink, so that the 3D layered wood-based micro-pressure sensor was prepared. The structure and morphology of the sensor were characterized, and the electrical and sensing properties were tested. The influence of the solid content weight ratio of wood-based aerogel skeleton to PEDOT∶PSS on the sensing performance of the pressure sensor was discussed.【Result】The wood-based aerogel has good mechanical compressibility, high porosity and special layered structure, which is beneficial to the adsorption of mixed solution of PEDOT∶PSS and GOPS. The conductivity of CPG-0.25, CPG-0.5 and CPG-0.75 are 0.02, 0.15 and 3.04 mS·cm^(-1), respectively. The maximum compressive strain is 72%, 62% and 51% respectively. The micro-pressure sensitivity is 95.93(R^(2)=99.6%), 96.88(R^(2)=99.8%) and 108.34 kPa-1(R^(2)=99.1%), respectively. The results show that with the increase of the solid content ratio of PEDOT∶PSS, the conductivity of the composite conductive aerogel increases continuously, the maximum compressive strain of the sensor decreases, and the sensitivity of the sensor under micro-pressure(1.5 kPa) increases gradually. The micro-pressure sensitivity of the pressure sensor CPG-0.75 is the highest, and it shows good linearity and excellent stability(the relative resistance of 5 000 loading-unloading cycles under 2 kPa changes stably, with no obvious fluctuation).【Conclusion】The solid ratio of wood-based aerogel to PEDOT∶PSS has great influence on the micro-pressure sensitivity of the pressure sensor. With the increase of the solid content weight ratio of PEDOT∶PSS, the conductivity of the composite conductive aerogel is enhanced, and the micro-pressure sensitivity of the sensor is improved. On the one hand, the 3D arched layered porous wood-based aerogel skeleton enables the sensor to generate more contact under the action of slight pressure, thus resulting in a larger resistance change rate, which makes the sensor have excellent micro-pressure sensitivity. On the other hand, this skeleton structure has good mechanical compressibility, which makes the sensor have good stability.