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

【 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 (R2 = 99. 6%), 96. 88 (R2 = 99. 8%) and 108. 34 kPa-1(R2 = 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. © 2022 Chinese Society of Forestry. All rights reserved.