Research On A Flexible Pressure Sensor Based On Wood Aerogel

As an important part of smart wearables,flexible pressure sensors play an important role in human health monitoring,motion detection,human-computer interaction,and electronic skin.Scientists have developed various flexible pressure sensors with excellent performance based on different new structures and new materials.However,there are still a great challenge in preparing flexible pressure sensors with ultra-compressibility,high sensitivity,wide detection limit and low hysteresis.Flexible three-dimensional conductive materials are of great significance to the preparation of sensors with excellent performance,with excellent compressibility and conductivity.In this paper,natural Balsa wood was prepared into wood aerogel(WA)by simple chemical treatment and freeze-drying.The FTIR spectrum shows that lignin and hemicellulose have been removed.It can be seen from the SEM image that WA has a multi-layer arch structure to increase its compression performance.This paper reports two methods for imparting conductivity to wood aerogels,and assembling the prepared conductive wood aerogels into flexible pressure sensors.A simple carbonization process is used to convert the prepared wood aerogel into conductive carbon wood aerogel(CWA),and then the thermoplastic polyurethane solution(TPU)is uniformly covered on the surface of the carbon wood aerogel by soaking,suction filtration-drying method.The flexible electrode and the conductive composite material prepared by the screen printing method are assembled into a flexible pressure sensor.This article sets up a series of experiments to explore the effect of carbonization temperature and TPU concentration on sensor performance.Experiments have found that as the carbonization temperature increases,the sensitivity of the sensor first increases and then decreases.When the carbonization temperature is 800°C and900°C and the TPU concentration is 6%,the CWA/TPU composite material has super compressibility and can be bent and folded at will.The prepared flexible pressure sensor has high sensitivity(76.18 k Pa^-1),and Low hysteresis(5.2%),wide detection limit range(0.6 pa-100 k Pa)and excellent durability(10000 cycles).The sensor can not only monitor tiny pressure signals such as breathing and wrist pulse in real time,but also reliably detect human movement(finger bending,plantar pressure).A simple in-situ method of polymerizing pyrrole was used to grow polypyrrole conductive material on the surface of wood aerogel,and a flexible pressure sensor of polypyrrole/wood aerogel(PPy/WA)was prepared and the effect of pyrrole(Py)concentration on sensor performance was discussed.influences.With the increase of Py concentration,the amount of PPy on the surface of wood aerogel gradually increases.When the concentration of pyrrole is 0.5 mol/L,the PPy on the surface of the wood aerogel begins to agglomerate in a large amount.Experiments have found that as the concentration of Py increases,the sensitivity of the sensor increases first and then decreases.When the Py concentration is 0.3 mol/L,the sensitivity of the sensor reaches51.53 k Pa^-1.