Preparation And Pressure Sensing Performance Study Of Cellulose-based Flexible Materials Doped With Conductive Polymers

Flexible wearable pressure sensors have become a hot research topic in fields such as pressure sensing,electronic skin,and human health monitoring.As a new generation of resistive sensors substrate,cellulose aerogels have advantages such as high specific surface area,high flexibility,and mechanical strength.However,due to their low conductivity,improving the sensitivity of pressure sensors based on cellulose aerogels is still a challenge.In this paper,two environmentally friendly pressure sensors based on different materials are introduced.One uses conductive wooden sponge with a dual-network structure,while the other uses carboxylated cellulose nanofiber composite PEDOT:PSS to prepare two highly sensitive resistive sensors.Compared with existing resistive sensors based on carbon nanomaterials and artificial polymer,the sensors prepared in this paper have the characteristics of high sensitivity,fatigue resistance,and environmental friendliness.（1）Wood sponge was prepared using a two-step chemical method.The mixture solution of PEDOT:PSS andγ-glycidoxypropyltrimethoxysilane（GOPs）was infiltrated into the wood sponge by immersion,followed by freeze-drying and heating crosslinking to prepare a wood sponge with a dual-network structure.The crosslinking effect of GOPs was verified by SEM and XPS testing.Due to its unique dual-network structure,the conductive sponge has high sensitivity(5.69 k Pa^-1),fast response time（111ms）,and fatigue resistance（stable electrical signal output after 500cycles）.In addition,the sensor has been successfully applied to monitor human motion,including joint movement and small-scale muscle movement（cheek inflation and speech recognition）.It demonstrates its potential as a widely used green pressure sensor with broad application potential in areas such as human-machine interaction and motion detection.（2）Cellulose nanofibers（CNFs）-based aerogels with conductive polymer PEDOT:PSS and glutaraldehyde（GA）as crosslinking agents were designed and prepared using sol-gel crosslinking and freeze-drying methods.Without any special treatment,these aerogels exhibit good flexibility and pressure resistance.SEM,Raman spectroscopy,and XPS analysis show that the introduction of GA not only improves the mechanical properties of the aerogels（compressive strength at 80%strain increased from 48 k Pa to 66 k Pa）but also affects the doping state of PEDOT,enhancing the sensitivity of the aerogels(from 10.65 k Pa^-1 to 15.18 k Pa^-1).In addition,the sensor has been successfully applied to monitor human motion,including both large-scale movements（joint movement）and small-scale muscle movements（cheek inflation and joint recognition）.It demonstrates its potential as a widely used green pressure sensor with broad application potential in areas such as human-machine interaction and motion detection.