Research On Flexible Piezoresistive Sensors And Electric Heating Elements Based On Polypyrrole-coated Fabrics

With the development of wearable electronic devices,flexible pressure sensors and electric heating elements,as important components of flexible electronic devices,have attracted more and more attention from researchers.The current research is mainly focused on improving the performance of sensors and electric heating elements.Polypyrrole coated fabric has attracted people's attention due to its excellent flexibility and conductivity,as well as its low cost,renewable and environmentally friendly advantages,and has become an important conductive material for the preparation of flexible piezoresistive sensors and electric heating elements.In this paper,high-performance flexible piezoresistive sensors and electric heating elements are prepared based on textile materials and polypyrrole materials,and their performance is tested and analyzed.The polypyrrole coated fabric was prepared by in-situ polymerization.The effects of substrate type,polymerization time and pyrrole concentration on its surface morphology,conductivity,sensing performance and electric heating performance were discussed,and the best process parameters were obtained.Tests show that the substrate type is roving cotton fabric,the polymerization time is 90 min,and the concentration of pyrrole is 0.5 mol/L,which is the best preparation condition.The resistance of polypyrrole-coated cotton fabric is 7.544?,and the surface resistivity is11.6?/sq.It has a working range of 0?16 k Pa and a sensitivity of up to 60.23 k Pa^-1.It has excellent electrical heating performance,including a rapid temperature rise response of 100 s,a maximum equilibrium temperature of 115.5?and a thermal stability of 7200 s.In order to further improve the performance,the fabric is modified with dopamine,and then the polypyrrole dopamine coated fabric is prepared by in-situ polymerization.In order to explore the effect of dopamine coating on performance,different pyrrole concentrations were set.The morphology,conductivity,sensing performance and electric heating performance of the pyrrole under different concentrations of pyrrole were studied,and the polypyrrole dopamine coated fabric prepared at the concentration of 0.3 mol/L pyrrole had the best performance.The test shows that the electrical resistance of the polypyrrole dopamine coated fabric is as low as 6.93?,and the surface resistivity is as low as 10.8?/sq.It has a working range of 0-16 k Pa,a sensitivity of 84.46 k Pa^-1,and a repeatability of 3000 s.Excellent electric heating performance,including 100 s rapid heating response,120.6?maximum equilibrium temperature.The flexible piezoresistive sensor made of polypyrrole dopamine coated fabric is installed on the wrist radial artery,fingers,wrist and knee to detect pulse signals,small signals and human movement,which proves that the flexible piezoresistive sensor is capable of detecting weak signals and motion.The ability to place the heating element made of polypyrrole dopamine coated fabric on the knee for stable and controllable heating.It shows the development prospect of polypyrrole dopamine coated cotton fabric in the field of smart wearable devices.