Three-dimensional Network Structural Flexible And Wearable Stress Sensors Based On Triboelectrification Effect

With the development of technology and social of progress,the level of medical treatment has been continuously improved,and health has become an increasingly concerned issue.Besides going to the hospital regularly for medical examination,people prefer to have a device that can continuously monitor their health.Using motion monitoring and analyzing the data detected by sensors to judge the health status is a common way for researchers.In order to better realize the continuous monitoring of human health and wearability,we need to prepare a compressible sensor with an available materials and good flexibility without power supply.Using the ubiquitous phenomenon of triboelectrification effect to prepare a stress sensor can not only solve the problem of material selection,but also achieve continuous monitoring.The triboelectric stress sensor designed at present still has the disadvantages of insufficient use of friction material,performance instability,hydrophobicity,air permeability and water permeability are poor,high cost can not be better applied in wearable field.Based on the advantages of the triboelectric stress sensor,our work overcomes the above shortcomings and further optimizes the performance of the sensor.Three kinds of triboelectric stress sensors based on three-dimensional network structure are designed,which make full use of friction materials and improve the required performance.First,a sandwich structure triboelectric stress sensor with compressibility was prepared by combining the silicone rubber aerogels with graphene aerogels which have excellent conductivity and high elasticity.It is found that the friction materials have good hydrophobicity by measuring their contact angle.The sensor has different electrical signal output under different stress and has certain sensing performance.Secondly,the compression performance and flexibility of the stress sensor are further optimized.A triboelectric stress sensor with excellent flexibility and compressive stress was prepared by changing the triboelectric materials and the sensor structure.Conductive sponge acts as the electrode,TiO₂ particles and silicone rubber work as the triboelectric layer.The mechanical properties of the stress sensor were characterized.When the compressive strain reaches 80%,the compressive stress is 960 kPa,it indicates the stress sensor can withstand the pressure produced by human motion.By measuring the contact angle of the stress sensor,it has strong hydrophobic performance,the contact angle is about 130°.Finally,a hybrid hierarchical triboelectric sponge sensor for kinematic sensing was fabricated by a green,simple and low-cost method.The sensor has high compressive strength?404 kPa?and sensitivity?3.06 V/kPa?,good stability,water vapor permeability and air permeability.And it is found that the air permeability of the sensor is better than the traditional fabric with previous literatures.Sensors applied to gloves and insoles can monitor human motion well.