Design And Application Of Capacitive Flexible Sensor Based On Organic-Inorganic Composite Film

Electronic skin has been widely used in artificial intelligence,wearable devices,intelligent robots and other fields,with a considerable applications and development.As an important part of electronic skin,capacitive sensor has received increasing attention.Flexible polymer materials have been applied as the dielectric layers or substrates of the sensors to replace the hard material of the early sensors which can not withstand large deformation.However,low dielectric constant of polymer materials leads to the low signal-to-noise ratio(SNR)of capacitive sensors,which limits the application range.Aiming at the problems that most of the current capacitive sensors cannot withstand large strains and susceptible to external interference,this paper proposes a strategy for flexible capacitive sensors based on organic-inorganic composite films,and conducts a series of system studies.The main research contents of this paper are as follows:Polyacrylate matrix was used as the dielectric film,and several typical flexible electrodes:carbon grease,silver@copper,Wacker commercial electrode and carbon nanotubes were selected.The conductivity,stability,service life,cost of different flexible electrodes are investigated.And their impact on sensor performance,application scope and limiting factors in daily life are compared.Through comparison and comprehensive analysis,carbon nanotubes are considered as the most promising flexible electrode for sensors because of their excellent electrical and mechanical properties.High-dielectric BT nanoparticles were composited with butyl acrylate and glycidyl methacrylate copolymer[p(BA-GMA)]to improve the dielectric constant and the signal-to-noise ratio(SNR)of the capacitive sensor.The effect of the content of BT nanoparticles on the sensing performance of BT/p(BA-GMA)composite film was systematically studied.The optimal volume fraction of BT nanoparticles is determined by analyzing and testing the sensing range of the BT/p(BA-GMA)composite film-based sensor,the corresponding capacitance change,SNR and linearity.The flexible capacitive sensor with high SNR and large tensile deformation was fabricated.The sensor based on BT/p(BA-GMA)composite film as dielectric layer and SWCNTs as the electrode layers was applied to measure the bending of finger,arm and other joints,monitor small weights and non-contact measurement.The results confirmed that the flexible capacitive sensor showed significant linear output stability,which can be applied to real-time dynamic measurement in complex surface like electronic skin.