Research On High-sensitivity, Wide-range And Multifunctional Flexible Piezoresistive Senso

Flexible sensors are the core components of smart wearable products,which can accurately monitor various physiological signals and motion signals of the human body,and have potential application prospects in the fields of medical care,physiological monitoring,disease diagnosis and human-computer interaction.In this subject,a wide-range,high-sensitivity multifunctional flexible sensor was prepared,and its sensing mechanism and performance were analyzed.First,three through-hole porous anodic alumina templates（AAO）with different pore sizes and pore depths were prepared by adjusting experimental parameters:AAO-0,AAO-30 and AAO-60.The pore size of template AAO-0 is 440nm and the depth is 6.9μm,the pore size of template AAO-30 is 400nm and the depth is 6.5μm,and the pore size of template AAO-60 is 390nm and the depth is 6.0μm.Then,according to the different sizes of the three templates,three corresponding through-hole conductive film models were constructed,and the stress-strain performance of the three conductive film models were compared through finite element simulation.Finally,the best stress-strain performance was selected.AAO-0corresponding to the conductive film model was used as a template to prepare a micro-nano through-hole PPy conductive film.Then,the micro-nano through-hole PPy film is spin-coated with PU to prepare the micro-nano through-hole PPy/PU conductive film.The conductive film has a front pore size of 361.54±15.97 nm,a back pore size of 364.84±15.30 nm,and a hole depth of 7.75±0.17μm,has excellent electrical and mechanical properties,and its glass temperature is 79℃.Finally,based on the through-hole PPy/PU conductive film,a wide-range,high-sensitivity,multi-functional,flexible piezoresistive sensor was prepared.The sensor exhibits a wide range of 0-16k Pa and a high sensitivity of 103.89 k Pa^-1under pressure conditions;It exhibits a high sensitivity of 0.6685%℃^-1at a temperature of0-70℃,and a high sensitivity of 0.381%RH^-1at a humidity of 20-90 RH%.The sensor can accurately respond to a variety of pressure,temperature,and humidity stimulus signals such as pulse beat,breathing activity,and water temperature changes.At the end of this paper,the electrochemical experiment of the micro-nano through-hole PPy/PU conductive film was carried out to measure the impedance spectra of the conductive film under different pressure,temperature and humidity.The equivalent circuit was constructed according to the physical structure of the conductive film and analyzed The impedance calculation formula of the equivalent circuit and the influence of frequency on impedance.In order to study the different responses of the conductive film to pressure,temperature and humidity stimuli,Zview software was used to perform parameter fitting on the measured impedance spectroscopy data.The Bode diagrams under different pressures,temperatures and humidity all show that the impedance of the conductive film decreases with the increase of frequency,and it mainly exhibits resistance behavior at low frequencies,and it exhibits both resistive behavior and capacitive behavior at intermediate frequencies.Finally,use Zview software to fit the two parameters of resistance（R）and capacitance（C）under different pressure,temperature and humidity,and explain the related reasons.The research of this subject provides theoretical and experimental support for the preparation of flexible multifunctional sensors with micro-nano structures and its response to multiple physical signals.