Design And Implementation Of PDMS Based Flexible Pressure Sensor And Array System

Flexible pressure sensors have attracted more and more researchers' attention because of their advantages of thinness,flexibility,wearability,etc.A large number of flexible sensors are used in important fields such as wearable devices,robotic perception,medical rehabilitation,and physiological signs monitoring.Capacitive pressure sensor is widely used because of its advantages of easy processing in large area and low cost.The pressure sensitive film with porous structures have attracted considerable attention for their high sensitivity without expensive silicon templates.This paper develops a process to optimize structure of the large-area porous structure sensitive film and a pressure sensor array based on the film.Through the self-made circuit board and client software,the performance of the sensor device is characterized,and a software and hardware system can be built for the human sitting posture monitoring.The pressure sensor array,combined with the mature nonlinear fitting algorithm,homogenizes the performance of each pixel in the array,and converts the capacitance value into the actual pressure value for display.The main research content includes:1.Polydimethylsiloxane(PDMS)was selected as the sensitive film of the flexible pressure sensor.By improving the fabrication process,a bi-layer porous structured pressure sensitive film with the feature of microporous in the upper layer and microporous in the bottom layer was obtained.The sensitivity of the sensor based on the film was improved in the low pressure range,and maintained the similar performance in high pressure range.At the same time,in order to facilitate the performance detection of the sensor,a multi-channel capacitance data acquisition circuit and the App display software on the mobile phone were developed.Based on the pressure sensors,the circuit and App display software,a monitoring system was developed to detect the different sitting postures.2.A flexible pressure sensor array is constructed based on the large area pressure sensitive film,the data acquisition circuit and App display software on the mobile phone were developed for pressure sensor array detection.In order to meet the requirement of pressure display of pressure sensor array and solve the problem of uneven performance of each pixel in the array,a calibration method based on least square method is proposed to improve the uniformity of the performance of each pixel in the array and convert the display from capacitance value to the pressure value.After calibration,the uniformity of each pixel in the array is improved(the coefficient of variance is reduced by more than 50%).And the single pixel on the sensor array,can more accurately and directly tell the pressure value of different weights.