Flexible Capacitive Sensor Based On Miura-ori Structure

Recently,with the rapid development of wearable devices,flexible pressure sensors have a wide range of applications in physiological health monitoring,electronic skin,and biomimetic robots.Among them,capacitive pressure sensors have been widely studied because of their simple structure,low temperature coefficient,low power consumption,and fast response speed.Researchers usually improve the sensing performance of capacitive pressure sensors by increasing the relative change in distance and dielectric constant between electrodes.However,due to the increase in compressive modulus of flexible materials under high pressure,the sensitivity of the sensor decreases with the increase of pressure,which may limit the application in scenarios with preload.Inspired by Miura-ori structure,a flexible capacitive pressure sensor based on symmetric Miura-ori structure is proposed in this paper.Due to its special folding mode,the distance and opposite area between the electrodes change simultaneously in the direction of capacitance increase during the pressure process,enabling the sensor to achieve a sensitivity increase with increasing pressure within an adjustable pressure range.In addition,the sensor has high stretchability and can detect both stretched and contractive strains.The main research contents of this paper are as follows:1.Principle analysis and preparation of sensor.The working principle of the sensor is analyzed according to the change of length,width,and height of the symmetrical Miura-ori structure during the deformation process,and the effect of the cooperative of the distance and opposite area between the electrodes on the improvement of the relative capacitance change rate was revealed.The sensor is prepared by using low-cost materials such as DragonSkin and MWCNTs,as well as easy processing methods such as 3D printing,molding,and spraying.2.Performance research and simulation analysis of sensors.The deformation mode of the symmetrical Miura-ori structure avoids the sensitivity of the sensor decrease with increasing pressure within a certain pressure range.By analyzing the deformation simulation results of the sensor under different pressures,the special trend of sensitivity changes is explained reasonably.At the same time,the effects of dielectric layer thickness and composite dielectric on sensitivity and dynamic pressure range were studied.In addition,the sensor also has high stretchability,good response time,and excellent stability.3.Research on the application of sensor.The excellent sensing performance of the sensor enables the detection of human signals such as pulse,breathing,voice,wrist bending,and gesture recognition.In addition,with the special trend of increasing sensitivity with increasing pressure of the sensor,an underwater testing device was built to explore its application under preload,achieving water depth detection,underwater reef collision detection,and identification of biological and non-biological proximity detection.In this paper,the symmetric Miura-ori structure is introduced into the dielectric layer and electrode layer for the first time,and the sensitivity is improved through the synergistic effect of the distance and opposite area changes between electrodes.This provides an alternative strategy for the design of the traditional flexible capacitive sensor based on the microstructure and porous structure,and opens up a new way for the preparation of multi-functional and adaptable flexible sensors.