Fabrication And Properties Of Flexible Pressure Sensors Based On Bucky Gel With Micro-Ridge Structures

Flexible electronics is an emerging technology that has been developed in many fields.Wearable sensing devices with flexible pressure sensors have greatly facilitated the progress in the field of flexible electronics applications,among which capacitive flexible pressure sensors have received extensive attention due to their simple structure and high sensitivity.In this paper,the effects of uniform micro-ridge structure and novel material bucky gel on the performance of capacitive pressure sensors are introduced.The main contents and results are as follows:First,the finite element simulation analysis of the flexible pressure sensor was carried out using the electrostatic module and the mechanics module of COMSOL Multiphysics software,and the flexible pressure sensor with the dielectric layer of the plane and micro-ridge structures was designed and established,from displacement-pressure,von-Mises The effects of different microstructures on the sensor performance were analyzed from three different angles:stress-strain,relative capacitance change-stress relationship,and the flexible pressure sensor with micro-ridge structure had the highest pressure sensitivity and capacitance sensitivity;Secondly,multi-walled carbon nanotubes（MWCNTs）were treated with mixed strong acid.FTIR,XRD,and TEM analysis showed that the aspect ratio of acidified MWCNTs became smaller,and carboxyl groups and more hydroxyl functional groups were successfully introduced.The ionic liquid 1-ethyl-3-methylimidazole bis（trifluoromethane-sulfonyl）imide（[EMIM][TFSI]）,polyvinylidene fluoride-hexafluoropropylene copolymer（P（VDF-HFP））and acidified MWCNTs was prepared to a mixed solution,and a micro-ridge structural bucky gel（MBG）was prepared on a 3D printing template by solution casting method.P（VDF-HFP）and acidified MWCNTs formed a physically cross-linked three-dimensional spatial network via hydrogen bonding,[EMIM][TFSI]encapsulated in which MBG was formed.SEM analysis shows that MBG has a uniform micro-ridge structure.FTIR and XRD analysis show that MBG has highβ-phase crystallinity.Dielectric property analysis shows that with the increase of acidified MWCNTs content,MBG increases the dielectric constant and dielectric loss;Finally,MBG as a dielectric layer was sandwiched by two flexible electrodes to assemble a capacitive flexible pressure sensor with a sandwich structure.The micro-ridge structure,electric double layer（EDL）,and microcapacitance of MBG enabled the sensor with excellent electromechanical properties,such as ultra-high sensitivity of 70.783 k Pa^-1,low detection limit of 0.2 Pa,millisecond-level response time,and over 3000 cycles stability.The excellent performance enabled the sensor to effectively detect various pressures,including human finger touch,human-computer interaction,joint bending,etc.,and could also be installed on the human body or machine as a wearable electronic device.These applications make the sensor a potential candidate for a multifunctional sensing platform.