Study Of Conductive Polymer-based Flexible MEMS Pizeoresistive Tactile Sensor Array

As an important kind of MEMS sensors,tactile sensors can detect extremely small changes in the environment and reflect the value of the applied force.Nowadays,with the rapid development of MEMS technology,the flexible sensors based on MEMS technology demonstrate many disadvantages,such as miniaturization,low cost and integration.Furthermore,due to the excellent performances of good flexibility and high sensitivity,flexible MEMS tactile sensors can be applied in the field of wearable devices,robot and bionic artificial limb.This paper focuses on the design and fabrication of conductive polymer-based flexible MEMS piezoresistive tactile sensor array in order to propose a tactile sensor array which possesses high sensitivity,fast response,high reliability and low crosstalk effect.The main work of the paper can be described as follows:(1)The study of the sensing mechanism and selection of pressure sensitive materials.PDMS/MWCNTs which polydimethylsiloxane(PDMS)were doped with multi-walled carbon nanotubes(MWCNTs)were selected as the pressure-sensitive materials.After systematically studying the ratio of MWCNTs and PDMS on the mechanical and electrical properties of nanocomposites(PDMS/MWCNTs),the optimal concentration was determined.(2)A sandwich-structure piezoresistive tactile sensor array was fabricated.The sensor array is composed of top electrode layer,pressuresensitive layer and bottom electrode layer.The micropyramid structure was introduced after the simulation of different geometry structures,such as microcylinder,micropyramids and so on.The sensor array was fabricated through the bonding of three layers.The static performance of a sensitivity up to-1.123 k Pa-1 in the pressure range between 0 and 900 Pa was tested using the test system built before.In addition,the sensor array shows good dynamic performance including good repeatability,fast response time,low detecting limit,abilities to detect bend force and carotid artery.(3)An improved coplanar-electrodes piezoresistive tactile sensor array was fabricated.The sensing element is composed of single electrode layer and pressure-sensitive layer.In addition,the pressure sensitive layer consists of three microstructured layers including two aspectant PDMS/MWCNTsbased films and one top PDMS-based film that are bonded together.Due to this three-layer microstructure design,our proposed tactile sensor array shows the sensitivity up to-1.10 k Pa-1,the response time of 29 ms and reliability in detecting tiny pressure.The whole design of the sensor array demonstrates excellent electrical isolation and effectively eliminates the crosstalk effect.