Design And Fabrication Of Capacitive Flexible Tactile Sensor For Three-dimensional Force

With the development of intelligent robot technologies and intelligent prosthesis technologies,flexible tactile sensors have attracted extensive attention due to their advantages of adapting to complex surface structures of objects and completing real-time sensing.In real life,some practical application scenarios of intelligent robot,biological medicine and other fields have put forward the requirements of three-dimensional force detection for flexible tactile sensor.At present,the work of the flexible three-dimensional force tactile sensor still need further in-depth researches in terms of balancing measuring ranges and sensitivities,so new structures need to be designed to achieve high-sensitive detection of three-dimensional contact force within a certain measuring range.For the sensors involved in the designs of complex structures,the researches on the controllability of interlayer alignment and packaging processing have not got enough attention.In this paper,the structural design and fabrication of the flexible tactile sensor unit were studied,with published research in comparison,novel structural designs proposed,and the detection principle analyzed.According to the design structures,the micro-nano processing process of layered manufacturing and collective packaging was explored.The dynamic performance,repeatability and measurements of three-axis forces of the designed sensor unit were tested and analyzed.Chapter 1:The background and significance of this paper were explained,with the introdutions and comparisons of researches on three-dimensional force flexible tactile sensor at home and abroad.,to rasise the research objectives of this paper.Chapter 2:The material selections and the structure designs of the capacitive three-dimensional force flexible tactile sensor were decided.Specifically,the structure of cross-type capacitive plate pairs was designed,which can keep the overlap area of the capacitors basically unchanged during translation dislocation and compression deformation.The dielectric layer made use of the conbination of the cross-bar walls and micro-pillar arrays,providing a method th adjust force ranges and sensitivities of the sensor unit.The bump layer was adopted,corresponding to four capacitors,to realize the function of three-dimensional contact force detection.The working principle and theoretical calculation of the designed sensor were analyzed.Chapter 3:The fabrication of capacitive flexible tactile sensor unit was explored,adopting the fabrication way of layered manufacture and intergration encapsulation.The pattern of Cr-Cu capacitor electrodes was prepared on PI films by micro-nano process including photolithography and magnetron sputtering.Three methods of mold preparation for the dielectric layer were carried out to make the comparison and selection.A platform for interlayer alignment packaging was set up.Eventually it is clear that the dielectric layer mold was fabricated by the lithography and dry etching on silicon wafer,relevant operations adjustments were made to sovle encountered problems during packaging the dielectric layer and the capacitance plate layer.The bump layer is prepared by pouring PDMS to the 3D printing mold.Each layer is encapsulated by unhardened PDMS to form a unified whole sensor.Chapter 4:In order to study the performances of the flexible tactile sensor,the scanning measurement system for capacitance arrays was established,and experimental tests were carried out using the 3d force loading experiment platform from the college of mechanical engineering.The dynamic response,the measurement repeatability and sensitivities of normal and shear contact forces were tested.The experimental results showed that the developed capacitive tactile sensor unit had the application prospect for three-dimensional contact force detection.