Design And Research On A New Distributed Capacitance Based Flexible Tactile Sensor

Tactile sensors are widely used in the field of medical apparatus, sports, bionics device, robots control and ergonomics, etc. As the technology developing and people's living standard improving, tactile sensors are due to have good prospect and marketing potential.This paper first analyzed the development status of tactile sensors and made a comparison of the working principle, advantages and disadvantages of some common tactile sensors, such as piezoresistive tactile sensor, piezoelectric tactile sensor and capacitive tactile sensor. Then analyzed the working principle of capacitive tactile sensor using large deflection theory, and worked out the relationship between the capacitance output and the force input, and verified it by making finite element simulations with COMSOL Multiphysics software. After analyzing the basical processing steps of the flexible printed circuit board(FPCB), we designed and fabricated the main frame of the new distributed capacitance based flexible tactile sensor with FPCB technology. The designed tactile sensor is comprised of four layers: top electrodes layer, bottom electrodes layer, spacer layer and contact points layer. We also proposed a new signal processing circuit of the tactile sensor with commercial capacitance-digital conversion chip named PCap01 from ACAM to read out the signal and send it to host computer. With the designed dedicated software, the host-computer can display the real-time tactile force from the sensor visually. We fabricated 9 different tactile sensors with different kind of flexible printed circuit board and different thickness of spacer layer, and compared the experiment results of their measurement range, sensitivity and linearity. The results show that the tactile sensors with different measurement range and sensitivity can be fabricated by choosing different parameters, and can meet different application requirement.The distributed capacitance based flexible tactile sensor we proposed this paper is flexible, low cost and easy to fabricate with simple structure and adaptable. Experiments show that it can realize the function of tactile force detection. This paper offers some theoretical support and a new design concept for the following tactile sensor design.