Research On Flexible Tactile Sensor And Signal Acquisition Circuit Based On PDMS

Flexible tactile sensors are considered to be a way to give man-made objects a sense of human touch,and can be widely used in artificial prostheses,artificial intelligence,robots,virtual reality and other fields.At present,most researches on flexible tactile sensors focus on improving the sensitivity and response range of the sensor.There are few studies on three-dimensional force tactile perception.Sensors with three-dimensional force tactile perception capabilities can accurately perceive the magnitude and direction of force in space.,This is an important reference for manipulators to complete operations such as precise grasping and judging the direction of movement of objects.Traditional force vector sensors mostly use strain gauges,which have disadvantages such as large size and difficulty in integration.They are difficult to apply to surfaces with complex structures and are difficult to attach to joints and other parts that need to be moved.In response to this problem,this paper studies a flexible three-dimensional force tactile sensor.The specific research work and content are as follows:1.In order to overcome the problem of flexibility of strain gauge type three-dimensional force sensors,a three-dimensional force detection sensor structure suitable for flexible materials is designed.This structure improves the principle of the capacitive pressure sensor,so that it has a three-dimensional force sensing capability.The sensing unit is composed of three capacitors with common electrodes.The pressure is detected by the change of the plate spacing,the tangential force is detected by the effective area of the capacitor plate,and the tangential force is detected by the increase and decrease of the three capacitors.direction.In order to simplify the sensor model,approximate conditions are set for the theoretical model of the sensor,and the rationality of the approximate conditions is verified.The theoretical formula of the sensor is deduced under approximate conditions,and the finite element analysis method is used for simulation.It is pointed out that the planar structure of the tactile sensor has insufficient three-dimensional force sensitivity.On this basis,a microstructure dielectric layer is introduced to optimize the sensor structure.2.In order to solve the problem of insufficient stretchability of the device,compared with the existing stretchable materials,PDMS with extremely high stretchability is selected as the dielectric layer,and Ag NWs as the flexible electrode to prepare a flexible tactile sensor.The liquid phase polyol method was used to synthesize Ag NWs with high aspect ratio.In order to solve the encapsulation problem of the device,the adhesiveness and long curing time of PDMS are cleverly used to realize the interlayer bonding of the encapsulation layer and the dielectric layer.Using the results of theoretical calculations,the introduction of a micro-structured dielectric layer into the fabricated flexible tactile sensor greatly improves the sensitivity of the device.The pressure sensitivity is0.55 k Pa^-1,and the tangential force sensitivity is 0.6 N^-1.After testing,the device has good bendability,stretchability and repeatability.3.Aiming at the small output signal and large parasitic capacitance of the prepared flexible tactile sensor,AD7747 was selected as the capacitance acquisition chip to construct a signal acquisition system.The system can collect and display four-channel capacitance signals at the same time,which is of great significance for the commercial application of sensors.