Capacitive Flexible Tactile Sensor Based On Inkjet Printing Technology

Due to the characteristics of high sensitivity,flexibility and high integration,wearable flexible sensors have emerged.This article aims to study a flexible capacitive tactile sensor with adjustable sensitivity,suitable for multiple occasions,fast response,low cost,detection array,positioning force,and has application potential in wearable devices and human-computer interaction.The main content and innovations of this article are as follows:(1)Complete low-cost,high-resolution,and pattern-controllable sensor electrodes through inkjet printing technology.Compared with the traditional flexible circuit electrode processing technology,the production of the mask is omitted,the cost is saved,and the problem of electrode distortion caused by the production and placement of the template is avoided.Improved the adhesion of the electrode material to the substrate.The inkjet printing process adheres to the substrate in liquid form,which largely avoids the electrode disconnection caused by the uneven surface of the substrate,and improves the stability and repeatability of the sensor.(2)An innovative micro-structured dielectric layer is proposed to meet the functions of adjustable sensitivity,precise positioning of the force,and no crosstalk between adjacent detection units.The morphology,height,arrangement,Young's modulus,etc.of the bumps are simulated,and the necessity of microstructure dielectric layer and the analysis of device repeatability and stability are put forward.Finally,simulations are performed on the parameters such as the shape,spacing,and arrangement angle of the bosses,and then theoretical analysis and summary are carried out to determine that the proposed structure meets the expected functions,and the experimental verification of the structure is completed in the sensor test chapter.(3)Test the sensor performance data to verify the simulation conclusion.In view of the high sensitivity capacitive tactile sensor's characteristic that it is very sensitive to tiny signals,this article uses a probe station with an LCR digital bridge to accurately measure the basic parameters of the sensor.Experimental data shows that the sensor has a sensitivity of 75.97%KPa^-1in the range of0-1.0 KPa,and a sensitivity of 20.46%KPa^-1in the range of 1.0-15.0 KPa.The result of the sensitivity test will increase the range or sensitivity as the innovative dielectric layer structure changes.The response time is 28 ms,the minimum resolution is 2 Pa,and the sensor can detect a pressure of 0.002 KPa.(4)Design a biological signal acquisition system based on wearable sensors.The EVAL-AD7746EB capacitance test suite converts the measurement signal into a hexadecimal digital signal through analog-to-digital conversion,and sends it to the host computer through the I²C protocol for data collection and processing of biological information.The experimental results of sensor performance test and application measurement show that the capacitive flexible tactile sensor designed in this paper has better application prospects such as positioning force and biological information collection.