Flexible Capacitive Dual-mode Sensing Sensor Array Based On Screen Printing

Flexible sensors have been intrigued more and more attention in recent years.It shows great application prospects in electronic skin and wearable devices.Domestic and foreign scholars have successfully fabricated some flexible sensors using different materials and processes.However,there are technical bottlenecks in the controllable processing and manufacturing of multi-mode and array flexible sensors,which need to be further studied.In this thesis,the design and fabrication process of the flexible dual-mode sensor array are studied.The main research contents of the thesis are as follows:Based on the sensing mechanism of parallel plate capacity,a dual-mode flexible capacitive sensor array was proposed,which consists of non-contact and pressure sensing.The dualmode operating characteristics of the sensor were simulated by finite element analysis.The sensor array electrodes with high conductivity and bending resistance were fabricated by screen printing process,which is controllable processing and large-scale fabrication.Digital laser engraving was used to accomplish the fabrication of dielectric layer template,and the dielectric layer with conical microstructure on the surface was prepared by PDMS molding process.The surface of the electrode layer and the dielectric layer were activated by plasma and then encapsulated.A dual-mode flexible capacitive sensor array with 8×8 cells was fabricated.The performance parameters and operating characteristics of the sensor were tested.In the non-contact mode,the close objects within 20 cm of the sensor surface could be detected,and the maximum capacitance variation was-38.5%.The detection limit of the sensor in pressure mode is as low as 10.2 Pa,and the sensor has been demonstrated excellent stability and accuracy after 10 000 pressure cycle tests.A detection system,which includes signal acquisition circuit of capacitive sensor array and data visualization software,was built to detect the weak capacitive signal and display the signal.The signal acquisition circuit consisted of capacitance digital conversion,lineselection circuit,microprocessor and other modules.The data of the sensor unit was read by turn through line scan,and the capacitance response amplitude of the sensor array was displayed in the data display software in real time.In the non-contact mode,the distribution position of the non-contact object above the sensor array can be detected by the signal detection system of the flexible capacitor dual-mode sensor array.In the pressure mode,different pressure sizes and pressure distribution locations can be distinguished.The flexible capacitive dual-mode sensor array designed in this thesis has advantages of low cost and controllable processing.The signal detection system can realize the perception of non-contact mode and pressure mode of the object,which has an important application value in electronic skin,human-computer interaction and other aspects.