Study On Performance Of Flexible Pressure Sensor With Microstructures Based On Resonant Printing

Flexible pressure sensors,composed entirely of flexible materials,have been widely used in wearable devices,human-machine interaction,and healthcare due to their ability to maintain good performance under significant deformation.According to their working principles,flexible pressure sensors can generally be divided into resistive,piezoelectric,and capacitive types.Among them,resistive pressure sensors have been extensively studied due to their advantages of simple structure,low cost,and strong anti-interference ability.To meet the needs of different application scenarios,researchers have adopted microstructured treatments on a certain part of the resistive pressure sensor to improve its key performance.However,currently,the microstructure work of resistive pressure sensors is only carried out on the pressure-sensitive material layer,and the manufacturing of microstructures is plagued by low positioning accuracy,high cost,complex processes,and low efficiency in batch production,which limits the development of flexible pressure sensors.Therefore,a flexible piezoresistive pressure sensor based on microstructure is designed in this paper,and the structure of the sensor and the fabrication process of the microstructure are improved respectively.The specific research content of this paper is as follows:A flexible piezoresistive pressure sensor with microstructure added to the electrode layer is proposed to address the problem that microstructure design is rarely performed in the electrode layer of flexible pressure sensors.Based on the working principle of resistive pressure sensors,structural design and material selection were carried out for each part of the sensor.The sensor consists of four parts: encapsulation layer,piezoresistive material layer,electrode layer,and flexible substrate.The electrode layer adds microstructures between the fingers based on the forked electrode.To verify that this design can effectively enhance sensor performance,finite element simulation analysis was used to analyze two types of sensors with and without microstructure.The relationship between the load and the strain of the piezoresistive element was obtained,and the results showed that adding microstructure to the electrode layer can improve sensor performance.Furthermore,the influence of the size and arrangement of the microstructure on the strain of the piezoresistive material layer was analyzed,and the structural parameters of the sensor were optimized based on this analysis.A novel method for preparing microstructures using a resonant printing technique is proposed to address the issues of complex fabrication processes and low efficiency.First,silver nanoparticles were synthesized by a liquid-phase reduction method,and the solvent formula of the silver nanoparticle ink was studied.The addition of additives improved the viscosity and surface tension of the ink,resulting in ink suitable for resonant printing.Secondly,the process parameters involved in the fabrication of microstructure by resonant printing technology,such as needle size,number of printing layers,and printing speed,were investigated.The influence of various process parameters on the forming effect of microstructure is analyzed.Combined with the results of simulation analysis,the ideal printing parameters are determined for the preparation of microstructure.Then,each part of the sensor is prepared according to the design,and the flexible pressure sensor is fabricated after integrated packaging.Based on the existing laboratory equipment,a sensor performance test system was set up to test the basic properties of sensitivity,response time,repeatability,and hysteresis of the sensor,and to compare the sensitivity of sensors with and without microstructures.The test results showed that the sensitivity of the sensor with microstructures was significantly higher than that of the sensor without microstructures,which verified the reliability of the finite element simulation results.The highest sensitivity of the flexible pressure sensor with microstructures reached0.042 k Pa-1.In addition,this flexible pressure sensor has a response time of 72 ms,a recovery time of 102 ms,a hysteresis of 15.59 %,and a cycle stability of about 2000 times.After that,the practical application of the sensor is tested,including rigid mechanical surface pressing action monitoring,human joint movement monitoring and human throat motion monitoring,which showed that the flexible pressure sensor can accurately respond to signals of different pressures and frequencies and has potential for use in wearable devices and medical and health fields.