Research On Piezoresistive Force Sensor

Piezoresistive force sensors play an important role in human production and life.There are several common types of piezoresistive sensors,such as,metal strain gauges,inorganic conductive strain gauges and conductive polymer piezoresistive sensors.Conductive polymer piezoresistive sensors are the most widely used because of their simple manufacturing process,low cost,and resistant to corrosion.In addition to these common types of piezoresistive sensors,in recent years,new types of piezoresistive sensors have attracted more and more attention,especially flexible sensors with different structures.In this paper,the carbon black/silicone rubber piezoresistive sensor and the CB@PU network piezoresistive sensor were selected as research objects.We explored their working principle plus manufacturing process and tested their performances.The structure and performance of piezoresistive sensors were optimized.The specific research contents are as follows.1.Carbon black/silicone rubber piezoresistive sensors were prepared through a large number of experiments,the appropriate material ratio was obtained.The influence of conductive carbon black on the electrical conductivity of piezoresistive silicone rubber was discussed.The effects of the type and amount of carbon black filler on the piezoresistive properties of the experimental samples were studied.It was found that the electrical conductivity of the piezoresistive silicone rubber with superconducting carbon black was better than that of the ordinary carbon black.The larger the amount of carbon black filler added,the better the piezoresistive property,the higher the sensitivity of material.Piezoresistive silicone rubber sample had different sensitivity in different pressure intervals;The piezoresistive properties of piezoresistive silicone rubbers with different fillers varied with the types and properties of the fillers.It was found that the smaller the particle size of the fillers,the better the conductivity of the prepared samples.These research provide a basis for further research on conductive polymer piezoresistive sensors.2.Considering the performance and structure optimization of the piezoresistive sensor,the CB@PU network piezoresistive sensor was designed and fabricated,and the conductive mechanism of the sensor was analyzed and verified by experiments.The theoretical formula of the conduction mechanism was derived and the factors affecting the performances of the sensor network were discussed.The sensor structure were optimized considering the aspects of network structure and material selection.The effects of PU yarn density and network density on the sensor performance were discussed.The optimum preparation process was preferred.It has been found that in the micro-pressure range(0-140 Pa),the PU yarn network with higher linear density showed higher sensitivity.In the remaining pressure range(140 Pa-20 kPa),the smaller the PU yarn linear density,the higher the sensitivity of the sensor network.3.The preferred carbon black/silicone rubber piezoresistive sensor and CB@PU network piezoresistive sensor were tested for their piezoresistive properties,sensitivity,hysteresis,repeatability,response time and compressibility.The performance of the conductive polymer piezoresistive sensor has been comprehensively analyzed and explored,which provided a basis for the study of conductive polymer piezoresistive sensors.At the same time,the CB@PU sensor network not only displayed compressibility of over 97%,but also detected a wide pressure change from 25 Pa to 20 kPa.Furthermore,this sensor exhibited response time of less than 70 ms and reproducibility of over 10000 cycles.It proved that the new structure of the piezoresistive sensor had excellent electrical properties,mechanical compression properties and practical value.