Research On Multi-Surfaces PVDF Force Sensor

PVDF piezoelectric film is a kind of polymer piezoelectric materials which is featured by light, soft, easy formability, corrosion resistance, wide frequency response, good stability, etc. By utilizing its positive piezoelectric effect, various types of the flexible sensor related to mechanical quantity can be designed and has been widely applied in many fields, such as modern healthcare, ultrasonic sending and receiving, structural inspection, etc. Nowadays, many scholars’ research for the PVDF pressure sensors are almost based on planar PVDF film whose manufacturing technology is complex and have great limitations on the external form of measured objects. In order to pursue the higher sensitivity and increase the flexibility of the measurement, a PVDF force sensor with multi-surfaces is proposed in this paper.Based upon the operating principle of the PVDF piezoelectric film, we propose a PVDF force sensor with multi-surfaces which is designed by using silicone sticks as its basement and the unilaminar PVDF piezoelectric film as its the core element in this paper. By using ANSYS simulation software, we simulate the characteristic of the piezoelectric effect of PVDF piezoelectric sensor with multi-surfaces and planar PVDF sensors respectively. The results show that the sensitivity of multi-surfaced PVDF sensor is obviously greater than that of planar PVDF sensor with the same PVDF film. The charge sensitivity of six-surfaces sensor is about7times of that of planar PVDF sensor. Meanwhile, for the multi-surfaces sensors with different radius of the basal silicone sticks, the more surfaces the sensor has, the greater charge sensitivity of the sensor is.Three kinds of PVDF sensors with multi-surfaces are also produced whose radius of the basal silicone stick is2mm,2.5mm and3mm and the corresponding number of surfaces is4,3,2, respectively.The dynamic performance of these three multi-surfaced sensors is tested. The sensor dynamic performance test system is comprised of signal generator, power amplifier, vibrator, charge amplifier and oscilloscope. The results show that, for multi-surfaced force sensor with the same structure, when the sinking depth of the PVDF film between the adjacent silicone sticks in the basement equals to the radius of the silicone sticks, the output charge and the charge sensitivity of the sensor is the largest. Meanwhile, for the sensors with different surfaces, the more surfaces the sensor has, the greater the output charge and charge sensitivity are, which inosculates with the ANSYS simulation results. Both the simulation and experimental results show that, the charge sensitivity of multi-surfaces sensor is apparently higher than that of planar sensor. And we can effectively improve the charge sensitivity of the multi-surfaced PVDF sensors by increasing the number of the surface.