Sensitivity Research And Fabrication Of PVDF Curved Force Sensor

PVDF film's thinness and dynamic performance makes it an appropriate choice for soft, ergonomic sensor. The sensitivity of curved and plane PVDF sensor was studied and the result showed that the curved one can improve the strain distribution which makes it more sensitive than the plane one. In this paper, PVDF sensors with different radiuses were designed and tested to determine the sensitivity and the discipline of it.First, when applied concentrated force, the output voltage of curved PVDF sensor whose radius is 2mm,3mm,4mm,5mm, respectively, was simulated by using the finite element simulation software, ANSYS. The results showed that within the range of radius we discussed, the charge sensitivity increased as the radius of substrate decreased. The output voltage of plane PVDF sensors with the same base length of the curved ones were simulated, the results showed that curved sensor's sensitivity was higher than the plane one. By further research, the area integration of strain increased when the radius decreased was the reason that PVDF curved sensor with less radius generated more charge.Second, curved sensors whose radius is 3mm,4mm,5mm, respectively, were fabricated by using semi-circular silicon as its basement. The force was generated by function signal generator, power amplifier and exciter, as the same time, CL-YD-303 piezoelectric force sensor was used to calibrate the force applied. The charge generated from the sensor was converted into a voltage by using the charge amplifier and the output voltage was displayed by oscilloscope. The result of experiment was, the charge sensitivity increased as the radius of substrate decreased within the range of radius we discussed, which matches the simulation result.Last, seven PVDF sensors based on PDMS with different radius and different number of curves were designed and fabricated, then a concentrated force was applied on these sensors' top. The result showed that the sensitivity of curved sensor increased as the radius of substrate decreased and had nothing to do with the number of the curves. So 2mm single curved sensor was chosen to detect sphygmus. The sensor can detect the people's sphygmus accurately and the heart rate, blood pressure can be analyzed by the curved of sphygmus.In conclusion, within the range of radius we discussed, the charge sensitivity increased as the radius of substrate decreased. The sensor based on PDMS was fabricated to detect sphygmus accurately.