Gao, Zhaolin2021-09-242021-09-242021-05https://hdl.handle.net/11299/224465University of Minnesota M.S.M.E. thesis. May 2021. Major: Mechanical Engineering. Advisor: Ping Zhao. 1 computer file (PDF); vii, 25 pages.Piezoelectric materials are one of the currently smart materials. They have achieved great success in biologic medical and electrical applications, as fluorocarbon coatings and other areas. They have shown thriving prospects in the ongoing research and commercialization process. To improve the material’s piezoelectricity, a Polyvinylidene Fluoride (PVDF) sensor with integrating nanoporous structures was developed and fabricated. Several sets of samples with different porosities from 0% to 42.0% were made. The porosity effect on the sensor samples was studied under tensile loading, and the piezoelectric coefficient d31 was characterized. The results showed that the d31¬ value increased from ~15.8 pC/N to ~51.3 pC/N as the porosity increased from 0% to 23.7%. With a further increase in porosity, the d31 value had a considerable declining trend. It is clear that the sensor exhibited the highest piezoelectric effect when the porosity was 23.7%. The study suggests that nanoporous-structured PVDF sensor has good characteristics to generate electric voltage, and the sensor with 23.7% porosity shows the best performance for sensing purposes. Meanwhile, to investigate the sensing effect of the PVDF sensor, a set of cyclic loading was applied to the sensors, and the results indicated that the sensors can properly detect dynamic loads ranging from 0 to10 N. The output signals from the sensors and results in the relationship between their porosity and the characteristic of the membrane preparation conditions can offer interesting perspectives for the advancement of sensor design.enNanoporous structurePiezoelectric polymersPorosity effectPVDFThesis or Dissertation