Piezoelectric PVDF thin films with asymmetric microporous structures for pressure sensing

We demonstrate that porous Polyvinylidene fluoride (PVDF) film can be used as a flexible piezoelectric pressure sensor with high sensitivity. Asymmetric porous structure is developed to promote larger collecting area and aligned poling direction. Film structure can be controlled by dispersing micro-scale pores in a polymer matrix with a dense top layer. Piezoelectric output is enhanced by optimization of PVDF micro-structure and electromechanical coupling efficiency. The sensitivity to pressure increased three folds with a designed three-dimensional asymmetric porous structure as compared to the bulk film without such porous structures. Direct film deposition on large size surface and pore-formation on electrode surfaces enable efficient and reliable PVDF piezoelectric sensor.