Piezoelectric PVDF-based sensors with high pressure sensitivity induced by chemical modification of electrode surfaces

Poly(vinylidene fluoride) (PVDF), an organic piezoelectric polymer, has been extensively studied for application in flexible pressure sensors. In order to obtain a sufficient voltage output from PVDF-based pressure sensors, a poling treatment of PVDF films is necessary. Conventional poling methods generally require the application of a considerably high electric field and high annealing temperatures, which lead to an increase in the cost of sensor fabrication. Herein, we propose a method for the formation of poled PVDF films by drop-casting a PVDF-dissolved polar solution onto chemically modified electrodes and subsequent drying of the dropped solution. The PVDF-based pressure sensors in which the underlying gold (Au) electrode was modified with a thiol reagent, 1H,1H,2H,2H-Perfluorodecanethiol (PFDT), exhibited a remarkably high pressure sensitivity, while negligible sensitivity was achieved without surface modification. It was demonstrated that surface chemical modification aligns the direction of the surface dipoles. The proposed method is advantageous for controlling the polarization of PVDF films on electrode surfaces.