Experimental validation of a polyvinylidene fluoride sensing element in a tactile sensor

A tactile sensor for robotic applications is described, inspired by the mechanoreceptors in the glabrous skin of the human hand, in order to replicate the sensory function of both slow adapting and fast adapting mechanoreceptors. Strain gauges were used for the slow adapting receptors, and polyvinylidene fluoride (PVDF) film was used to replicate the fast adapting receptors. A finite element analysis (FEA) model was used to predict the output response of the PVDF film, and verified experimentally. The PVDF film was observed to respond linearly to mechanical stress and exhibited increased gain at higher frequencies. "Ramp and hold" stimuli were applied to the tactile unit sensor, and the PVDF film only responded at contact onset and offset, similar to the response of fast adapting receptors. The PVDF acted as a dynamic sensing element for the proposed tactile sensor unit.