A Flexible Multi-Functional Smart Skin for Force, Touch Position, Proximity, and Humidity Sensing for Humanoid Robots

Artificial smart skins capable of interacting with people and sensing environmental stimuli have become a research topic in humanoid robotic applications. However, previously reported architectures suffer difficulties in achieving concurrent multi-dimensional sensing in a simple structure with low system costs. To address this issue, in this paper, an artificial smart skin constructed with polyimide/copper/polyvinylidene fluoride (PVDF) is presented for detecting 2D-position, proximity, dynamic force, and humidity via a smart combination of piezoelectric- and capacitive-effects. Moreover, a follow-up filtering algorithm is proposed to separate and calculate the stimuli associated with capacitance changes (position, proximity, and humidity). The proposed system achieves overall force and capacitive sensitivities of 0.05 N and 7 fF, a humidity responsivity at 0.22%/RH% over a relative humidity range of 10%–90% RH, a spatial resolution of 0.29 mm. This simple-structured device supports multiple functions with low system costs, thus advancing the field of robotics smart skins.