Artificial multimodal receptors based on ion relaxation dynamics

Human skin has different types of tactile receptors that can distinguish various mechanical stimuli from temperature. We present a deformable artificial multimodal ionic receptor that can differentiate thermal and mechanical information without signal interference. Two variables are derived from the analysis of the ion relaxation dynamics: the charge relaxation time as a strain-insensitive intrinsic variable to measure absolute temperature and the normalized capacitance as a temperature-insensitive extrinsic variable to measure strain. The artificial receptor with a simple electrode-electrolyte-electrode structure simultaneously detects temperature and strain by measuring the variables at only two measurement frequencies. The human skin-like multimodal receptor array, called multimodal ionelectronic skin (IEM-skin), provides real-time force directions and strain profiles in various tactile motions (shear, pinch, spread, torsion, and so on).