Ion-Based Dynamic Tactility for Healthcare and Robotics

Human skin has different types of tactile receptors that allow distinguishing of mechanical stimuli and temperature. The receptors are composed of ion conductors and their operation is based on the dynamics of the ions. A large number of thermoreceptors and mechanoreceptors are spatially distributed in the dermis, hence the spatial profiles of strain and temperature on the skin can be perceived distinctively. The viscoelastic deformability of the ionic receptors maintains stable electrical signals under large shear strains. This talk presents artificial ionic receptor designs that can simultaneously detect thermal and mechanical information. 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 the strain. In the fast transient somatosensory processing, the ensemble of the first spikes in the spike trains encodes the dynamic tactile information. This talk proposes artificial dynamic sensory systems based on a new concept, position-encoded spike spectrum (PESS).