A flexible finger-shaped tactile sensor based on electrical impedance tomography

We developed a flexible, three-dimensional finger-shaped tactile sensor that maps contactinduced electrical changes using electrical impedance tomography (EIT). The 3D-printed device comprises a compliant resin body, a graphite–SiO2 powder sensing layer, and ten boundary electrodes. Electrode potentials were acquired as adjacent bias-electrode pairs were switched, and conductivity-change maps were reconstructed from the measurements. Point contact produced a decrease in reconstructed effective in-plane conductance near the contact and an increase in surrounding regions. Simultaneous two- and three-point contacts were distinguished at separations of approximately 6–7 mm or more. Potential acquisition took 2.1 ms, and data transfer plus reconstruction took 26.9 ms; without image rendering, maps could be updated at approximately 30-ms intervals. These results demonstrate the feasibility of near-real-time EIT tactile sensing with a compliant finger-shaped device.