Electrotactile Display with Real-Time Impedance Feedback Using Pulse Width Modulation

An electrotactile display is a tactile interface composed of skin surface electrodes. The use of such a device is limited by the variability of the elicited sensation. One possible solution to this problem is to monitor skin electrical impedance. Previous studies revealed a correlation between impedance and threshold, but did not construct real-time feedback loops. In this study, an electrotactile display was constructed using a 1.45 μs feedback loop. Real-time pulse width modulation was proposed, and the relationship between skin resistance and absolute threshold was measured to find a function for determining a suitable pulse width from skin resistance. An evaluation experiment revealed that the proposed algorithm suppressed spatial variation and reduced temporal change.