Microfabricated Needle-Arrays for Stimulation of Tactile Receptors

Abstract

This paper describes electro tactile display with micro-needle electrodes. The electro tactile display can display the tactile sensations by stimulating tactile receptors with electric currents. Micro-needle electrodes can drastically decrease the electrical impedance because the needles can penetrate through the stratum corneum which has higher impedance than dermis. In addition, adjusted length of the needle allows us to stimulate the tactile receptors with no pain. The shape of micro-needle electrodes of an electro tactile display affects the tactile sensation. When the tip radius of the needle is too small, the impedance between finger and micro-needles becomes large due to the small contact area. On the other hand, when the needle tip has a large radius, the needle cannot go through the surface of fingers and the impedance does not decrease enough. In this work, we developed fabrication processes of a micro-needle array and an electrotactile display using the micro needle electrode array. We experimentally confirmed the superiority of needle electrode devices to flat devices and deduced the optimum shape of the micro-needle electrodes for electro tactile display applications.