Effect of needle shape on performance of needle-type electro tactile display

This paper describes how the shape of micro-needle electrodes of an electro tactile display affects the tactile sensation. The electro tactile display can display the tactile sensations by stimulating tactile receptors with electric current. Micro-needle electrodes can drastically decrease the electrical impedance because the needles can penetrate through the stratum corneum which has higher impedance than dermis. 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 large radius, the needle cannot go through the surface of fingers and the impedance does not decrease. In this work, we experimentally investigated the optimum shape of the micro-needle electrodes for electro tactile display applications.