Abstract
This paper experimentally investigate the shapes of micro-needle electrodes to effectively display tactile information by electrically stimulate tactile receptors. In our prior work, we revealed that a needle-type electrotactile display that penetrates through a stratum corneum of a finger skin can display tactile information at 20 times as low voltage as that with flat electrodes. We discovered that the needle-tip shapes greatly affected the performance of the display. When the tip radius is small, the large impedance of the electrodes results in high voltage to stimulate the receptors. On the contrary, when the tip is too large, the electrodes cannot penetrate through the corneum that has much higher impedance than dermis. In this work, we experimentally deduced the optimum shape of the needle tip using titanium micro-needles patterned by electrochemical etching. The needles can be readily applicable to efficient electrotactile displays.
