Towards on-line fingertip bio-impedance identification for enhancement of electro-tactile rendering

Research in rehabilitation engineering shows that electrodes can produce tactile sensations with appropriate electrical signals tailored to stimulate the multiple tactile receptors located under the fingertip skin. However, electrical stimulation that is suitable in terms of current or voltage level for tactile sensations experienced from an individual cannot be guaranteed for every user; the dynamic range is largely dependent on the user. An identification method is then necessary for characterizing the parameters of the skin-electrode interface circuit model as to improve rendering consistency and comfort for every user regardless of skin condition. In this paper, we focus on developing a custom-built electro-tactile display terminal for data collection and an identification method to determine the individual bio-impedance parameters based on the well-known skin-electrode interface circuit model: the Cole-Cole circuit model. The goal of this work is to develop an online identification and stimulation current control approach for enhancement of electro-tactile-based rendering in applications such as rehabilitation, sensory substitution, telepresence, etc.