System of interpreting somatic sensations for use with artificial hands and limbs

This study attempted to develop a prototype of an artificial arm system capable of sensing mechanical stimuli and then transferring these stimuli to the subject so that the subject experience the stimuli as the corresponding somatic sensations. In this system, the virtual sensations were evoked by electrically stimulating a sensory nerve fiber which innervates a single mechanoreceptor unit using a tungsten microelectrode that was percutaneously inserted into the median nerve of the subject. Pressure-conductive rubber was placed over a robot hand; when pressure was applied to the robot hand, the rubber could detect the pressure, which was modulated to the frequency of electrical pulses. The sensory nerve fiber (from the area corresponding to the area of the robot hand to which the stimuli were applied) was then stimulated by the electrical pulses. The system worked satisfactorily, with the subjects able to feel the pressure sensation resulting from the pressure that was applied to the robot hand. There was also a good correlation between the pressure applied to the pressure-conductive rubber and the subjective intensities of the evoked sensations.