Electrical system for interfacing with muscle for use in prosthetic devices

Abstract

A shortcoming of current prosthetic technology is the quality of afferent feedback to the user. Modern neural interfaces for powered prosthetic limbs do not provide their users with proprioception, the sense of the position of their limbs in space. This could be achieved by stimulating residual muscles, which contain sensory receptors that are used for proprioception. This scheme requires measurements of muscle length, velocity, and electrical activation in order to provide feedback control for the stimulation. These measurements can also be used to interpret the user's intent for movement of their prosthesis. However, no such hardware exists that is portable, low-power, and that includes functionality for muscle stimulation, length measurement, velocity measurement, and measurement of electrical activity. In this thesis, I designed and built a collection of circuitry for interfacing with muscle through various sensors and stimulation techniques in order to provide this functionality. This system may be used by researchers for taking measurements to deduce muscle state and for closed-loop functional stimulation of muscles. The system includes modules for sonomicrometry, electromyography, and functional electrical stimulation. For each module, the thesis discusses comparable devices, the theory of operation of the device, the design considerations, and and relevant results.