System design and experimental evaluation of a MEMS-based semicircular canal prosthesis

The paper presents a functional architecture, system-level design, and preliminary experimental evaluation of a unilateral vestibular prosthesis. The sensing element of the prosthesis is a one-axis MEMS gyroscope. Similar to the natural semicircular canal, the microscopic gyroscope senses angular motion of the head and generates voltages proportional to the corresponding angular accelerations. Then, voltages are sent to the pulse generating unit where angular motion is translated into voltage pulses. The monophasic voltage pulses are converted into biphasic current pulses and are conditioned to stimulate the corresponding vestibular nerve branch. Our preliminary experimental evaluations of the prosthesis on a rate table indicate that the device´s output matches the average firing rate of vestibular neurons to those in animal experiments reported in the literature. The proposed design is scalable; the sensing unit, pulse generator, and the current source can be potentially implemented on a single chip using integrated MEMS technology.