A multichannel, neural interface for the peripheral nervous system

A practical interface to the peripheral nervous system (or to the spinal cord) that could be used in a neuroprosthetic application must have two features: it should be able to selectively stimulate a large number of individual muscle groups in a highly specific fashion; and it should also be able to stimulate these muscles in a broadly graded fashion in a manner similar to the way they are stimulated naturally. We have developed a new type of silicon based microelectrode array which consists of 100 penetrating needles that project out from a thin silicon substrate. We have developed such an electrode array and have evaluated it in a series of acute implantations in cat sciatic nerve. Using a high velocity insertion technique, the array can be inserted through the epineurium and perineurium with little damage to the propagation of neural activity through the implantation site. The array records single- and multi-unit sensory information. It is capable of generating muscle twitches with single, biphasic 200 usec current pulses in the 1-10 microampere range.