Battery-powered miniature implant for electrical nerve stimulation

The range of application of implantable stimulators in functional electrica l stimulation (FES) for therapeutic purposes and for the restoration of los t or damaged functions has steadily grown within the last 20 years. Each ti me a clinically used method is improved, a new field of FES application exp lored or basic research conducted, animal, experiments are needed to check and evaluate the findings and results. It is precisely for this use that th e stimulation system described in this paper was developed. The battery-powered single-channel stimulator can be used for the excitatio n of motor and sensory nerves with monophasic or biphasic impulses. All par ameters and functions are programmable via the bidirectional telemetry circ uit. Implant programming is achieved by a laptop computer, supported by a g raphical user interface, instead of by a specially designed programmer. The maximum settings of the stimulation parameters are: frequency 100 Hz, mono phasic pulse duration 0-8 ms, biphasic pulse duration 1.6 ms, stimulation c urrent 3 mA. The implant volume was reduced to 2 cm(3) (length 23 mm, width 13 mm, height 7-5 mm), lowering the weight to 3.6 g. Due to this small volume the implant can be used in small animals. The powe r supply via battery obviates the need for transcutaneous tunneling or perm anent external high-frequency senders and facilitates the keeping of the an imals.