Miniature ultrasonically powered wireless nerve cuff stimulator

We present a wireless neural stimulator composed of only three discrete components. The capsule was 8 mm long and was designed to be clasped directly upon a peripheral nerve. Power was supplied by low-intensity 1 MHz ultrasound transmitted into the body. The prototype was capable of generating currents in excess of 1 mA. For in vivo testing the device was implanted in a rat hind limb on the sciatic nerve, and when insonated with pulse intensities of 10-150 mW/cm2 the stimulator excited motor axons inducing predictable contractions of the lower leg muscles.