A long sought goal in the development of neuroprosthetics and also in certain medical therapeutics is the wireless stimulation of specific areas of the brain and CNS. We explore an innovative approach to solving this problem that utilizes implanted piezoelectric microchips that convert applied ultrasound to electrical energy sufficient to stimulate excitable tissue. Pilot experiments show that 0.5 ms pulses of 1 MHz ultrasound will remotely activate millimeter-order sized chips of PZT piezoceramic implanted near the frog sciatic nerve and produce a muscle contractile response. This observation suggests a new minimally invasive approach to electrical stimulation of both the peripheral and central nervous system. The microchips are diced from bulk ceramics and sufficiently small in some applications to be introduced into tissue by way of a syringe needle. Experiments suggest the potential to activate the chips at many centimeter depths by a handheld device producing average ultrasound power levels comparable to that used in diagnostic imaging. We propose to investigate the potential for CNS application by employing a rat model. We will evaluate various chip designs, characterize their performance in mock tissue phantoms, and then test their ability to activate rat CNS motor control centers. We envision such an approach may be the basis for development of new neural technologies and has a number of potential applications such as in activation of neural pathways in the brain, functional electrical stimulation, neural control, pain relief, and spinal stimulation. ? ? ?
| Gulick, Daniel W; Towe, Bruce C (2012) Method of locating ultrasound-powered nerve stimulators. Conf Proc IEEE Eng Med Biol Soc 2012:887-90 |
