In vivo demonstration of ultrasound power delivery to charge implanted medical devices via acute and survival porcine studies

Abstract

Animal studies are an important step in proving the utility and safety of an ultrasound based implanted battery recharging system. To this end an Ultrasound Electrical Recharging System (USER™) was developed and tested. Experiments in vitro demonstrated power deliveries at the battery of up to 600 mW through 10 – 15 mm of tissue, 50 mW of power available at tissue depths of up to 50 mm, and the feasibility of using transducers bonded to titanium as used in medical implants. Acute in vivo studies in a porcine model were used to test reliability of power delivery, temperature excursions, and cooling techniques. The culminating five-week survival study involved repeated battery charging, a total of 10.5 hours of ultrasound exposure of the intervening living tissue, with an average RF input to electrical charging efficiency of 20%. This study was potentially the first long term cumulative living-tissue exposure using transcutaneous ultrasound power transmission to an implanted receiver in situ. Histology of the exposed tissue showed changes attributable primarily due to surgical implantation of the prototype device, and no damage due to the ultrasound exposure. The in vivo results are indicative of the potential safe delivery of ultrasound energy for a defined set of source conditions for charging batteries within implants.

Are some people suffering as a result of increasing mass exposure of the public to ultrasound in air?

“…The health risk under consideration in this paper is via different mechanisms and a different propagation path. The manufacturer refers to a published paper [123] that uses 1 MHz and includes no air in the transmission path, allowing charging at a few tens of millimetres. While the frequencies and intensities used in that study [123] would have negligible health risk through an airborne transmission path to the human, to achieve the manufacturer's goal ('a world where you could simply lift your phone in the air to charge it without needing to plug it in, no less be next to a power outlet' [9]) one would need to overcome the problems of reflection losses at the air/device interface, and absorption losses which restrict the range of the ultrasound in air.…”

Potentiality of magnetoelectric composites for Wireless Power Transmission in medical implants

“…In the second case, the 3-layers system at the resonance frequency of 70kHz, can deliver an output power of 600µW with a power density of 1.4µW/mm 3 [15], employing MetGlas, Terfenol-D and PZT-5H. In another case, an RMS magnetic field-source of 1600 A/m at 3cm of distance, generates in the ME receiver, made by Terfenol-D and PFC, a power of 200mW (2W/cm 3 ) [17].…”

“…Following these issues, researchers have been studying wireless power transmission (WPT) techniques for decades. In this case, an external source is used to transmit energy, for example acoustic [3] or electromagnetic [4], from out-body to in-body. The internal block converts the received energy into power to supply the device.…”

Left Ventricle Heart Three Dimension Mechanical Simulation for Kinetic Energy

“…In addition, power transmission effectiveness via RF is very small, with mostly heat dissipation passing through antenna. The implanted battery charging scheme based on ultrasound has been proved by [ 5]. Successfully collected 600mW through 10-15 mm of tissue depth through their invitro test.…”