Robert F. Service in Science:
Implanted electronics can steady hearts, calm tremors, and heal wounds—but at a cost. These machines are often large, obtrusive contraptions with batteries and wires, which require surgery to implant and sometimes need replacement. That’s changing.
…Xudong Wang, a bioelectronics expert at the University of Wisconsin in Madison, is developing miniature, wireless devices that take advantage of a technology pioneered by others to convert the body’s motion into electrical current. In one study reported on 29 November in ACS Nano, a fingertip-size generator that delivered a stream of tiny electrical pulses to wounds on rats’ skin sped healing. And at the meeting, Wang described similar generators that mimic commercially available implanted electrodes meant to help patients with obesity lose weight. These devices stimulate a branch of the vagus nerve, which runs from the colon and stomach to the brain stem, helping relay signals of fullness after eating. Available devices are pacemaker-size and contain batteries that often need replacement, requiring repeated surgeries. Wang and his colleagues wanted to see whether their much smaller device, which requires no batteries, could do the same job. They implanted their device on the outer wall of a rat’s stomach, so the organ’s motions during eating would power the generator. At the meeting, Wang reported that animals with the generator ate at normal times, but less than control animals. The rats lost 38% of their weight over 18 days, at which point their weight stabilized.