Dissolving Silver Nanowires for Self-Destructing Electronic Implants

Vanderbilt University engineers are creating silver nanowires that dissolve in cool liquid. Using silver nanowires embedded in a polymer that dissolves in water below 32 degrees Celsius - between body and room temperature - they have made a simple circuit board that, so far, turns on an LED light. "Let's say you use this technology to make an RFID wireless tag," said Leon Bellan, assistant professor of mechanical and biomedical engineering. "You could implant important information in a person, and body temperature would keep it intact. If the tag were removed or the bearer died, it would dissolve. You could use it for implanted medical devices as well – to cause them to disintegrate, it would only require applying ice to the skin." In the lab, tiny circuit boards stay operational in water warmed by a hot plate. Turning off the hot plate causes them to start dissolving in minutes. In this system, the silver nanowires are held together in the polymer so that they touch, and as long as the polymer doesn't dissolve, the nanowires will form a path to conduct electricity similar to the traces on a circuit board. Trigger the polymer to dissolve by lowering the temperature, and the nanowire network disintegrates, destroying the conductive path.