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A cross-disciplinary collaboration between Fiorenzo Omenetto, a biomedical engineer at Tufts University, Medford, MA, and John Rogers, a materials scientist at University of Illinois at Urbana–Champaign, has yielded tiny new electronic devices that completely dissolve when they are no longer needed (Science 337, 1640–1644; 2012). These 'physically transient' electronics are built from silicon, the preferred semiconductor, like other devices, but the silicon membranes in the transient devices are less than 100 nm thick. They are coated in silk packaging, processed from silkworm cocoons into thin, flexible films. Omenetto and Rogers can adjust the properties and thickness of the silicon and the silk to control the dissolution rates of the devices. The electrical components are made from magnesium, a metal whose reactivity largely excludes it from use in traditional electronics. In transient devices, however, its reactivity is a benefit. “Everything dissolves,” Rogers told NPR's David Schultz (Shots, 27 September 2012; http://www.npr.org/blogs/health/2012/09/26/161815537/medical-electronics-built-to-last-only-a-little-while).

As a case example, Omenetto and Rogers built a dissolvable implant that heats up when hit with radio waves and tested it in rodents. By increasing local temperature, the device kills bacteria to prevent infection that might otherwise occur (after surgery, for example). The implants were well tolerated in BALB/c mice and Sprague-Dawley rats. Blood vessels grew into and around the silk, and there were no signs of inflammation where the devices had been placed. The devices dissolved almost completely in about 3 weeks.

There are several potential applications of this technology, including reducing the waste stream from consumer electronics. But the medical applications offer perhaps the biggest benefits. Dissolvable implants could eliminate the need for surgical removal, reducing potential complications, enhancing patient welfare and cutting health-care costs. Devices could be programmed to monitor internal physiology and release drugs accordingly or to produce electric current to help bones heal in situ.

It may be a decade or more before biodegradable devices are available for general use. Devices would need to be tested and approved by regulatory authorities, such as the US Food and Drug Administration, before they could be marketed. Large-scale manufacturing of the devices would also need to be addressed. Christopher Bettinger, who works with organic electronics at Carnegie Mellon University (Pittsburgh, PA) but was not involved in the study, suggests that the key to further development of this technology will be identifying a specific application—a disease or symptom that could be treated with such a device.