Researchers at the University of Illinois at Urbana-Champaign and Tufts University say they have invented functional electronic implants that can dissolve after programmable time periods. To demonstrate the system, which could aid in healing during the first few crucial days after an operation, they implanted one in a rat. It created a temporary temperature increase to sterilize a wound, and then it dissolved after 15 days. The researchers reported the development this week in the journal Science.

Biomedical researchers are turning to the idea of “programmable degradation” because it is difficult to develop materials that remain compatible with human tissue over the long term. Medical implants or drug-delivery systems that do their work and then disappear are ideal. To develop the electronic implants, the researchers encased them in silk. That material’s characteristics, particularly its crystallinity, can be adjusted so that its degradation time can be anywhere from seconds to years.

The electronics inside the silk were based on nanometers-thick sheets or ribbons of silicon, called silicon nanomembranes. The materials have been previously used to make experimental transistors, diodes, complementary logic devices, and photocells for flexible surfaces. Whereas a conventional silicon wafer or a chip would take about a thousand years to dissolve in biofluids, says John A. Rogers, who led the research at the University of Illinois, a nanomembrane is gone in a couple of weeks.