Biodegradable Electronics

Biodegradable electronics are not a usual feature of our high tech society in which our devices are obsolete in two to three years. Also biodegradable electronics implies disposable units and this limits the materials that can be used.

Currently the ‘clever bit’ of our electronics is silicon based and silicon is biofriendly. It oxidizes and dissolves in water, so this is a starting point from which a large team led by Rodgers and Omenetto took up the challenge for developing biodegradable electronics, which they call transient electronics (1,2).

At normal body and most environmental situations, the solubility of silicon is very low and their solution is to use it in very thin nanomembranes, thus there is very little of it to go into solution. So nanomembranes of silicon, with some metal oxides to make semiconductors, form the basis of electronic devices that could be implanted into a person, an animal or perhaps a sensitive environmental situation which would make it difficult to retrieve.

The proof of principle gadget was a circuit embedded in a wound which could be heated to act as a bacteriocide. It worked like a charm, the wound healed and the device was absorbed into a now happy rat. No antibiotics were required.

The next problem is that we might want some circuits to last longer than others and making them thicker isn’t a very good option for a uniform production process. The answer the team used was to sign up some silk worms into the work force. The fibroin in silk forms sheets which then stick together via weak hydrogen bonds. The nanomembranes can be coated with dissolved silk, which is then allowed to re-crystalize. This controls the subsequent dissolution of the coating and then the device.

A number of devices are under lab test and one can imagine that in addition to the bacteriocide concept mentioned above, the biodegradable electronics could be used for sensors (chemicals released by sepsis or temperature changes for example after surgery) or for a controlled release of a drug. With modern wireless technology, perhaps the release and data acquisition could be controlled and read by our smartphones.


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