At http://www.nbcnews.com/technology/futureoftech/tiny-medical-electronics-dissolve-harmlessly-inside-your-body-6146659

Tiny medical electronics dissolve harmlessly inside your body

Beckman Institute / University of Illinois / Tufts University

A silk-silicon circuit dissolves in water

A team of researchers has created a form of electronics that can be implanted in a patient's body then forgotten about — because the implants will dissolve within a week or two. Such safe and hassle-free electronic monitoring could revolutionize medical care.

Implanting devices in the body is nothing new, but usually the risk is only worth it for life-threatening problems: a pacemaker, for instance, or an insulin pump. But there are lots of situations where constantly monitoring some vital statistic would be useful. A thermometer or blood sugar monitor could help make sure a post-operative patient is safe during the critical first week — but the stress and cost of the implantation and removal operations can't be justified.

But what if the implant was inexpensive and made of nontoxic materials that would break apart and be resorbed into the body after a set period of time? That's just what researchers, led by Professor Fiorenzo Omenetto at Tufts and John A. Rogers at the University of Illinois, have accomplished.

The tiny devices, which they call "transient electronics," are made from silicon and silk. Silicon is, of course, a normal material for electronics, but it is also a common organic element found in our own bodies, and small amounts of silicon are easily dissolved in water or bodily fluids. Modern manufacturing techniques allowed the team to make silicon circuits only tens of nanometers thick, meaning they are well within healthy quantities to be ingested.

Circuits are usually mounted on plastic or some other non-soluble material. But on transient electronics, the circuit board is made of silk protein extracted from silkworm cocoons, a material that is strong but also very biodegradable. Omenetto and his team managed to adjust its properties so they can control how long it takes for the silk to degrade — meaning they can create devices that melt down after a day, a week, or... ( more at http://www.nbcnews.com/technology/futureoftech/tiny-medical-electronics-dissolve-harmlessly-inside-your-body-6146659 )