The same researchers who last year developed "electronic tattoos" that bend and stretch on skin are now unveiling similar ultra-thin electronics, only these dissolve when their job is done.
Made of silicon, magnesium, and magnesium oxide and surrounded by a protective layer of silk, these "transient" electronics aren't built to last but rather to melt away and, in the process, reduce the need to pass or surgically remove tiny medical implants, researchers from Tufts and the University of Illinois write in the current issue of Science.
The researchers -- who have begun using their devices on rats to heat wounds, thereby protecting them from bacterial infection -- report that they had to use extremely thin sheets of silicon called nanomembranes to get the electronics to dissolve in hours or days instead of years.
As for concerns of toxicity, they say the materials are non-toxic and that in one device they used less of the mineral magnesium than is found in a multivitamin.
The researchers also used silk collected from silkworm cocoons to control the speed of disintegration. Because the structure of the silk determines the speed at which it dissolves, they were able to control its final properties, right down to how long the device will remain solid, by manipulating the silk's crystallization.
Possible medical applications include sensors implanted into brains and hearts, the slow release of drugs into the body, and temperature sensors that help keep wounds and surgical sites clean.
And the researchers point out that it would be better environmentally to make dissolvable (instead of disposable) electronics, such as cameras and cell phones, that are engineered to last a certain amount of time before simply melting away. Such a future may not be so far away.