Silk-silicon devices dissolve into surroundings
28 Sep 2012
Tiny resorbable semiconductors could be used for medical implants, environmental sensors and consumer electronics.
Biocompatible electronic devices that are able to dissolve harmlessly into their surroundings have been created by a research team at Tufts University in collaboration with the University of Illinois at Urbana-Champaign.
Dubbed “transient electronics,” the new class of silk-silicon devices promises a generation of medical implants that never need surgical removal, as well as environmental monitors and consumer electronics.
“These devices are the polar opposite of conventional electronics whose integrated circuits are designed for long-term physical and electronic stability,” said Fiorenzo Omenetto, professor of biomedical engineering at Tufts School of Engineering.
The futuristic devices incorporate the stuff of conventional integrated circuits – silicon and magnesium – but in an ultrathin form that is then encapsulated in silk protein.
These tiny circuits readily dissolve in a small amount of water or body fluid
“While silicon may appear to be impermeable, eventually it dissolves in water,” added Omenetto. The challenge, he notes, is to make the electrical components dissolve in minutes.
Only a few tens of nanometers thick, these tiny circuits, from transistors to interconnects, readily dissolve in a small amount of water, or body fluid, and are harmlessly resorbed. Controlling materials at these scales makes it possible to fine-tune how long it takes the devices to dissolve.
Device dissolution is further controlled by sheets of silk protein in which the electronics are supported and encapsulated. Extracted from silkworm cocoons, silk protein is one of the strongest, most robust materials known. It’s also fully biodegradable and biofriendly and is already used for some medical applications.
Omenetto and his Tufts colleagues have discovered how to adjust the properties of silk so that it degrades at a wide range of intervals.
The researchers successfully demonstrated the new platform by testing a thermal device designed to monitor and prevent post-surgical infection (demonstrated in a rat model) and also created a 64 pixel digital camera.
In the future, the researchers envision more complex devices that could be adjustable in real time or responsive to changes in their environment, such as chemistry, light or pressure.
