Tiny,
fully biocompatible electronic devices that are able to dissolve harmlessly
into their surroundings after functioning for a precise amount of time have
been created by a research team led by biomedical engineers at Tufts University
in collaboration with researchers at 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 that can become compost rather
than trash.
“These
devices are the polar opposite of conventional electronics whose integrated
circuits are designed for long-term physical and electronic stability,”
says Fiorenzo Omenetto, professor of biomedical engineering at Tufts School of
Engineering and a senior and corresponding author on the paper “A
Physically Transient Form of Silicon Electronics” published in the
September 28, 2012, issue of Science.
“Transient
electronics offer robust performance comparable to current devices but they
will fully resorb into their environment at a prescribed time—ranging from
minutes to years, depending on the application,” Omenetto explains.
“Imagine the environmental benefits if cell phones, for example, could
just dissolve instead of languishing in landfills for years.”
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.
“While
silicon may appear to be impermeable, eventually it dissolves in water,”
says Omenetto. The challenge, he notes, is to make the electrical components
dissolve in minutes rather than eons.
Researchers
led by UIUC’s John Rogers—the other senior and corresponding author—are
pioneers in the engineering of ultrathin flexible electronic components. 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, or assimilated. 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.
Source: Tufts University
