STANFORD, Calif. – A new ultrasensitive
electronic skin can detect chemicals and biological molecules in addition to sensing
an incredibly light touch. And now, this “superskin” can be powered
by stretchable solar cells, opening up more applications in clothing, robots, prosthetic
limbs and more.
Researchers at Stanford University are making the skin self-powering,
using polymer cells to generate electricity. The new cells are not just flexible
but also stretchable. They can be stretched up to 30 percent beyond their original
length and snap back without any damage or loss of power.
The artificial skin’s foundation is a flexible organic transistor
made with polymers and carbon-based materials. To allow touch sensing, the transistor
contains a thin, highly elastic rubber layer molded into a grid of tiny inverted
pyramids. When pressed, this layer changes its thickness, altering the current flow
through the transistor. The sensors have from several hundred thousand to 25 million
pyramids per square centimeter, depending upon the desired level of sensitivity.
The foundation for the
artificial skin is an organic transistor made with flexible polymers and carbon-based
materials. Courtesy of L.A. Cicero.
To detect a particular biological molecule, the surface of the
transistor must be coated with a different molecule that binds to the first one
when both come into contact. The coating layer has to be only 1 or 2 nm thick. The
sensor can be adjusted to detect chemical or biological materials.
The team members successfully demonstrated the concept by detecting
a certain kind of DNA. They are now working to extend the technique to detect specific
protein biomarkers that could be useful for medical diagnostics. The same approach
can also be used to detect chemical substances in either vapor or liquid environments,
Regardless of what the sensors detect, they transmit their data
to the processing center, whether a human brain or a computer, via electronic signals.
Running on solar power, the sensors are light, mobile and simple to use.
The discovery has opened the door to many possible applications.
Its stretchability offers the potential to bond solar cells to curved surfaces such
as car exteriors or architectural elements without cracking or wrinkling. One day,
the innovation could even allow robots and other devices to perform functions that
human skin cannot.
The research appeared online Feb. 25, 2011, in Advanced Materials
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