Nanowire transistors offer low-voltage operation and fast switching speeds in a flexible surface. Whereas Bao’s devices require about 20 volts to operate, Javey’s need less than five volts.
Javey has made sensor arrays that are about 50 centimeters squared. Bao has built circular arrays that are just over 10 centimeters in diameter. Both researchers say the size of their devices is limited only by the tools in the lab–in Javey’s case, the size of the contact printer, and in Bao’s case, the size of the mold used to shape the PDMS.
Artificial skin could offer major advantages for robotic manipulation, says Matei Ciocarlie, research scientist at Willow Garage, a personal-robotics company based in Menlo Park, California. When a robot is manipulating an object, that object may often be hidden from cameras and other sensors, so tactile sensing can provide useful feedback. Touch sensing can also help robots avoid obstacles and locate objects in difficult environments. “Artificial skin must be able to cover large, irregular surfaces on the robot, have adequate sensitivity and dynamic range–all highly significant challenges that these new technologies promise to address,” says Ciocarlie.
The new electronic-skin devices “are a considerable advance in the state of the art in terms of power consumption and sensitivity,” says John Boland, professor of chemistry at Trinity College at the University of Dublin. “The real advance, though, is moving away from a flat geometry to a flexible device that could be used to make something in the shape of a human finger,” he says.
Surgical tools tipped with very sensitive tactile sensors could give doctors better control over how much force they use during minimally invasive surgeries. And large-area, flexible electronic skin could conform to the curves of future prosthetic devices. “Today’s prosthetics are crude–they can grasp but provide no tactile feedback,” notes Boland.