Tactile Sensors Look a Lot Like Cat Whiskers

A researcher at Berkeley Lab and the University of California (UC), Berkeley used carbon nanotube paste to form a bendable electrically conductive network matrix, which is claimed to look similar to cat and rat whiskers.

The "e-whiskers" were developed to respond to pressure and have the potential to give robots new mobile capabilities within surrounding environments.

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"Whiskers are hair-like tactile sensors used by certain mammals and insects to monitor wind and navigate around obstacles in tight spaces," said Ali Javey, research leader and faculty scientist in Berkeley Lab’s Materials Sciences division and a UC Berkeley professor of electrical engineering and computer science. "Our electronic whiskers consist of high-aspect-ratio elastic fibers coated with conductive composite films of nanotubes and nanoparticles. In tests, these whiskers were 10 times more sensitive to pressure than all previously reported capacitive or resistive pressure sensors."

After forming the carbon network matrix, Javey and his research group put the matrix into a thin film of silver nanoparticles, giving it high sensitivity to mechanical strain.

"‘The strain sensitivity and electrical resistivity of our composite film is readily tuned by changing the composition ratio of the carbon nanotubes and the silver nanoparticles," Javey said. "The composite can then be painted or printed onto high-aspect-ratio elastic fibres to form e-whiskers that can be integrated with different user-interactive systems."

Javey also notes that the combination of elastic fibers with a small spring constant that form the structure of the whiskers allows the components to respond to the smalles smallest pressures with high strain.

The e-whiskers were used to demonstrate 2D and 3D mapping of wind flow, and could be used in the future to mediate tactile sensing for the spatial mapping of nearby objects and later lead to wearable sensors for measuring heartbeat and pulse rate, according to Javey.

"Our e-whiskers represent a new type of highly responsive tactile sensor networks for real time monitoring of environmental effects," Javey said. "The ease of fabrication, light weight and excellent performance of our e-whiskers should have a wide range of applications for advanced robotics, human-machine user interfaces and biological applications."