Electronic Whiskers Could Help Robots Feel Their Surroundings
January 22, 2014

Nanotechnology Advance: Electronic Whiskers For Robotics

[ Watch the Video: Cats Inspire Nanotechnology Whiskers For Robotics ]

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Nanotechnology has brought us many advances such as electronic skin (e-skin) and electronic eye implants (e-eyes), and now, a research team from Berkeley Lab and the University of California Berkeley is on the verge of creating electronic whiskers.

The study, published in Proceedings of the National Academy of Sciences, describes the tactile sensors the team has created from composite films of carbon nanotubes and silver nanoparticles — similar to the highly sensitive whiskers of cats and rats. The pressure of a single Pascal — equivalent to the pressure exerted on a table surface by a dollar bill — can be felt by the new e-whiskers. The researchers see many potential applications, including giving robots new abilities to "see" and "feel" their surrounding environment.

“Whiskers are hair-like tactile sensors used by certain mammals and insects to monitor wind and navigate around obstacles in tight spaces,” Ali Javey, a faculty scientist in Berkeley Lab’s Materials Sciences Division and a UC Berkeley professor of electrical engineering and computer science, told Berkeley Lab's Lynn Yarris. “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.”

Javey and his team are leaders in the electronic skin development, along with other flexible electronic devices that interface with the environment. In making the whiskers, the team used a carbon nanotube paste to form an electrically conductive network matrix. This was loaded with a thin film of silver nanoparticles that endowed the matrix with 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 in a statement. “The composite can then be painted or printed onto high-aspect-ratio elastic fibers to form e-whiskers that can be integrated with different user-interactive systems.”

According to Javey, using elastic fibers with a small spring constant as the structural component of the whiskers provided large deflection. This caused high strain in response to the smallest applied pressures. To demonstrate proof-of-concept, the research team successfully used their e-whiskers to create highly accurate 2D and 3D mapping of wind flow. E-whiskers could be used in the future to mediate tactile sensing for the spatial mapping of nearby objects. This could also lead to wearable sensors for measuring heartbeat and pulse rate.

“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.”

Image 2 (below): An array of seven vertically placed e-whiskers was used for 3D mapping of the wind by Ali Javey and his group. Credit: Ali Javey/Berkeley Lab