Scientists at Berkeley Lab and the University of California (UC) Berkeley have created sensitive, tactile sensors that are similar to a cat's whiskers. The so-called "e-whiskers" could be used to help robots feel their way around a space.

As explained by Berkeley Lab’s Ali Javey, whiskers are used by certain animals to monitor wind and navigate around obstacles and spaces. The artificial whiskers created by Javey and his team respond to pressure as slight as that of a dollar bill resting on a table (about 1 Pa).

"Our electronic whiskers consist of high-aspect-ratio elastic fibers coated with conductive composite films of nanotubes and nanoparticles," says Javey. "In tests, these whiskers were 10 times more sensitive to pressure than all previously reported capacitive or resistive pressure sensors."

To create the e-whiskers, the researchers used a carbon nanotube paste to form a flexible, electrically-conductive network matrix. A thin film of silver nanoparticles was then added, making the matrix sensitive to mechanical strain. According to Javey, the sensitivity and electrical resistivity of the composite film can be changed by adjusting the ratio of carbon nanotubes to silver nanoparticles.

Once ready, the composite is painted or printed onto elastic fibers to form the e-whiskers. Adding the e-whiskers to a robot allows the robot to detect obstacles in the same way that a cat does, helping with decision about which direction to move.

Research team member Kuniharu Takei explained to Gizmag that the initial idea for e-whiskers was borne out of a request from a robotics researcher during the team's work on artificial electronic skin, some three years ago. At the time, there was no means of realizing the idea, but following the development of high sensitivity strain sensor materials, the concept was able to be taken forward.

The team has demonstrated e-whiskers by using them to produce 2D and 3D mapping of wind flow. Presently, only pressure information can be detected with the e-whisker, but the integration of more sensors and signal processing circuits would allow for other applications. The team is also keen to demonstrate macro-scale printing fabrication to lower the cost of production.

"Here we demonstrated the e-whisker by forming the strain sensor onto the e-whisker polymer structure," says Takei. "We think this demonstration is very important, not only for the e-whisker, but also for printed electronics. This technology can be also applied to many applications such as wearable electronics and some other flexible devices."

The Berkeley Lab research is not the only work of its kind. The four-year EU-funded BIOTACT project sought to replicate the sensory abilities of rat whiskers.

A research paper detailing the Berkeley team's work was recently published in the Proceedings of the National Academy of Sciences.

Source: Berkeley Lab

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