How do you make a robot or other device sensitive to the world around it? Try looking at nature for an example. In the latest example of biomimicry, or science is inspired by nature, a team of researchers in California have turned to cats and other whiskered animals to develop a new technology that could make devices capable of interfacing with the environment. They call their discovery electronic whiskers – or e-whiskers for short.
"Whiskers are hair-like tactile sensors used by certain mammals and insects to monitor wind and navigate around obstacles in tight spaces," lead researcher Ali Javey of Berkeley Lab's Materials Sciences Division said in a news release. "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."
How sensitive were these e-whiskers? The researchers say they could detect pressure as low as a single pascal, a unit of pressure. By comparison, that's about the same pressure a dollar bill exerts against any surface it is laid upon. By further comparison, the standard atmospheric pressure here on Earth is more than 101 kilopascals. The researchers say this is at least 10 times more sensitive than any other previously developed resistive pressure sensors.
Details on the new e-whiskers were published last week in the Proceedings of the National Academy of Sciences. The researchers built a tiny half-globe with an array of seven e-whiskers at various points along its curve. They then let the wind flow over the array. The e-whiskers were able to gather enough information to map the flow of the wind in both 2-D and 3-D. Although the research is currently just at the "proof of concept" stage, the team says this could lead to the creation of incredibly sensitive spatial mapping devices or even wearable sensors that would measure things like heartbeat and pulse rate.
The e-whiskers were composed of what the paper describes as "highly tunable composite films of carbon nanotubes and silver nanoparticles that are patterned on high-aspect-ratio elastic fibers." The nanotubes provide both flexibility – allowing the whiskers to bend when they experience pressure – and conductivity – allowing them to transmit data on the environmental factors they experience.
Javey said the team's e-whiskers could lead to technologies for real-time monitoring of environmental factors. "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," he said.
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