As nanotechnology, or the building of machines at the molecule scale, and biomimicry has progressed and advanced, electronic skin and even electronic eyes have been developed. Researchers with Berkeley Lab and the University of California (UC) Berkeley are developing electronic whiskers. Whiskers, used by some mammals, are tactile sensors that assist the animal in navigating around obstacles and small spaces. 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, says that their, “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.”
[i] The e-whiskers developed by Javey’s team can respond to pressure as slight as one Pascal, which is approximately equivalent to the pressure exerted on a table surface by a dollar bill. It is hoped that these e-whiskers will provide robots with an ability to not only see but feel their surrounding environment as well. Possible applications of e-whiskers could include using robots to explore underground, under the sea, or extremely dusty conditions where vision is impaired. A specific possible scenario could include searching a smoke filled room for survivors. E-whiskers could also be used for tactile inspection of surfaces in the textile industry.
Javey and his group have been some of the leading researchers in e-skin development. With this latest advancement they used a carbon nanotube paste to form an electrically conductive network matrix that had incredible bendability. Thin films of silver nanoparticles were added to the carbon nanotube to allow it to be extremely sensitive to mechanical strain. The strain sensitivity and electrical resistivity of the composite film can be adjusted by changing the composition ratio of the carbon nanotubes and the silver nanoparticles. To test their e-whiskers, Javey and his team placed several e-whiskers on an upturned dome. They then blew hydrogen gas over the whiskers. The whiskers were extremely accurate in creating 2D and 3D maps of the wind flow.
The idea of incorporating mammal like whiskers into technology is not a new one. In 2009 a group of scientists from the Bristol Robotics Lab (a partnership between the University of the West of England and the University of Bristol) and the University of Sheffield developed the SCRATCHbot, which used whiskers instead of cameras to see in visually impaired areas. The idea for this robot came from primarily nocturnal mammals that utilize their physical sense over vision. These mammals, such as rats, use their whiskers to determine shape, position, and texture of objects by using rhythmic sweeping movements. Dr. Tony Pipe, of Bristol Robotics Lab and the University of the West of England, has said, “For a long time, vision has been the biological sensory modality most studied by scientists. But active touch sensing is a key focus for those of us looking at biological systems which have implications for robotics research.”[ii]
A paper detailing the work of Javey’s team was recently published in the Proceedings of the National Academy of Sciences. It is titled “Highly sensitive electronic whiskers based on patterned carbon nanotube and silver nanoparticles composite films.” Javey is the corresponding author, and co-authors include Kuniharu Takei, Zhibin Yu, Maxwell Zheng, Hiroki Ota and Toshitake Takahashi.
While nature has always been difficult for scientists to mimic, the advances in biomimicy have come leaps and bounds. To view previous Glew Engineering blogs written on biomicry please click the links below.