Tag Archives: Zhibin Yu

Get yourself some e-whiskers for improved tactile sensing

E-whiskers are highly responsive tactile sensor networks made from carbon nanotubes and silver nanoparticles that resemble the whiskers of cats and other mammals. Courtesy: Berkeley Labs [downloaded from http://newscenter.lbl.gov/science-shorts/2014/01/20/e-whiskers/]

E-whiskers are highly responsive tactile sensor networks made from carbon nanotubes and silver nanoparticles that resemble the whiskers of cats and other mammals. Courtesy: Berkeley Labs [downloaded from http://newscenter.lbl.gov/science-shorts/2014/01/20/e-whiskers/]

A Jan. 21, 2014 news item on Azonano features work from researchers who have simulated the sensitivity of cat’s and rat’s whiskers by creating e-whiskers,

Researchers with Berkeley Lab and the University of California (UC) Berkeley have created tactile sensors from composite films of carbon nanotubes and silver nanoparticles similar to the highly sensitive whiskers of cats and rats. These new e-whiskers respond to pressure as slight as a single Pascal, about the pressure exerted on a table surface by a dollar bill. Among their many potential applications is giving robots new abilities to “see” and “feel” their surrounding environment.

The Jan. 20, 2014 Lawrence Berkeley National Laboratory (Berkeley Lab) ‘science short’ by Lynn Yarris, which originated the news item,  provides more information about the research,

“Whiskers are hair-like tactile sensors used by certain mammals and insects to monitor wind and navigate around obstacles in tight spaces,” says the leader of this research Ali Javey, a 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.”

Javey and his research group have been leaders in the development of e-skin and other flexible electronic devices that can interface with the environment. In this latest effort, they used a carbon nanotube paste to form an electrically conductive network matrix with excellent bendability. To this carbon nanotube matrix they loaded 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 says. “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.”

Javey notes that the use of elastic fibers with a small spring constant as the structural component of the whiskers provides large deflection and therefore high strain in response to the smallest applied pressures. As proof-of-concept, he and his research group successfully used their e-whiskers to demonstrate highly accurate 2D and 3D mapping of wind flow. In the future, e-whiskers could be used to mediate tactile sensing for the spatial mapping of nearby objects, and 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 says. “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.”

The researchers’ paper has been published in the Proceedings of the National Academy of Sciences and is titled: “Highly sensitive electronic whiskers based on patterned carbon nanotube and silver nanoparticle composite films.”

Here’s what the e-whiskers look like,

An array of seven vertically placed e-whiskers was used for 3D mapping of the wind by Ali Javey and his group [ Kuniharu Takei, Zhibin Yu, Maxwell Zheng, Hiroki Ota and Toshitake Takahashi].  Courtesy: Berkeley Lab

An array of seven vertically placed e-whiskers was used for 3D mapping of the wind by Ali Javey and his group [ Kuniharu Takei, Zhibin Yu, Maxwell Zheng, Hiroki Ota and Toshitake Takahashi]. Courtesy: Berkeley Lab

Smart ‘curtains’ from the University of California at Berkeley

There’s a weirdly fascinating video that accompanies this research into light-activation and carbon nanotubes,

A Jan. 10, 2014 news item on Nanowerk provides an explanation,

A research team led by Ali Javey, associate professor of electrical engineering and computer sciences [University of California at Berkeley], layered carbon nanotubes – atom-thick rolls of carbon – onto a plastic polycarbonate membrane to create a material that moves quickly in response to light. Within fractions of a second, the nanotubes absorb light, convert it into heat and transfer the heat to the polycarbonate membrane’s surface. The plastic expands in response to the heat, while the nanotube layer does not, causing the two-layered material to bend.

The Jan. 9, 2014 University of California at Berkeley research brief by Sarah Yang, which originated the news item, provides some perspective from lead researcher Javey and a few more details about the research,

“The advantages of this new class of photo-reactive actuator is that it is very easy to make, and it is very sensitive to low-intensity light,” said Javey, who is also a faculty scientist at the Lawrence Berkeley National Lab. “The light from a flashlight is enough to generate a response.”

The researchers described their experiments in a paper published this week in the journal Nature Communications. They were able to tweak the size and chirality – referring to the left or right direction of twist – of the nanotubes to make the material react to different wavelengths of light. The swaths of material they created, dubbed “smart curtains,” could bend or straighten in response to the flick of a light switch.

“We envision these in future smart, energy-efficient buildings,” said Javey. “Curtains made of this material could automatically open or close during the day.”  [emphasis mine]

Other potential applications include light-driven motors and robotics that move toward or away from light, the researchers said.

Here’s a link to and a citation for the paper,

Photoactuators and motors based on carbon nanotubes with selective chirality distributions by Xiaobo Zhang, Zhibin Yu, Chuan Wang, David Zarrouk, Jung-Woo Ted Seo, Jim C. Cheng, Austin D. Buchan, Kuniharu Takei, Yang Zhao, Joel W. Ager, Junjun Zhang, Mark Hettick, Mark C. Hersam, Albert P. Pisano, Ronald S. Fearing, & Ali Javey. Nature Communications 5, Article number: 2983 doi:10.1038/ncomms3983 Published 07 January 2014

The earlier reference to energy-efficient buildings suggests that this work with light-activated curtains is another variation of a ‘smart’ window’ and bears some resemblance to Boris Lamontagne’s (Canada National Research Council) work with curling electrodes which act as blinds in his version of smart glass as per my .Sept. 16, 2011 posting.

Ali Javey has been mentioned here before in a Sept. 15, 2010 post concerning nanotechnology-enabled robot skin.