Engineers Make Artificial Skin out of Nanowires
ScienceDaily (Sep. 12, 2010) — Engineers at the University of California, Berkeley, have developed a pressure-sensitive electronic material from semiconductor nanowires that could one day give new meaning to the term "thin-skinned."
This is an artist's illustration of an artificial e-skin with nanowire active matrix circuitry covering a hand. A fragile egg is held, illustrating the functionality of the e-skin device for prosthetic and robotic applications. (Credit: Ali Javey and Kuniharu Takei)
"The idea is to have a material that functions like the human skin, which means incorporating the ability to feel and touch objects," said Ali Javey, associate professor of electrical engineering and computer sciences and head of the UC Berkeley research team developing the artificial skin.
The artificial skin, dubbed "e-skin" by the UC Berkeley researchers, is described in a Sept. 12 paper in the advanced online publication of the journal Nature Materials. It is the first such material made out of inorganic single crystalline semiconductors.
A touch-sensitive artificial skin would help overcome a key challenge in robotics: adapting the amount of force needed to hold and manipulate a wide range of objects.
"Humans generally know how to hold a fragile egg without breaking it," said Javey, who is also a member of the Berkeley Sensor and Actuator Center and a faculty scientist at the Lawrence Berkeley National Laboratory Materials Sciences Division. "If we ever wanted a robot that could unload the dishes, for instance, we'd want to make sure it doesn't break the wine glasses in the process. But we'd also want the robot to be able to grip a stock pot without dropping it."
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NATURE MATERIALS | LETTER
Nanowire active-matrix circuitry for low-voltage macroscale artificial skin
Kuniharu Takei, Toshitake Takahashi, Johnny C. Ho, Hyunhyub Ko, Andrew G. Gillies, Paul W. Leu, Ronald S. Fearing & Ali Javey
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Contributions
Corresponding authorNature Materials (2010) doi:10.1038/nmat2835Received 26 March 2010 Accepted 16 July 2010 Published online 12 September 2010
Large-scale integration of high-performance electronic components on mechanically flexible substrates may enable new applications in electronics, sensing and energy1, 2, 3, 4, 5, 6, 7, 8. Over the past several years, tremendous progress in the printing and transfer of single-crystalline, inorganic micro- and nanostructures on plastic substrates has been achieved through various process schemes5, 6, 7, 8, 9, 10. For instance, contact printing of parallel arrays of semiconductor nanowires (NWs) has been explored as a versatile route to enable fabrication of high-performance, bendable transistors and sensors11, 12,13, 14. However, truly macroscale integration of ordered NW circuitry has not yet been demonstrated, with the largest-scale active systems being of the order of 1 cm2 (refs 11,15). This limitation is in part due to assembly- and processing-related obstacles, although larger-scale integration has been demonstrated for randomly oriented NWs (ref. 16). Driven by this challenge, here we demonstrate macroscale (7×7 cm2) integration of parallel NW arrays as the active-matrix backplane of a flexible pressure-sensor array (18×19 pixels). The integrated sensor array effectively functions as an artificial electronic skin2, 17, 18, capable of monitoring applied pressure profiles with high spatial resolution. The active-matrix circuitry operates at a low operating voltage of less than 5 V and exhibits superb mechanical robustness and reliability, without performance degradation on bending to small radii of curvature (2.5 mm) for over 2,000 bending cycles. This work presents the largest integration of ordered NW-array active components, and demonstrates a model platform for future integration of nanomaterials for practical applications.
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