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transistor made up of hundreds of semiconductor nanowires. Nanowire transistors were then integrated with a pressure sensitive rubber on top to provide the sensing functionality. The matrix required less than 5 volts of power to operate and maintained its robustness after being subjected to more than 2,000 bending cycles.

The researchers demonstrated the ability of the e- skin to detect pressure from 0 to 15 kilopascals, a range comparable to the force used for such daily ac- tivities as typing on a keyboard or holding an object. In a nod to their home institution, the researchers successfully mapped out the letter C in Cal.

“This is the first truly macroscale integration of orde- red nanowire materials for a functional system – in this case, an electronic skin,” said study lead author Kuniharu Takei, post-doctoral fellow in electrical engineering and computer sciences. “It’s a technique that can be potentially scaled up. The limit now to the size of the e-skin we developed is the size of the processing tools we are using.”

Other UC Berkeley co-authors of the paper are Ron Fearing, professor of electrical engineering and com- puter sciences; Toshitake Takahashi, graduate stu- dent in electrical engineering and computer sciences; Johnny C. Ho, graduate student in materials science and engineering; Hyunhyub Ko and Paul Leu, post- doctoral researchers in electrical engineering and computer sciences; and Andrew G. Gillies, graduate student in mechanical engineering.

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right: An optical image of a fully fabricated e-skin device with nanowire active matrix circuitry. Each dark square repre- sents a single pixel. © Ali Javey and Kuniharu Takei, UC Berkeley

An artist’s illustra- tion of an artificial e-skin with nano- wire active matrix circuitry covering a hand. The fragile egg illustrates the functionality of the e-skin device for prosthetic and ro- botic applications. © Ali Javey and Kuniharu Takei, UC Berkeley

Kuniharu Takei, Toshitake Takahashi, Johnny C. Ho, Hyunhyub Ko, Andrew G. Gillies, Paul W. Leu, Ronald S. Fearing, Ali Javey: Nanowire active-matrix circuitry for low-voltage macroscale artificial skin, In: Nature Materi- als, Vol. 9(2010), No. 10, October 2010, Pages 821-826, DOI:10.1038/nmat2835: http://dx.doi.org/10.1038/nmat2835