Tiny floating robots could be useful in all kinds of ways, for example, to probe the human gut for disease or to search the environment for pollutants. In a step toward such devices, researchers describe a new marriage of materials, combining ultrathin 2-D electronics with miniature particles to create microscopic machines.

The researchers will present their work today at the 255th National Meeting & Exposition of the American Chemical Society (ACS). ACS, the world’s largest scientific society, is holding the meeting here through Thursday. It features more than 13,000 presentations on a wide range of science topics.

“You can make electronic circuits that are a single atom thick, which is just insanely thin,” Michael Strano, Ph.D., says. “One creative use no one has thought of until now is taking these electronics and grafting them onto a colloidal particle. The particle, which can float in the air like a speck of dust, has simple computing functions. You can bring these new electronics to environments they otherwise could not access.”

As a first step, the researchers needed to develop a compatible set of electronic components for the particle’s coating to form a closed autonomous circuit. “This was difficult to do,” says Volodymyr Koman, Ph.D., a research fellow in Strano’s group at Massachusetts Institute of Technology. “We went through a number of different devices to meet certain power and energy requirements.”

In the end, Strano’s team selected a biocompatible material, SU-8, for the micrometer-sized particles and lithographically etched them to create a closed circuit consisting of a power source, a detector and a memory device. The power source was a p-n heterojunction of MoS2 and WSe2 that can convert light into electric current. Both MoS2 and WSe2 are 2-D semiconductors. The detector was a chemiresistor, a distinct single layer of MoS2, designed to change its electrical resistance in response to an environmental agent. The electrical output is stored in a memory device consisting of a separate layer of MoS2 flakes sandwiched between gold and silver electrodes.

Read more at NANOWERK.com

Image Credit:  Michael Strano

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