In a world where "supersize" has entered the lexicon, thereare some things getting smaller, like cell phones and laptops.Dartmouth researchers have contributed to the miniaturizing trend bycreating the world's smallest untethered, controllable robot. Theirextremely tiny machine is about as wide as a strand of human hair, andhalf the length of the period at the end of this sentence. About 200 ofthese could march in a line across the top of a plain M&M.
Theresearchers, led by Bruce Donald, the Joan P. and Edward J. Foley Jr.1933 Professor of Computer Science at Dartmouth, report their creationin a paper that will be presented at the 12th International Symposiumof Robotics Research in October in San Francisco, which is sponsored bythe International Federation of Robotics Research. A longer, moredetailed paper about this microrobot will also appear in a forthcomingissue of the Journal of Microelectromechanical Systems, a publicationof the IEEE, the Institute of Electrical and Electronics Engineers.
"It'stens of times smaller in length, and thousands of times smaller in massthan previous untethered microrobots that are controllable," saysDonald. "When we say 'controllable,' it means it's like a car; you cansteer it anywhere on a flat surface, and drive it wherever you want togo. It doesn't drive on wheels, but crawls like a silicon inchworm,making tens of thousands of 10-nanometer steps every second. It turnsby putting a silicon 'foot' out and pivoting like a motorcyclistskidding around a tight turn."
The future applications formicro-electromechanical systems, or MEMS, include ensuring informationsecurity, such as assisting with network authentication andauthorization; inspecting and making repairs to an integrated circuit;exploring hazardous environments, perhaps after a hazardous chemicalexplosion; or involving biotechnology, say to manipulate cells ortissues.
Donald worked with Christopher Levey, AssistantProfessor of Engineering and the Director of the MicroengineeringLaboratory at Dartmouth's Thayer School of Engineering, Dartmouth Ph.D.students Craig McGray and Igor Paprotny, and Daniela Rus, AssociateProfessor of Electrical Engineering and Computer Science at theMassachusetts Institute of Technology.
Their paper describes amachine that measures 60 micrometers by 250 micrometers (one micrometeris one thousandth of a millimeter). It integrates power delivery,locomotion, communication, and a controllable steering system - thecombination of which has never been achieved before in a machine thissmall. Donald explains that this discovery ushers in a new generationof even tinier microrobots.
McGray, who earned a Ph.D. inComputer Science working on this project in Donald's lab, adds,"Machines this small tend to stick to everything they touch, the waythe sand sticks to your feet after a day at the beach. So we builtthese microrobots without any wheels or hinged joints, which must slidesmoothly on their bearings. Instead, these robots move by bending theirbodies like caterpillars. At very small scales, this machine issurprisingly fast." McGray is currently a researcher at the NationalInstitute of Standards and Technology in Gaithersburg, Md.
Theprototype is steerable and untethered, meaning that it can move freelyon a surface without the wires or rails that constrained the motion ofpreviously developed microrobots. Donald explains that this is thesmallest robot that transduces force, is untethered, and is engaged inits own locomotion. The robot contains two independent microactuators,one for forward motion and one for turning. It's not pre-programmed tomove; it is teleoperated, powered by the grid of electrodes it walkson. The charge in the electrodes not only provides power, it alsosupplies the robot's instructions that allow it to move freely over theelectrodes, unattached to them.
The work was funded in part bythe Department of Homeland Security, Office of Domestic Preparednessthrough Dartmouth's Institute for Security Technology Studies (ISTS).
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