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A conceptual advance that gives microrobots legs

An exciting article appeared in Nature, 530-531 (2020); doi: 10.1038 / d41586-020-02421-2

Tiny devices have been developed that can act as the legs of laser-controlled microrobots. The compatibility of these devices with microelectronic systems suggests a route to mass production of autonomous microrobots.

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In 1959, Nobel laureate and nanotechnology visionary Richard Feynman suggested that it would be interesting to "swallow the surgeon" - that is, build a tiny robot that could move through blood vessels to perform surgery if necessary. This iconic vision of the future underscored the modern hopes in the field of micrometer robotics: to deploy autonomous devices in environments that their macroscopic counterparts cannot reach. However, building such robots presents several challenges, including the obvious difficulty of assembling a microscopic locomotive. In an article in Nature, Miskin et al. via electrochemically powered devices that propel laser-controlled microrobots through a liquid and that can be easily integrated with microelectronic components to create fully autonomous microrobots.

Developing propulsion strategies for microrobots moving through fluid environments is challenging as strong drag forces prevent microscopic objects from maintaining their momentum. To overcome this challenge, Miskin and his coworkers designed tiny actuators - devices that convert energy into motion - that fold and unfold when tiny amounts of electrical current are applied. The current causes ions from a surrounding solution to be adsorbed on the surface of the actuator, changing the tension in the leg and causing it to bend. The authors construct these actuators using the same nanofabrication techniques that are used in the manufacture of computer chips.

An interesting aspect of the work of Miskin and his colleagues is that they used a fresh design concept for their microrobots. Instead of adding a drive mechanism to a static particle, they miniaturized an archetypal robot: a walking machine whose mechanical legs are controlled by electronics. Since the actuators are constructed using the same techniques that are used in the manufacture of printed circuit boards, the "brains" (logic circuits) and the legs of future robots could in principle be printed at the same time. And since the actuators can be operated by the low power electrical currents that typically flow through electronic circuitry, sensors and logic components could be seamlessly integrated into the actuators.