Microscopic Robots Aid Medical Diagnostics

Using novel nanofabrication techniques, researchers have built micro-robots from silicon powered by solar cells. A 4-in. silicon wafer can help produce one million functional microscopic robots.

The robots’ bodies form from a superthin rectangular skeleton of glass topped with a thin layer of silicon, into which the researchers have etched electronics control components and either two or four silicon solar cells. Each robot’s four legs form from platinum and titanium bilayer (or graphene). The platinum is applied using atomic layer deposition. The platinum-titanium layer is then cut into each leg. The researchers shined a laser on the solar cells to power the microscopic robots.

That causes the platinum in the leg to expand while the titanium remains rigid, causing the limb to bend. Each solar cell causes the alternate contraction or relaxing of the front or back legs. It generates the robot’s gait. The legs of the microscopic robots impose low power requirements yet can carry loads ten thousand times their weight. Actuation only requires 200 mV signals, facilitating straightforward integration with silicon microelectronics.

The cell-sized microscopic robots can explore their environment, be manufactured en masse, and carry the full power of silicon-based information technology. They can survive harsh environments and are tiny enough to be injected through a hypodermic needle.

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