Developments to watch: Mobile microrobots

Future robots much smaller than Lincoln’s smile on a penny may locate cancer cells, enter, and deliver anti-cancer agents, or self-assemble into a structure, providing science-fiction-like advances in medicine, manufacturing, and other industries. At present, power and control remain two significant challenges, according to Dr. Igor Paprotny, assistant professor, University of Illinois at Chicago, speaking at Sensors Expo on June 25.

By Mark T. Hoske July 2, 2014

Untethered mobile microscale robotic system research began in the 1980s and continues with a growing number of researchers involved, according to Dr. Igor Paprotny, assistant professor, University of Illinois at Chicago, speaking at Sensors Expo on June 25. Progress is slow as power and control remain significant hurdles, but the prospect of micro electrical mechanical systems (MEMS) microrobots has significant potential in manufacturing, biomedicine, and surveillance. And navigation is improving, he suggested.

Paprotny, discussing current trends and future directions in microrobots, also reviewed the progress of his team, showing images and an amusing video of moving microrobots set to the "Blue Danube" waltz, including a "docking" procedure where two link.

Disruptive technology

Microrobotics "will be disruptive technology," Paprotny said; applications include surveillance, imaging and sensing, assembly, biomedicine, and smart structures, as robots collaborate.

Microrobots, by definition, operate within a 1 mm cube. Autonomous flight is proven in the insect world within that size range, he noted, showing an image of a flying butterfly parasite about 130 microns in size that appeared as a speck on the head of a butterfly.

Motive force from substrate

Paprotny’s team’s "MicroStressBots" use a powered substrate for motion; they’re rectangular (160 x 60 microns) with a leg with a circle on the end adding 100 microns to one corner for 260 microns total. Movements are similar to those of an inchworm-scratch-drive propulsion, he called it. Dragging the arm can create a turn.

Challenges include:

  1. Fabrication integration of a complete system at a micro scale.
  2. Power; at present, off-board electrostatic power delivery is used.
  3. Control; off-board control is used; it’s a massively under-actuated system. At present, the robots only turn one way, although they can be made to turn with a tighter radius.

In a separate effort, a small flying robot also is under development. The microflyers, which appear like a small fan blade, 1.5 micron thick with a 300-micron wingspan, actually have a small jumping action traveling 126 microns. They use the same motive principle as a spinner solar radiometer. Paprotny acknowledged that eight students also working on this research.

Differing motive approaches are being used by other researchers, including magnetic forces (most common), biological (modified bacteria or sperm), or catalytic (with rolled-up tubules).

– Mark T. Hoske, content manager, CFE Media, Control Engineering, 

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Author Bio: Mark Hoske has been Control Engineering editor/content manager since 1994 and in a leadership role since 1999, covering all major areas: control systems, networking and information systems, control equipment and energy, and system integration, everything that comprises or facilitates the control loop. He has been writing about technology since 1987, writing professionally since 1982, and has a Bachelor of Science in Journalism degree from UW-Madison.