Researchers at the University of Pennsylvania and the University of Michigan have unveiled the world’s smallest robots. The work was published on 15 December in Science Robotics and PNAS.

These microscopic robots measure only 200 × 300 × 50 micrometres (smaller than a grain of salt), yet they can:

  • Sense temperature
  • Process information
  • Make decisions and move
  • Work non-stop for months

— all at a cost of about one cent per robot.

Solving a 40-year challenge

Marc Miskin, professor of electrical engineering at Penn, says: “We’ve made robots 10,000 times smaller. That means entering a completely new scale in robotics.”

Movement without mechanical parts

Unlike conventional robots, these have no moving parts and move by electrokinetic propulsion: by creating an electric field, they push surrounding ions, and this flow propels the robot through liquid.

The world’s smallest computers

The robots’ processor was developed by David Blaauw’s team at the University of Michigan:

  • Power consumption: only 75 nanowatts
  • About 100,000 times more efficient than a smartwatch
  • The lab holds the record for the world’s smallest computer

To fit a processor at this scale, the team had to completely redesign the programming language and compress several movement commands into a single special instruction.

Temperature sensing and smart communication

  • Temperature accuracy: to within a third of a degree Celsius
  • Data transmitted through movement patterns similar to a bee’s dance
  • Each robot has a unique address
  • Programming and power delivered via light pulses

Performance and durability

  • Speed: up to one body length per second
  • Capable of coordinated group movement
  • Able to work continuously for months
  • Resistant to repeated handling with a micropipette

Future applications

  • Monitoring the health of individual cells
  • Building microscopic medical machines
  • Developing smart systems at the cellular scale

Miskin concludes: “This is just the first chapter. We’ve shown you can fit a brain, sensors and a motor into something almost invisible and have it work for months.”