Fudan team's paper-thin foot pad lets crawling microrobots draw power from ground

Researchers at Fudan University have built a paper-thin membrane that lets crawling micro-robots draw power directly from the ground beneath them. The approach removes the need for heavy onboard batteries, a major constraint for tiny legged machines.

The membrane is only 135 micrometers thick and is grown directly onto the robot’s feet. When a foot touches a reactive surface such as aluminum, zinc, or silicon, the metal floor supplies electrons. The membrane simultaneously absorbs oxygen and moisture from the surrounding air to complete an electrochemical circuit.

Power begins flowing immediately upon contact and stops the instant the foot lifts. This contact-based harvesting turns each step into a brief burst of energy, avoiding continuous battery drain.

In tests, a 3D-printed crawling robot operated intermittently for 150 days. It exceeded 10,000 steps without any voltage drop, eventually crossing the million-step mark while consuming only about 2 grams of aluminum.

The result suggests that microrobots could sustain long missions by scavenging energy from their environment rather than carrying power supplies. The design could help untethered micro-robots operate in confined spaces for extended periods. The team says the foot membrane may offer a scalable route to autonomous crawling robots.