A robot that drinks power from the floor it walks on

The tiniest robots have a big problem: batteries. A crawling robot weighing just 1.7 grams runs out of juice in about two minutes — and shrinking the battery only makes things worse. Yue Gao's team at Fudan University in Shanghai flipped the problem: what if the robot harvested energy from the ground itself? Their ‘skin’ — a thin membrane fitted to the robot's foot — triggers a chemical reaction on contact with metal surfaces like zinc and aluminum, turning each step into electricity using moisture from the air. The work, published in the peer-reviewed National Science Review, powered more than 10,000 walking steps, stayed stable after a million, and delivers about ten times the power density of a typical microbattery — from minus 20°C to 80°C.