Tools & manufacturing · December 2025

Salt-grain autonomous robots

Light-powered robots with onboard computers, a cent apiece.

Penn and Michigan engineers built autonomous robots 200 by 300 by 50 micrometers with onboard computing, powered by light and able to run for months at about one cent each.

See it in the living tree Wikipedia Source

Arcs above join it to what it stood on, arcs below to what it led to. The bar places this stretch on the tree's whole timeline.

What it built on 2

Microprocessor (Intel 4004) 1971
Silicon solar cell 1954

Related measurements

The dashed line marks when it first worked.

Transistors per microprocessor Latest: 58.2B transistors (2021) Source: Our World in Data