https://phys.org/news/2018-07-scientists-mimic-machine-machines.html

"This is a first important step in what we can build synthetically to emulate living systems," noted Palacci.

The building blocks are self-powered microparticles that propel after being activated by light. The scientists specially designed them to autonomously sense light gradients and navigate in light patterns. This leads to their remarkable assembly into only one type of machine—a self-forming, spinning microgear comprised of seven such microparticles—a "machine made of machines."