Move over, robots. Researchers at the University of Illinois are working on a different kind of miniaturized locomotive walking machines, ones made from hydrogels and neonatal rat heart cells; what the team affectionately refers to as "bio-bots." According to a new article in Nature, the scientists used lasers to carve a 3D print in a photosensitive pre-polymer solution, laying down the 2mm by 4mm bots’ scaffolding, then added a sheet of spontaneously-contracting heart cells. The result is that twice every three seconds a muscular sheet pumps the bot's cantilevered "actuator leg," pushing it around like a tiny skateboarder (video) through a liquid medium. After experimenting with a few different designs, the team managed to reach a top speed of 236 micrometers per second — about twice the width of an average human hair.

Forward-engineered from scratch

Unlike you might expect, the bots were forward-engineered from scratch. Rather than model them on structures and mechanisms found in nature, the scientists engineered their own solution "with desired geometry, mechanics, and cell adhesion molecules for optimal and robust locomotion." Thankfully, there’s no need to worry about being overrun by swarms of tiny meat-bots at this early stage. Setting aside the fact that the bots are only viable in a liquid medium, the scientists say that the cells only perform optimally for three to five days before the muscle loses its contractive force. So unless you're within 100 yards or so of ground zero, you're pretty much safe.

One of many practical applications for the bio-bots could be using them to track down chemical toxins and release a neutralizing agent. The team admits that a lot of work would need to be done for something like this to be possible (the bots would need to be smart), but in the long run it thinks the technology could transform areas like biosensing, drug delivery, energy production, environmental remediation, and the development of artificial immune systems.