When researchers boast rather casually that making new variations of their invention is as simple as editing a CAD file, we might assume they are talking about a new sort of coffee mug, or perhaps a revolutionary spool for garden hose. Certainly such a simple and cost-effective design process could never give rise to something as complex as a bio-robot, a chimera of industrial gel and living tissue designed work inside the human body. However, after researchers at the University of Illinois set themselves the task of creating just such a robot, that’s precisely what they did.

Using new, specialized 3D printing technology, engineers were able to deposit a bio-friendly hydrogel into a cantilever design just seven by two millimeters in size, seeded with heart cells from a rat. The cells grew into a matrix and began doing what heart cells do best — beating. By depositing the cells in a particular arrangement throughout the structure, and coaxing them to grow in the desired ways, the beats eventually produced controlled forward movement. After a number of false starts and inferior designs, the researchers were able to build a bio-robot that moved consistently — albeit at only 236 micrometers per second, or 0.00053 miles per hour.

Theik workflow allowed the team to create an array of prototypes that they used determine the optimal length and thickness of the biobot’s actuating leg, which provides the power to drive the whole thing forward. In under a dozen prototypes, both CAD-designed and machine-printed, researchers found a working midpoint between the flexibility and strength of the actuating leg, as well as between the stability and size of the support leg.

To put this in perspective, previous attempts at making biological machines have required poured molds or even hand-cut sculptures, and their labor-intensive nature has not allowed the sort of trial and error engineering that has proven so powerful in other industries. Though the result is undeniably simple, it is a working proof of concept for not just biobots, but for bio-printing as well.

Uses for their hydrogel walker are purely speculative at this point, but the team sees potential for the robot to follow a toxin up its concentration gradient toward its source, where antitoxins could be released. In fact, some form of biobot is almost certain to be a large part of the burgeoning field of artificial immune systems. Additionally, while the robot might be small from our perspective, future designs could be plenty strong enough to carry payloads of everything from cell cultures to tracking devices. A tracked biobot released into the gut might stall at a hard-to-find blockage, thus showing physicians where it lies.

Of course, all of these applications are dependent on improving both the speed and lifespan of the biobot. Current designs lose most of their motility after just five days, and while finite lifespan and biodegradable contents are desirable attributes in almost anything released into the body, most jobs will require a more robust robot than that.

Already, the team is working to replace their heart muscle cells with skeletal muscles cells, which are harder to grow but both stronger and easier to control. Integration of specialized neurons should allow some form of sensing of the environment, and a two-legged version would allow more sophisticated steering and locomotion.

These may seem like daunting tasks, but the new approach to design makes even large problems surmountable. When the design process can be iterated in only a few days (and most of that time is spent just letting the cells grow), there’s no telling how soon these biobots might be sliding their way into through bodies, and past our expectations.

Now read: MIT creates biobattery that could allow the human ear to power its own hearing aid

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