Soft Robots with No Strings Attached

There is a big reason why so many soft robots have been described in the scientific literature, yet so few commercial platforms exist. On the surface, these robots might look good, but when you dig into the details, you will commonly find that they are tethered to external systems for actuation and control, greatly limiting their real-world practicality. If robots such as these are meant for searching through piles of rubble after a disaster, for instance, the tubes and wires that give them life will prevent them from going very far.

A more practical soft robot design has recently been proposed by engineers at Penn State University. They have developed a tiny, flexible robot that has all of the processing power and sensors that it needs to autonomously do its job right onboard. No physical connections to external systems are needed for control or actuation, although it does rely on external magnetic fields for the latter, so it cannot venture too far from home base.

To add intelligence to the robot, the team distributed electronic components across the flexible structure that makes up the robot’s body to avoid compromising its movement. Even though the electronics are designed to be bendable, they are still significantly stiffer than the soft material that makes up the body. But careful placement of the electronics preserved the robot’s flexibility while ensuring it could perform complex tasks, like detecting heat, pressure, or chemical changes.

The robot’s motion is powered by magnetic materials embedded in its body. When exposed to an external magnetic field, the robot can perform a range of movements — crawling, bending, spinning — without needing internal motors or a power supply. This magnetic actuation also eliminates the need for wired connections that would typically limit mobility.

One significant hurdle the team faced was magnetic interference. Since the robot’s movement depends on external magnetic fields, those same fields can disrupt the sensitive electronics onboard — particularly the sensors responsible for detecting environmental changes. To address this, the researchers carefully designed the layout of the electronic components to shield them from interference and ensure reliable performance. By minimizing electromagnetic crosstalk and strategically isolating circuits from magnetic hotspots, they preserved the integrity of the robot’s sensing capabilities even while it was in motion.

A particularly promising application of this technology is in medicine. The researchers are working on miniaturizing the design into a “robot pill” that can be swallowed, navigate through the gastrointestinal tract, and deliver drugs or gather diagnostic data in real time. The goal is to provide a less invasive and more precise alternative to traditional diagnostic tools. Future versions, if small enough, could even be injected into blood vessels for targeted cardiovascular treatments.

This solution may not be right for every use case, but the integration of soft materials, electronics, and magnetic control may help to transform today’s lab-bound prototypes into soft robots that have value in real-world applications.