While humanoid robots made of plastic and metal dominate the news and capture the public’s interest, companies and universities are already researching the next generation of robots: after rigid robots come soft robots.

The most prominent representative of soft robots is the Polish company Clone Robotics, whose humanoids mimic human muscles using more than 200 tubes. The key components are tubes braided with a wire mesh that contract when a gas or liquid is injected into them, enabling them to perform complex movements.

This type of “muscle” is known as a pneumatic artificial muscle, also known as a McKibben muscle. Electrofluidic fiber muscles (EFM), a new class of artificial muscle fibers, utilize the same principle, but in a miniaturized version with a diameter of only one to two millimeters, and without external compressors or gas or liquid reservoirs.

EFMs, which directly integrate electrohydrodynamic (EHD) fiber pumps with charge injection into the muscular system, operate silently and wirelessly, eliminating the need for bulky external devices such as pumps, compressors, and hoses that have previously limited the mobility and practical application of soft robots. Fiber pumps consist of flexible and stretchable plastic tubing wrapped with wires that, without moving parts or vibrations and with minimal energy consumption, ionize and accelerate a dielectric fluid using high voltage by applying an electric charge, thereby generating pressure.

When applied to the McKibben muscle principle, the fibers can be alternately contracted and relaxed. This allows them to lift weights and move objects. If they are arranged like tendons and muscles on a humanoid robot, they can replace the heavy actuators commonly used today.

But these EFM devices aren’t limited to robotics. They could also be woven into clothing to, for example, adjust to the body’s shape or act like a body-hugging exoskeleton to assist with carrying or walking. These functions are noisy and heavy with today’s standard compressors or pumps, making them impractical. People with mobility impairments could gain greater freedom of movement without today’s bulky exoskeletons, as these EFM units could be sewn almost invisibly into their clothing.

This work was featured in the May 2026 issue of Science Robotics.