A Motor That Looks More Like Thread Than Machinery
Engineers at EPFL in Switzerland have built a flexible motor that looks like a thread, a form factor that sits at odds with almost everything the word "motor" normally brings to mind. The device, which the team calls FiberMotor, is flexible rather than stiff, and it extends in a way that resembles the sliding sections of a telescope. The intent behind the design is to power soft robots and wearables, two categories of technology that have long been held back by the rigid, boxy drives that sit at their core.
The pitch is simple to state and difficult to engineer: if the machine being built is soft, the thing that moves it should not be the hardest object in the assembly. FiberMotor is an attempt to close that gap by starting with the actuator itself rather than treating flexibility as an afterthought applied around conventional hardware.
Why Soft Robots Keep Running Into Hard Motors
Soft robotics has spent years developing bodies that bend, stretch, grip delicate objects and absorb impacts without shattering. The materials side of the field has moved quickly, with elastomers, fabrics and compliant structures that can twist and flex in ways metal linkages cannot. The problem arrives at the moment of actuation. Motors, gearboxes and the transmission lines that connect them are typically rigid, and bolting them onto a pliable body creates a mechanical mismatch.
That mismatch shows up in several practical ways:
- The rigid components become the heaviest and most brittle part of a supposedly soft system, limiting how compliant the whole machine can really be.
- Weight concentrates at the joints where the motor sits, which constrains the shapes a designer can build and the motions the device can perform safely.
- Interfaces between stiff hardware and soft material become wear points, the places where a device is most likely to fatigue or fail.
- Bulk limits how closely a soft robot can imitate a biological limb, which typically has distributed muscle rather than a single dense drive.
A motor that is itself flexible and thread-like addresses that mismatch at the source. Instead of designing around a rigid block, engineers would be working with an actuator that can be routed, bent and integrated into a pliable structure much as a tendon or cable might be.
The Telescope Behavior, Explained in Plain Terms
The comparison the researchers reach for is a telescope, and the analogy is about how the device changes length. A telescope extends by sliding nested segments past one another, gaining reach without gaining a single rigid body of that full length. FiberMotor is described as sliding in a comparable fashion, which suggests a mechanism that can telescope outward from a compact, flexible form rather than relying on a conventional shaft or rotor.
That matters for motion design. Telescoping extension gives a soft system a way to reach, push or lengthen along an axis while the actuator itself remains pliant. For robots that need to extend into confined spaces, or for wearable devices that must follow the contours of a moving body, an actuator that changes length on demand without imposing a stiff spine is a meaningfully different building block than a motor paired with a rigid lead screw.
Wearables Are the Second Half of the Bet
Wearable technology has a parallel problem. Devices worn on the body are judged on comfort, weight and how little they interfere with natural movement, yet powered assistive wearables have traditionally been built from rigid frames and motors that sit conspicuously on the hip, knee or back. Clothing-adjacent robotics, in contrast, would need drives that can be woven into fabric or laid along a limb without creating a pressure point or a hard edge.
A thread-like motor fits that brief conceptually. Textile manufacturing already handles flexible, elongated materials at scale, so an actuator shaped like a filament is at least compatible with the way garments are made. The same properties that would make FiberMotor useful in a soft robot — flexibility, a slim profile, the ability to extend along its own length — are the properties a wearable drive would need.
What Has Not Been Established Yet
An early-stage device announcement leaves the engineering questions open. EPFL's FiberMotor is presented as a flexible motor that resembles a thread and extends telescopically for soft robotics and wearables, but the headline description does not settle how much force such a motor can produce, how efficiently it converts energy into motion, how many cycles it can survive before the flexible elements degrade, or how it is powered and controlled in a real system.
Those are the numbers that determine whether a clever actuator becomes a practical component. Soft actuators often trade force density and precision for compliance, and the interesting question for FiberMotor is where it lands on that trade-off. A wearable that assists a joint, for instance, needs enough force to matter, while a soft robot manipulating fragile objects needs fine control. Whether a telescoping thread-like motor can deliver either at useful levels is the next thing to look for.
A Familiar Pattern in Actuator Research
FiberMotor sits inside a broader push to make actuation match the softness of the structures it drives. Research groups across Europe, Asia and North America have experimented with artificial muscles, cable-driven tendons, pneumatic chambers and electrostatic actuators, all pursuing the same goal from different angles: moving compliant machines with compliant hardware. EPFL's contribution adds a fiber-shaped, telescoping option to that menu.
The value of a new actuator category is rarely that it replaces existing motors outright. It is that it opens design space. If a motor can be as thin and flexible as thread, then robot limbs, exosuits and wearable aids no longer have to be organized around a rigid drive at a joint. They can be organized around distributed, textile-compatible actuation — closer to how biological muscle is arranged.
For now, FiberMotor is a promising shape rather than a proven product. The thread slides, the telescope extends, and the applications named are soft robots and wearables. The work ahead is the unglamorous part: measuring durability, output and control, then showing the device behaving reliably inside an actual machine.
This article is based on reporting by Interesting Engineering. Read the original article.
Originally published on interestingengineering.com
