EPFL researchers have developed a fiber-like pump that allows high-pressure fluid circuits to be woven into textiles without an external pump.
Many of today’s fluid-based wearable assistive technologies require large, noisy pumps that are impractical, if not impossible, to integrate into clothing. This leads to contradictions. Wearable devices are routinely tethered to non-wearable pumps. Now, researchers at the Faculty of Engineering’s Soft He Transducer Laboratory (LMTS) have developed an elegant and simple solution to this dilemma.
“We present the world’s first pump in fiber form, essentially a tube that generates its own pressure and flow,” said Herbert Shea, Head of LMTS. “Now, Fiberhis pumps can be sewn directly onto textiles and clothing, leaving traditional pumps behind.”
This research was published in the journal Science.
Light, Powerful, Washable
Shea’s lab has a history of advanced fluidics. In 2019, we produced the world’s first telescopic pump.
“This study builds on the previous generation of soft pumps,” said Michael Smith, a postdoctoral researcher at LMTS and lead author of the study. “The fiber format allows us to create lighter, stronger pumps that are inherently more compatible with wearable technology.”
LMTS fiber pumps use a principle called charge injection electrohydrodynamics (EHD) to generate fluid flow without moving parts. Two helical electrodes embedded in the pump wall ionize and accelerate molecules in a special non-conducting liquid. Ion motion and electrode geometry create a net forward fluid flow for quiet, vibration-free operation, requiring only a palm-sized power supply and battery.
To achieve the pump’s unique construction, researchers developed a new manufacturing technique in which copper wires and polyurethane threads are twisted together around a steel rod and fused together with heat. After removing the rod, the 2 mm fibers can be incorporated into the textile using standard weaving and sewing techniques.
The simple design of the pump has many advantages. The materials needed are cheap and readily available, and the manufacturing process is easy to scale up. The amount of pressure generated by a pump is directly related to its length, so tubing can be cut to fit your application, optimizing performance while minimizing weight. The durable design can also be washed with regular detergent.
From exoskeletons to virtual reality
The authors have already shown how these fiber pumps can be used in new and exciting wearable technologies. For example, for people working in extreme temperature or therapeutic environments, hot and cold fluids can be circulated through clothing to help manage inflammation. For those who want to maximize athlete performance.
“Those applications just need long tubes, and in our case, the tubes are the pumps. This means we can create very simple, lightweight fluid circuits that are convenient and comfortable to wear.” says Smith.
The study also describes a fabric artificial muscle and an implanted fiber pump. It can be used to power a soft exoskeleton to help patients move and walk.
Pumps can even bring a new dimension to the world of virtual reality by simulating the sensation of temperature. In this case, the user can wear a glove with a pump filled with hot or cold liquid and feel the temperature change in response to contact with the virtual object.
excited for the future
Researchers are already trying to improve the device’s performance. “The pump is already performing well and we are confident that with further work we can continue to improve in areas such as efficiency and longevity,” says Smith. Work has already begun to scale up production of the fiber pumps, and LMTS also plans to incorporate them into more complex wearable devices.
“We believe this innovation will be a game changer for wearable technology,” says Shea.
Original: Thread-like pumps that can be woven into clothes
Than: Lausanne Federal Institute of Technology
