Woven Micro Pumps for Wearable Fluid Technology

Switzerland-based engineers create micro pumps that can circulate fluid using electrohydrodynamics instead of mechanical pumps and be woven directly into fabric.

Circulating fluid through tubes woven into a garment was used successfully during the Apollo moon landings to regulate the astronauts’ body temperature. A new development by researchers at Switzerland-based École Polytechnique Fédérale de Lausanne has resulted in miniature tube pumps in the form of fibers that allow high-pressure fluidic circuits to be woven into textiles without an external pump. Pressure and flow are created by electrohydrodynamics, propelling ions in a special dielectric fluid. No external mechanical pump is needed, so the system could be used to create advanced devices for simulation, or potentially as an assistive exoskeleton.

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Episode Transcript:

In the days of the Apollo moon landings, the extreme environmental conditions of the moon’s surface combined with the airtight nature of the pressure suits needed in the vacuum of space meant that spacesuit engineers had a problem: keeping astronauts cool. 

The solution was to circulate fluid through a network of tubes sewn into an undergarment and then reject the heat through a heat exchanger. But what if fluids could be harnessed in this application for more than just temperature control? 

Research at the Switzerland-based École Polytechnique Fédérale de Lausanne has resulted in miniature pumps in the form of fibers that allow high-pressure fluidic circuits to be woven into textiles without an external pump. Integrating the tubing into the fabric at the microscale level suggests interesting possibilities in supportive exoskeletons, thermal clothing, and immersive haptics. 

Previous systems required an external pump, which was too large, bulky, and expensive to integrate directly into clothing. Researchers at the Soft Transducers Laboratory in the school of engineering at EPFL developed these fiber pumps using power created by charge injection electrohydrodynamics. Two helical electrodes embedded in the microscopic tubing walls ionize and accelerate molecules of a special dielectric fluid. By carefully shaping the electrodes, charges can propel ion movements to generate fluid flow without a mechanical pump. 

The EHD system operates silently, with no vibration, and can be powered with a pocket-sized power supply and battery. Careful control of the flow in the network of tubes inside a garment could assist in muscle movement, heating or cooling the body, and importantly, selectively compress areas of the garment. Integrated into gloves, for example, this ability to apply pressure could create the ultimate force feedback simulation for virtual and augmented reality systems in industries such as aviation and gaming. 

The 2 mm fibers are fabricated with a novel technique: polyurethane threads and copper wires are wound around a steel rod, a sort of mandrel, and then fused together into a tube. The fiber pumps are on the scale of conventional textile fibers and can be sewn and woven using standard, existing textile production technology. 

In the future, your jacket may not only keep you warm but might also help you lift heavy objects or give you the sensation of G-forces in a flight simulator.

Written by

James Anderton

Jim Anderton is the Director of Content for ENGINEERING.com. Mr. Anderton was formerly editor of Canadian Metalworking Magazine and has contributed to a wide range of print and on-line publications, including Design Engineering, Canadian Plastics, Service Station and Garage Management, Autovision, and the National Post. He also brings prior industry experience in quality and part design for a Tier One automotive supplier.