Self-Pumping Tubing: Fiber-Format Electrohydrodynamics

Fiber-based devices are at the heart of wearables. We report here a fluidic pump in the form of a stretchable and flexible fiber, enabling the benefits of fluidic systems and associated soft actuators to be deployed in a wearable context. Our pumps consist of two continuous helical copper electrodes embedded within the walls of a 2 mm diameter polyurethane tube. The pumps generate pressure silently and without any moving parts using the principle of charge-injection electrohydrodynamics. The tubing itself becomes the pump, affording vast design freedom in the implementation of wearable fluidic circuits, which we illustrate with demonstrations of wearable haptics (glove), mechanically active fabric sheets and thermoregulatory textiles (shirt).<br/>The maximum pressure generated by each pump is proportional to its length, with each meter of fiber generating 100 kPa of pressure, or flowrates of 50 ml/min, at an applied electric field of 8 kV/mm. To function, the liquid being pumped must be a dielectric fluid with a high breakdown strength. Here, we use the dielectric fluid Novec 7100, a non-toxic, non-flammable methoxy-fluorocarbon. Judging by specific pressure and specific flowrate, the fiber-shaped pumps outperform by more than an order of magnitude the conventional miniature pumps that they replace. The scalability, simplicity and bi-directional pumping capabilities of these fiber pumps enables a wide range of wearable applications that are not possible with conventional pumping technologies.