Increasing the power density of electrohydrodynamic pumps by mapping the fluid landscape

Electrohydrodynamic (EHD) pumps noiselessly generate fluid flow in dielectric liquids using high electric fields to create, accelerate, and neutralize ions. Such pumps find applications in wearable actuators, soft robotics, and active thermal management. The influence of fluid properties on pressure and flow rate remains poorly understood. We present a systematic comparison of EHD pumping across 11 fluids, including 8 previously unidentified candidates, spanning viscosities from 0.5 to 19 millipascal seconds and dielectric constants from 2.3 to 64. Tests with more than 30 flexible fiber pumps show that low-viscosity and high-dielectric constant liquids markedly enhance pumping performance. For 1.2-millimeter-inner-diameter fiber pumps, replacing the commonly used Novec 7100 with propylene carbonate increased fluidic power density fivefold, reaching 495 milliwatts per cubic centimeter at 4.4 kilovolts. This study identifies key fluid properties for pumping, expands the EHD fluid library, and establishes a rigorous benchmark for performance evaluation, providing guidance for future EHD pump designs.