Physical Review Letters

Microscale Hydrodynamic Cloaking and Shielding via Electro-Osmosis

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We demonstrate theoretically and experimentally that injection of momentum in a region surrounding an object in microscale flow can yield both "cloaking"conditions, where the flow field outside the cloaking region is unaffected by the object, and "shielding"conditions, where the hydrodynamic forces on the object are eliminated. Using field-effect electro-osmosis as a mechanism for injection of momentum, we present a theoretical framework and analytical solutions for a range of geometrical shapes, validate these both numerically and experimentally, and demonstrate the ability to dynamically switch between the different states.