We present the proof-of-concept for a biomimetic electrospray vapor chamber (BEVAC) which can potentially eliminate the wick structures and thermal interface materials used in conventional vapor chambers, and enable direct cooling of the backside of a microprocessor. This vapor chamber has a beetle-inspired superhydrophobic condenser with hydrophilic bumps on which condensate of the working fluid accumulates. The condensate is returned to the evaporator by electrostatic forces (electrospray

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... ization). We have demonstrated this novel liquid return mechanism with an open-system BEVAC prototype in which an external voltage is applied between a wickless evaporator and a microfabricated condenser with hybrid wettability.