Planar Bridging-Droplet Thermal Diode

This disclosure provides a thermal diode including a first plate having a first surface defining a wick structure. The thermal diode can include a second plate having a smooth surface facing the wick structure, the smooth surface and the wick structure defining a chamber for accommodating a phase-change liquid. The thermal diode also can include a separator positioned between the first plate and the second plate to separate the wick structure from the smooth surface by a gap that is less than a capillary length of the phase-change liquid.