Liu, T., Palko, J.W., Katz, J.S., Dede, E.M., Zhou, F., Asheghi, M., and Goodson, K.E., 2019, “Tunable, Passive Thermal Regulation through Liquid to Vapor Phase Change,” Applied Physics Letters, Vol. 115, 254102. DOI: 10.1063/1.5133795.
The increasing complexity and power density of electronic systems have necessitated the development of thermal circuits that can not only remove but actively redirect the flow of heat. Passive thermal regulators are promising as heat routing components that can mitigate large temperature spikes by transitioning between high and low resistance states without external actuation. Existing regulators, however, are often either limited to fixed temperature regulation ranges due to solid-state material property limitations or are difficult to package in a compact form factor. Here, we present a passive, compact (1 × 1 cm2 active area), and tunable thermal regulator that functions based on the dynamics of vapor transport through a noncondensable gas cavity. The device demonstrates a switching resistance ratio of 4 in response to variations in the input power ranging from approximately 0.6 W to 14 W. The device is also able to set the temperature difference across the hot and cold sides to a fixed, “clamped” value that is reasonably independent of heat flow. Both the overall resistance and the clamped temperature difference can be easily tuned by presetting the pressure of the noncondensable gas. We present a brief analysis of the physical operating principles of the device and lay the groundwork for the development of future passive and tunable thermal circuitry components.