The ability to manipulate heat flow can result in wonderful applications such as thermal logic and memory devices. Thermal logic and memory devices are similar to their electronic counterparts, however, they are powered solely by heat. In addition, thermal logic and memory devices can operate in harsh environments where electronics typically fail. Despite our understanding of various mechanisms of heat transfer, controlling heat (in a sense of switching heat flow on or off) is more challenging than controlling electricity due to the lack of perfect thermal insulators. One possible solution is to control the near-field thermal radiation heat transfer between hot and cold terminals by manipulating the size of the vacuum gap separating the two. Unlike far-field thermal radiation, near-field thermal radiation intensity increases exponentially with decreasing the gap size. There are however challenges in manipulating the nano/micro vacuum gaps to achieve enough contrast in heat transfer between the high and low heat transfer cases. In this paper, we present a prototype of a microdevice with a controllable micro gap of size 3 μm (initial gap size) between the hot and cold terminals; this configuration achieves a contrast in near-field radiative heat transfer at temperatures as high as 600 K. Furthermore, we present numerical analysis for meshed photonic crystals to achieve even higher contrast in radiative heat transfer with enhancement in heat transfer as high as 26 times in comparison to far-field.
Nanoscale Thermal Transfer – An Invitation to Fluctuation Electrodynamics
