Thermal homeostasis using microstructured phase-change materials

Humans and other warm-blooded mammals maintain their body temperature within a narrow range in a process called homeostasis. This ability to maintain an internal temperature, which is relatively insensitive to changes in the external environment or heat load is vital for all complex processes that sustain life. Without the ability to regulate temperature, materials and devices that experience large temperature gradients or temperature cycles are vulnerable to performance degradation or even catastrophic failure. Thermal control akin to the way living organisms achieve thermal homeostasis is particularly important in environments such as space, where changing solar illumination can cause large temperature variations. Various systems have been used to mitigate temperature fluctuations; however, they tend to be bulky and require power. Here, we model micropatterned phase-change materials to design an efficient, solid-state alternative, which requires no external input power. Our design is based on switchable thermal emission, which takes advantage of temperature-induced phase-change behavior in thin films of vanadium oxide on silicon microcones.