A Triple-Mode Midinfrared Modulator for Radiative Heat Management of Objects with Various Emissivity

Abstract

Thermal management is ubiquitous in the modern world and indispensable for a sustainable future. Radiative heat management provides unique advantages because the heat transfer can be controlled by the surface. However, different object emissivities require different tuning strategies, which poses challenges to develop dynamic and universal radiative heat management devices. Here, we demonstrate a triple-mode midinfrared modulator that can switch between passive heating and cooling suitable for all types of object surface emissivities. The device comprises a surface-textured infrared-semiabsorbing elastomer coated with a metallic back reflector, which is biaxially strained to sequentially achieve three fundamental modes: emission, reflection, and transmission. By analyzing and optimizing the coupling between optical and mechanical properties, we achieve a performance as follows: emittance contrast Δε = 0.58, transmittance contrast Δτ = 0.49, and reflectance contrast Δρ = 0.39. The device can provide a new design paradigm of radiation heat regulation for wearable, robotics, and camouflage technologies.

Dual-Emitter Graphene Glass Fiber Fabric for Radiant Heating

“…Notably, glass fiber is a good infrared radiation material originating from the Si−O bond vibration with high emissivity around 0.8. 1,19 Based on the theoretical emissivity of 0.023 for monolayer graphene, GGFF-300 with ∼15 layers of graphene would present an emissivity of 0.29 (see details in Supplementary Note). 22 Actually, the emissivity of GGFF-300 is 0.84, much higher than the theoretical value of 0.29 (Figure 2c).…”

“…The emissivity of GGFF is much higher than that of graphene fiber (∼0.7) and metals (<0.3), which is mainly attributed to the layer-dependent radiation capability of graphene and the intrinsic infrared radiation characteristics of the glass fiber. Notably, glass fiber is a good infrared radiation material originating from the Si–O bond vibration with high emissivity around 0.8. , Based on the theoretical emissivity of 0.023 for monolayer graphene, GGFF-300 with ∼15 layers of graphene would present an emissivity of 0.29 (see details in Supplementary Note). Actually, the emissivity of GGFF-300 is 0.84, much higher than the theoretical value of 0.29 (Figure c).…”

“…component being silica, is a good infrared radiation material originating from the Si−O bond vibration, showing high infrared emissivity around 0.8. 1,19 Considering the properties of graphene and glass fibers, the design of combining these two materials to develop an advanced dual-emitter infrared electrothermal material, graphene glass fiber (GGF), was proposed, where graphene works as the heating element and both components work as the radiating elements. Herein, chemical vapor deposition (CVD) was used to realize the preparation of GGF, including GGF bundles (GGFB) and fabric (GGFF), by directly growing graphene on glass fibers.…”

“…Thermal radiation, as a typical contactless heat transfer mode, shows significant advantages, such as high thermal effect, media-free operation, good penetration, and compatibility for different heated shapes. The infrared radiation thermal management technique has been widely developed for applications in radiative heating and cooling, thermal energy harvesting, infrared detection, and communications. , In addition, the radiant heating has also been widely applied in food manufacturing, coating solidification, therapy, and sterilization . According to the Stefan–Boltzmann law, one of the effective ways to modulate radiation is controlling the temperature with Joule heating by applying voltage to conductive infrared electrothermal materials.…”

“…Glass fiber is a commercial lightweight (density ∼2.1 g cm –3 ) structural material with high mechanical strength and flexibility, as well as large specific surface area, and has been widely used as a reinforcing material for applications in aircraft, automobiles, etc . − Notably, glass fiber, with the main component being silica, is a good infrared radiation material originating from the Si–O bond vibration, showing high infrared emissivity around 0.8. , Considering the properties of graphene and glass fibers, the design of combining these two materials to develop an advanced dual-emitter infrared electrothermal material, graphene glass fiber (GGF), was proposed, where graphene works as the heating element and both components work as the radiating elements.…”