CAREER: Electrochemical Dynamic Midinfrared Metasurface for Ultra-Low Power Wearable Thermoregulation

热舒适性是人类健康和生产力最基本的需求之一。心血管疾病和流感的季节性表明了稳定我们的热环境的重要性。然而，由于室内温度控制的必要性，室内温度控制也伴随着巨大的能源消耗和碳排放。这项拟议的工作旨在通过开发一种可穿戴的辐射体温调节设备来打破健康和能量的困境，该设备可以对人体周围的热量进行局部管理。就像变色龙可以改变自己的可见颜色一样，这款可穿戴设备可以像第二层皮肤一样，改变环境中辐射热损失的水平，以抵消不利的环境温度变化。通过电化学反应来调节热辐射，该电化学反应使用小于1V的工作电压。这种工作原理类似于电池，但重点在于其中红外光学性质的变化。就像电池可以长时间保持其充电状态一样，该设备还可以以超低的能耗保持其加热/冷却状态，其效率比电热毯等传统有源设备高出数量级。为了促进多样性、公平性和包容性，该项目将通过与北卡罗来纳州科学和数学学院的Step Up to STEM计划合作，为代表不足的学生组织名为LITE(光、红外和热能)的年度研讨会系列。该系列工作坊旨在通过提供入门课程和身临其境的动手实验(如热视VR护目镜DIY课程)来激发高中生对光子学、热学和普通STEM领域的兴趣。在光子技术术语中，该器件采用了金属-绝缘体-金属结构和中红外超材料完美吸收体的工作原理。它使用电致变色共轭聚合物，如聚苯胺，作为活性物质。通过电化学偏置聚合物，其载流子密度、等离子体激元频率和介电常数可以动态和可逆地调谐，从而改变了超材料吸收体和简单金属反射体之间的器件状态，这相当于基于基尔霍夫热辐射定律和零透射率的发射率调节。该项目将涉及材料科学、光子学、传热学和可穿戴设备工程的多尺度和多学科研究。具体地说，该项目将发展聚合物合成条件、结构表征、电荷传输测量、中红外介电常数、超材料吸波材料设计和热传递测量之间的相关性。这项拟议的研究将扩大自适应超材料吸波材料的规模，并实施Kirigami剪纸技术，为可穿戴应用提供从2D薄膜到3D形状的延伸性、透气性和保形变形性。可穿戴式亚表面温度调节将进一步推动健康-能源关系的多模式和多光谱光和热管理的新兴领域。对电化学活性聚合物的深入研究也将成为自适应光学超表面、可持续能源科学和个性化预防医学的推动因素。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Thermal comfort is one of the most essential fundamental needs for human health and productivity. The seasonality of cardiovascular diseases and influenza demonstrates the importance of stabilizing our thermal environments. However, because of its necessity, indoor temperature control is also associated with enormous energy consumption and carbon emission. This proposed work aims to break the health-energy dilemma by developing a wearable radiative thermoregulation device that can localize heat management around the human body. Like a chameleon that can change its visible color, the wearable device can act like a second skin that changes the level of radiative heat loss into the environment to offset the adverse ambient temperature change. The thermal radiation is tuned by an electrochemical reaction that uses less than 1 V as operation voltage. This working principle is similar to a battery but with the focus on its mid-infrared optical property change. Like a battery that can maintain its state of charge for a long time, the device can also maintain its heating/cooling state with ultralow energy consumption, which is orders of magnitude more efficient than traditional active devices such as electric blankets. To promote diversity, equity, and inclusion, the project will organize the annual workshop series called LITE (Light, Infrared, and Thermal Energy) for underrepresented students by collaborating with the Step Up to STEM program at North Carolina School of Science and Mathematics. The workshop series aims to inspire high schoolers’ interest in photonics, thermal science, and general STEM fields by providing introductory lectures and immersive hands-on experiments such as thermal vision VR goggle DIY sessions. In photonic technical terms, the device adopts a metal-insulator-metal configuration and the working principle of a midinfrared metamaterial perfect absorber. It uses electrochromic conjugated polymer, such as polyaniline, as the active material. By electrochemically biasing the polymer, its carrier density, plasmon frequency, and permittivity are tuned dynamically and reversibly, thus varying the device state between a metamaterial absorber and a simple metallic reflector, which is equivalent to emissivity tuning based on the Kirchhoff’s law of thermal radiation and the zero transmittance. This project will involve multiscale and multidisciplinary study in materials science, photonics, heat transfer, and wearable device engineering. Specifically, the project will develop the correlation among polymer synthesis condition, structural characterization, charge transport measurement, mid-infrared permittivity, metamaterial absorber designs, and heat transfer measurement. The proposed research will scale up the adaptive metamaterial absorber and implement Kirigami paper cutting technique to provide stretchability, breathability, and conformal deformability from 2D thin film to 3D shapes for wearable applications. The wearable metasurface thermoregulation will further advance the emerging field of multimodal and multispectral light and heat management for the health-energy nexus. The in-depth study of electrochemically active polymers will also become an enabler for adaptive optical metasurfaces, sustainable energy science, and personalized preventive medicine.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.