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

热舒适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，由于其必要性，室内温度控制也伴随着巨大的能源消耗和碳排放。这项工作旨在通过开发一种可穿戴的辐射热调节装置来打破健康-能量困境，该装置可以在人体周围进行局部热管理。就像变色龙可以改变自己的可见颜色一样，这种可穿戴设备可以像第二层皮肤一样，改变辐射热量散失到环境中的水平，以抵消不利的环境温度变化。热辐射通过电化学反应来调节，该电化学反应使用低于1 V的工作电压。这种工作原理类似于电池，但重点是其中红外光学特性的变化。就像电池可以长时间保持充电状态一样，该设备也可以以超低的能耗保持其加热/冷却状态，比电热毯等传统有源设备的效率提高了几个数量级。为了促进多样性、公平性和包容性，该项目将与北卡罗来纳州科学与数学学院的“迈向STEM”项目合作，为代表性不足的学生组织名为LITE（光、红外和热能）的年度系列研讨会。该系列研讨会旨在通过提供入门讲座和沉浸式动手实验（如热视觉VR护目镜DIY课程）来激发高中生对光子学，热科学和一般STEM领域的兴趣。在光子技术术语中，该装置采用金属-绝缘体-金属结构和中红外超材料完美吸收器的工作原理。它采用聚苯胺等电致变色共轭聚合物作为活性物质。通过电化学偏置聚合物，其载流子密度、等离子体频率和介电常数被动态可逆地调谐，从而改变器件在超材料吸收器和简单金属反射器之间的状态，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谐。该项目将涉及材料科学、光子学、传热和可穿戴设备工程等多学科的多尺度研究。具体而言，该项目将发展聚合物合成条件、结构表征、电荷输运测量、中红外介电常数、超材料吸收器设计和传热测量之间的相关性。拟议的研究将扩大自适应超材料吸收器的规模，并实施Kirigami剪纸技术，为可穿戴应用提供从2D薄膜到3D形状的拉伸性、透气性和保形变形性。可穿戴的超表面温度调节将进一步推动多模态和多光谱的光和热管理领域的发展，以实现健康和能量的联系。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者。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值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.