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

热舒适性是人类健康和生产力的最基本需求之一。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，室内温度控制也与巨大的能源消耗和碳排放相关联。这项拟议的工作旨在通过开发一种可穿戴辐射温度调节设备来打破健康能源的困境，该设备可以在人体周围进行局部热管理。就像变色龙可以改变其可见颜色一样，可穿戴设备可以像第二层皮肤一样改变辐射热损失到环境中的水平，以抵消不利的环境温度变化。热辐射通过使用小于1V作为操作电压的电化学反应来调谐。这种工作原理类似于电池，但重点在于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加热/冷却状态，比传统的有源设备如电热毯效率高出几个数量级。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与数学学院的Step Up to STEM计划合作，为代表性不足的学生组织名为LITE（光，红外和热能）的年度研讨会系列。该研讨会系列旨在通过提供介绍性讲座和沉浸式动手实验（如热视觉VR护目镜DIY课程），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，该器件采用金属-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，作为活性材料。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地且可逆地调谐，从而在超材料吸收体和简单的金属反射体之间改变装置状态，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，传热学和可穿戴设备工程的多尺度和多学科研究。具体而言，该项目将开发聚合物合成条件，结构表征，电荷传输测量，中红外介电常数，超材料吸收剂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、透气性和适形变形性。可穿戴元表面温度调节将进一步推进健康能源关系的多模式和多光谱光和热管理的新兴领域。电化学活性聚合物的深入研究也将成为自适应光学超颖表面、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NSF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.