Collaborative Research: Dynamic Thermal Radiation Control using Crumpled 2D-Xene Materials for Wearable Devices

非技术：可穿戴设备对热管理提出了独特的挑战。冷却或加热系统必须灵活，能够适应不断变化的条件。例如，阳光直射会产生强烈的加热效果。然而，用于热辐射控制的传统冷却或加热系统是基于刚性结构的，不能适应不断变化的条件。可穿戴设备的热辐射控制需要一种新的机制来选择性地、动态地调节光吸收和红外发射。自然界中有很多例子可以通过表面结构来改变颜色或调节体温。受沙漠蚂蚁和变色龙等自然界独特例子的启发，pi将创建一个选择性发射器，并将其与可拉伸的聚合物基板集成，以实现动态热辐射控制。这个概念是基于二维（2D）材料（如石墨烯和磷烯）形态的可控变化。这些材料被称为2D-Xenes，是一种以可逆方式控制热辐射的新平台。这项研究将有助于更好地理解二维材料的形态、光谱发射率和温度之间的关系。反过来，这项工作将在可穿戴设备的热管理方面取得突破。pi将整合研究和教学，并建立一个扩展计划，以激发K-12学生，代表性不足的学生和退伍军人的科学兴趣。pi还将在参与机构之间组织合作外展活动。联合研讨会将使学生在pi各自的实验室中接触到最先进的研究和教育机会。技术方面：在过去的几十年里，我们在控制电和光方面的知识的进步在电子学和光子学领域取得了革命性的进展，但我们在控制热方面的知识却取得了相对较少的进展。pi的目标是通过提出新的热辐射控制材料设计和确定可穿戴设备动态热辐射控制的新机制，为科学界做出重大贡献。该项目的主要目标是利用2D-Xene材料（如石墨烯和磷烯）建立对微尺度到纳米尺度形态、光谱发射率和温度之间关系的基本理解，并为可穿戴设备实现动态热辐射控制。pi将结合纳米力学和热科学方面的互补专业知识，通过机械应变诱导的皱缩来展示2D-Xene材料的独特形态控制，并通过计算和实验方法研究不同皱缩水平对热性能的影响。提出的研究的主要假设是，应变诱导的皱褶2D-Xene材料的形态变化导致可穿戴设备发射光谱的选择性变化和温度的显着变化。在提出的材料设计中，可控的应变诱导的形态变化允许定量实验研究，这将揭示形态依赖的发射率特征，以及发射率依赖的温度。该项目将通过严格的耦合波分析和时域有限差分计算来阐明皱巴巴的2D-Xene材料中的太阳吸收和红外发射现象。该项目将确定热辐射控制的极限，并为可穿戴设备提供可行的热管理途径。例如，手腕运动引起的应变可以改变2D-Xene材料的形态，基于2D-Xene材料的选择性发射器将提供动态热辐射控制。通过这项工作，该项目将解释由皱巴巴的2D-Xene材料产生的人工周期性如何导致发射率和温度调制，并为可穿戴设备实现预测建模。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。

Nontechnical:Wearable devices pose unique challenges for thermal management. The cooling or heating system must be flexible and able to adapt to changing conditions. For example, direct sunlight can have a strong heating effect. Conventional cooling or heating systems for thermal radiation control, however, are based on rigid structures and cannot adapt to changing conditions. Thermal radiation control for wearable devices requires a novel mechanism to selectively and dynamically modulate light absorption and infrared emission. There are many examples in nature that can change color or regulate body temperature using surface structures. Inspired by unique examples in nature such as desert ants and chameleons, the PIs will create a selective emitter and integrate it with a stretchable polymer substrate to enable dynamic thermal radiation control. The concept is based on a controllable variation in the morphology of two-dimensional (2D) materials such as graphene and phosphorene. These materials, called 2D-Xenes, are a novel platform to control thermal radiation in a reversible manner. The research will lead to a better understanding of relationships morphology, spectral emissivity, and temperature in 2D materials. In turn, the work will breakthroughs in thermal management of wearable devices. The PIs will integrate research and teaching and establish an outreach program that will spark the scientific interest of K-12 students, underrepresented students, and veterans. The PIs will also organize collaborative outreach events across the participating institutions. Joint workshops will expose students to state-of-the-art research and education opportunities in the PIs' respective laboratories.Technical:Over the past several decades, advances in our knowledge of controlling electricity and light has made revolutionary progress in the field of electronics and photonics, but our knowledge of controlling heat has made relatively little progress. The PIs aim to add significant contributions to the scientific community by presenting novel material designs of thermal radiation control and identifying novel mechanisms of dynamic thermal radiation control for wearable devices. The main objectives of this project are to establish a fundamental understanding of relationships between microscale-to-nanoscale morphology, spectral emissivity, and temperature using 2D-Xene materials such as graphene and phosphorene and to enable dynamic thermal radiation control for wearable devices. The PIs will combine complementary expertise in nanomechanics and thermal sciences to demonstrate unique morphology control in 2D-Xene materials via mechanical-straining-induced crumpling and investigate the effects of varying crumpling levels in thermal properties through computational and experimental approaches. The major hypothesis of the proposed research is that strain-induced morphology variations in crumpled 2D-Xene materials lead to selective changes in the emissivity spectrum and to significant changes in temperature for wearable devices. The controllable strain-induced morphology variation in the proposed material design allows quantitative experimental investigations, which will reveal characteristics of morphology-dependent emissivity, and emissivity-dependent temperature. The project will elucidate solar absorption and infrared emission phenomena in crumpled 2D-Xene materials via rigorous coupled-wave analysis and finite-difference time-domain computations. The project will identify the limits of thermal radiation control and present viable pathways of thermal management for wearable devices. For instance, strains induced by a wrist movement can change the morphology of the 2D-Xene material and the 2D-Xene material-based selective emitter will provide dynamic thermal radiation control. Through this work, the project will explain how artificial periodicities created by crumpled 2D-Xene materials lead to emissivity and temperature modulations and enable predictive modeling for wearable devices.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.