GOALI: Microscale fundamentals of sweat evaporation

GOALI：汗液蒸发的微观基础

• 批准号: 2214152
• 负责人: Konrad Rykaczewski
• 金额: $ 45.37万
• 依托单位: Arizona State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-08-01 至 2025-07-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2214152&HistoricalAwards=false
• 关键词: GOALI; Microscale; fundamentals; sweat; evaporation

Sweating is important to human thermoregulation, thermal comfort, illness diagnosis, and hygiene product development. However, little is known about how droplets emerge and evaporate from our sweat glands. The scale of these phenomena is in-between molecular processes that drive sweat generation revealed by biochemists and macroscopic sweat rate measurements performed by physiologists. Engineers have studied evaporation across all these length scales but only in non-biological settings. This work will use three advanced imaging techniques to provide a unique view of droplets during various sweating stages. To identify the main physical mechanisms underlying sweat evaporation, high-resolution photographs and videos will be interpreted with theoretical modeling and additional experimentation with artificial sweating surfaces. These research outcomes will potentially impact diverse fields ranging from medical diagnostic development to energy-efficient building design. In addition, the work will inform the industrial partner how to more realistically mimic sweating using a thermal manikin. These devices are often used in apparel development and to optimize airflow for human thermal comfort in buildings and vehicles. The project will foster the academia-industry partnership with various joint activities and engage with the broader public through multimedia platforms and campus events. To systematically understand the role of various thermofluidic factors in different sweat evaporation modes, the project team proposes a two-pronged transdisciplinary approach that merges physiological and engineering perspectives. First, a new method will be developed to integrate ventilated capsule sweat rate measurements used routinely in physiology with multimodal imaging. Specifically, the team will use fast macro videography, mid-wave infrared thermography, and optical coherence tomography. A suite of non-invasive methods will be used to simultaneously measure sweat evaporation rate and visualize the corresponding microscale sweat dynamics at three skin sites. The team will study these processes under neutral, moderate, and strong thermal stimuli that will be asserted to induce out-of-pore, dropwise, and filmwise sweating modes. Second, the contributions of various factors to sweat evaporation through experimentation and modeling will be explored employing the same method but with artificial sweating surfaces with gradually increasing complexity. This knowledge will enable the formulation of reduced-order models of the out-of-pore, dropwise, and filmwise modes. In addition, imaging sweating onset and drying phases will deepen understanding of biological processes, including how sweat traverses through the duct to the skin and what happens to sweat on the surface once its secretion stops.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.

出汗对于人体体温调节、热舒适、疾病诊断和卫生产品开发很重要。然而，人们对液滴如何从我们的汗腺中产生和蒸发知之甚少。这些现象的规模介于生物化学家揭示的驱动出汗的分子过程和生理学家进行的宏观出汗率测量之间。工程师们研究了所有这些长度尺度的蒸发，但仅限于非生物环境。这项工作将使用三种先进的成像技术来提供各个出汗阶段液滴的独特视图。为了确定汗液蒸发的主要物理机制，将通过理论模型和人工出汗表面的额外实验来解释高分辨率照片和视频。这些研究成果将可能影响从医疗诊断开发到节能建筑设计等各个领域。此外，这项工作还将告知工业合作伙伴如何使用热人体模型更真实地模拟出汗。这些设备通常用于服装开发，并优化气流以提高建筑物和车辆中的人体热舒适度。该项目将通过各种联合活动促进学术界与工业界的伙伴关系，并通过多媒体平台和校园活动与更广泛的公众互动。为了系统地了解各种热流体因素在不同汗液蒸发模式中的作用，项目团队提出了一种融合生理学和工程学视角的双管齐下的跨学科方法。首先，将开发一种新方法，将生理学中常规使用的通气胶囊出汗率测量与多模态成像相结合。具体来说，该团队将使用快速宏观摄像、中波红外热成像和光学相干断层扫描。将使用一套非侵入性方法同时测量汗液蒸发率并可视化三个皮肤部位相应的微尺度汗液动态。该团队将在中性、中等和强烈的热刺激下研究这些过程，据称这些热刺激会诱导出毛孔、滴状和薄膜状出汗模式。其次，将通过实验和建模探索各种因素对汗液蒸发的贡献，采用相同的方法，但使用逐渐增加复杂性的人工出汗表面。这些知识将使得能够制定出孔外、滴状和膜状模式的降阶模型。此外，对出汗开始和干燥阶段进行成像将加深对生物过程的理解，包括汗液如何通过导管到达皮肤，以及汗液停止分泌后表面会发生什么情况。该奖项反映了 NSF 的法定使命，并被认为是值得的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来获得支持。