School of Electrical Engineering and Computer Science (EECS) Gwangju Institute of Science and Technology (GIST) 123, Cheomdangwagi-ro, Bukgu Gwangju 61005 Republic of Korea.
Department of Biomedical Biological and Chemical Engineering University of Missouri Columbia MO 65211 USA.
Adv Sci (Weinh). 2021 Mar 9;8(10):2004885. doi: 10.1002/advs.202004885. eCollection 2021 May.
For wearable electronics/optoelectronics, thermal management should be provided for accurate signal acquisition as well as thermal comfort. However, outdoor solar energy gain has restricted the efficiency of some wearable devices like oximeters. Herein, wireless/battery-free and thermally regulated patch-type tissue oximeter (PTO) with radiative cooling structures are presented, which can measure tissue oxygenation under sunlight in reliable manner and will benefit athlete training. To maximize the radiative cooling performance, a nano/microvoids polymer (NMVP) is introduced by combining two perforated polymers to both reduce sunlight absorption and maximize thermal radiation. The optimized NMVP exhibits sub-ambient cooling of 6 °C in daytime under various conditions such as scattered/overcast clouds, high humidity, and clear weather. The NMVP-integrated PTO enables maintaining temperature within ≈1 °C on the skin under sunlight relative to indoor measurement, whereas the normally used, black encapsulated PTO shows over 40 °C owing to solar absorption. The heated PTO exhibits an inaccurate tissue oxygen saturation (StO) value of ≈67% compared with StO in a normal state (i.e., ≈80%). However, the thermally protected PTO presents reliable StO of ≈80%. This successful demonstration provides a feasible strategy of thermal management in wearable devices for outdoor applications.
对于可穿戴电子/光电设备，需要进行热管理，以确保准确的信号采集和热舒适性。然而，户外太阳能的获取限制了一些可穿戴设备（如血氧计）的效率。本文提出了一种无线/无电池、具有热调节功能的贴片式组织血氧计（PTO），带有辐射冷却结构，可以在阳光照射下可靠地测量组织的氧合情况，这将有利于运动员的训练。为了最大限度地提高辐射冷却性能，通过结合两种穿孔聚合物，引入了纳米/微空隙聚合物（NMVP），以降低阳光吸收并最大化热辐射。在各种条件下，如散射/阴天、高湿度和晴天，优化后的 NMVP 可实现 6°C 的亚环境冷却。与室内测量相比，NMVP 集成的 PTO 可使皮肤表面的温度在阳光照射下保持在 ≈1°C 左右，而通常使用的黑色封装的 PTO 由于太阳能吸收而显示出超过 40°C 的温度。加热后的 PTO 显示出不准确的组织氧饱和度（StO）值，约为 67%，而正常状态下的 StO 值约为 80%（即 ≈80%）。然而，受保护的 PTO 可以提供可靠的 StO 值，约为 80%。这项成功的演示为户外应用的可穿戴设备中的热管理提供了一种可行的策略。
