Wang Fei, Chen Jianwen, Cui Xihua, Liu Xining, Chang Xiaohua, Zhu Yutian
College of Material, Chemistry and Chemical Engineering, Key Laboratory of Organosilicon Chemistry and Material Technology, Ministry of Education, Hangzhou Normal University, Hangzhou 311121, Zhejiang, People's Republic of China.
China-Australia Institute for Advanced Materials and Manufacturing, Jiaxing University, Jiaxing City, Zhejiang 314001, China.
ACS Appl Mater Interfaces. 2022 Jul 6;14(26):30268-30278. doi: 10.1021/acsami.2c09001. Epub 2022 Jun 25.
Fiber-shaped stretchable strain and temperature sensors are highly desirable for wearable electronics due to their excellent flexibility, comfort, air permeability, and easiness to be weaved into fabric. Herein, we prepare a smart ionogel-based fiber composed of thermoplastic polyurethane (TPU) and ionic liquid (IL) by the facile and scalable wet-spinning technique, which can serve as a wearable strain sensor with good linearity (a correlation coefficient of 0.997) in an ultrawide sensing range (up to 700%), ultralow-detection limit (0.05%), fast response (173 ms) and recovery (120 ms), and high reproducibility. Attributed to these outstanding strain sensing performances, the designed TPU/IL ionogel fiber-shaped sensor is able to monitor both subtle physiological activities and large human motions. More interestingly, because of the fast response and high resolution to strain, the fiber-shaped sensor can be sewn into the fabric to secretly encrypt and wirelessly translate message according to the principle of Morse code. More importantly, a wearable strain-insensitive temperature sensor can be obtained from the ionogel fiber if it is designed into an "S" shape, which can effectively eliminate the interference of strain on temperature sense. It is found that the inaccuracy of temperature sense is within 0.15 °C when the sensor is subjected to 30% tensile strain simultaneously. Moreover, this strain-insensitive temperature sensor shows a monotonic temperature response over a wide temperature range (-15 to 100 °C) with an ultrahigh detecting accuracy of 0.1 °C and good reliability, owing to the fast and stable thermal response of IL. This temperature sensor can realize the detection of thermal radiation, proximity, and respiration, exhibiting enormous potential in smart skin, personal healthcare, and wearable electronics. This work proposes a simple but effective strategy to realize the essential strain and temperature sensing capabilities of wearable electronics and smart fabrics without mutual interference.
纤维状可拉伸应变和温度传感器因其出色的柔韧性、舒适性、透气性以及易于编织成织物的特性，在可穿戴电子设备中备受青睐。在此，我们通过简便且可扩展的湿纺技术制备了一种由热塑性聚氨酯（TPU）和离子液体（IL）组成的基于智能离子凝胶的纤维，它可作为一种可穿戴应变传感器，在超宽传感范围（高达700%）内具有良好的线性度（相关系数为0.997）、超低检测限（0.05%）、快速响应（173毫秒）和恢复时间（120毫秒）以及高重现性。得益于这些出色的应变传感性能，所设计的TPU/IL离子凝胶纤维状传感器能够监测细微的生理活动和大幅度的人体运动。更有趣的是，由于对应变的快速响应和高分辨率，该纤维状传感器可缝入织物中，根据摩尔斯电码原理秘密加密并无线传输信息。更重要的是，如果将离子凝胶纤维设计成“S”形，可得到一种对应变不敏感的可穿戴温度传感器，它能有效消除应变对温度传感的干扰。研究发现，当传感器同时受到30%的拉伸应变时，温度传感的误差在0.15℃以内。此外，由于离子液体快速且稳定的热响应，这种对应变不敏感的温度传感器在很宽的温度范围（-15至100℃）内呈现单调的温度响应，具有0.1℃的超高检测精度和良好的可靠性。该温度传感器可实现对热辐射、接近度和呼吸的检测，在智能皮肤、个人医疗保健和可穿戴电子设备中展现出巨大潜力。这项工作提出了一种简单而有效的策略，可实现可穿戴电子设备和智能织物的基本应变和温度传感功能，且互不干扰。
