Department of Mechanical and Aerospace Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong.
Mater Horiz. 2021 May 1;8(5):1488-1498. doi: 10.1039/d1mh00018g. Epub 2021 Mar 8.
Continuous real-time measurement of body temperature using a wearable sensor is an essential part of human health monitoring. Electrospun aligned carbon nanofiber (ACNF) films are employed to assemble flexible temperature sensors. The temperature sensor prepared at a low carbonization temperature of 650 °C yields an outstanding sensitivity of 1.52% °C, high accuracy, good linearity, fast response time and excellent long-term durability. Moreover, it exhibits high discriminability towards temperature amidst other unwanted stimuli and maintains its original performance even after repeated stretch/release cycles because of highly-aligned structures. The correlation between the atomic structure and the temperature sensing performance of ACNF sensors is established. Contrary to conventional highly conductive temperature sensors, the ACNF sensor with a low electrical conductivity prepared at a low carbonization temperature ameliorates the temperature sensing performance. This anomaly is explained by (i) the smaller and more disordered sp carbon crystallites yielding a high negative temperature coefficient, (ii) a larger number of defects, and (iii) a higher pyridinic-N content generating abundant entrapped and localized electrons which are activated once sufficient thermal energy is available. Flexible ACNF sensor's overall performance is among the best-known carbon material-based flexible temperature sensors, demonstrating potential applications in emerging healthcare and flexible electronics technologies.
使用可穿戴传感器连续实时测量体温是人体健康监测的重要组成部分。静电纺丝定向碳纳米纤维 (ACNF) 薄膜被用于组装柔性温度传感器。在 650°C 的低温碳化温度下制备的温度传感器具有出色的灵敏度 1.52%°C、高精度、良好的线性度、快速响应时间和出色的长期耐用性。此外，它对温度具有很高的辨别能力，即使在经受重复拉伸/释放循环后，由于其高度定向的结构，仍能保持其原始性能。建立了 ACNF 传感器的原子结构与温度传感性能之间的相关性。与传统的高导电温度传感器相反，在低温碳化温度下制备的电导率较低的 ACNF 传感器改善了温度传感性能。这种异常现象可以通过以下三个方面来解释：(i) 较小且无序的 sp 碳微晶导致高负温度系数，(ii) 更多的缺陷，以及 (iii) 较高的吡啶-N 含量产生丰富的捕获和局域电子，一旦有足够的热能，这些电子就会被激活。柔性 ACNF 传感器的整体性能在基于已知碳材料的柔性温度传感器中是最好的之一，展示了在新兴医疗保健和柔性电子技术中的潜在应用。
