Zhang Qiankun, An Chunhua, Fan Shuangqing, Shi Sigang, Zhang Rongjie, Zhang Jing, Li Quanning, Zhang Daihua, Hu Xiaodong, Liu Jing
State Key Laboratory of Precision Measurement Technology and Instruments, School of Precision Instruments and Opto-electronics Engineering, Tianjin University, 92 Weijin Rd., Tianjin, 300072, People's Republic of China.
Nanotechnology. 2018 Jul 13;29(28):285501. doi: 10.1088/1361-6528/aabf2f. Epub 2018 Apr 18.
Minimizing the strain-induced undesirable effects is one of the major efforts to be made for flexible electronics. This work demonstrates a highly sensitive flexible gas sensor with ultra-low strain response, which is potentially suitable for wearable electronics applications. The gas sensing material is a free-standing and flexible thin film made of graphene/ethyl cellulose (EC) nanocomposite, which is then integrated with flexible substrate of polyethylene terephthalate. The sensor exhibits relative resistance change within 0.3% at a minimum bending radius of 3.18 mm and 0.2% at the bending radius of 5 mm after 400 bending cycles. The limited strain response attributes to several applied strategies, including using EC with high Young's modulus as the matrix material, maintaining high graphene concentration and adopting suspended device structure. In contrast to the almost negligible strain sensitivity, the sensor presents large and rapid responses toward volatile organic compounds (VOCs) at room temperature. Specifically, the sensor resistance rapidly increases upon the exposure to VOCs with detection limits ranging from 37 to 167 ppm. A preliminary demo of wearable gas sensing capability is also implemented by wearing the sensor on human hand, which successfully detects several VOCs, instead of normal hand gestures.
将应变诱导的不良影响降至最低是柔性电子学领域需要做出的主要努力之一。这项工作展示了一种具有超低应变响应的高灵敏度柔性气体传感器，它可能适用于可穿戴电子设备应用。气体传感材料是一种由石墨烯/乙基纤维素（EC）纳米复合材料制成的独立柔性薄膜，然后与聚对苯二甲酸乙二醇酯柔性基板集成。该传感器在最小弯曲半径为3.18毫米时，经过400次弯曲循环后，相对电阻变化在0.3%以内；在弯曲半径为5毫米时，相对电阻变化在0.2%以内。有限的应变响应归因于几种应用策略，包括使用高杨氏模量的EC作为基体材料、保持高石墨烯浓度以及采用悬浮器件结构。与几乎可以忽略不计的应变灵敏度形成对比的是，该传感器在室温下对挥发性有机化合物（VOCs）呈现出大且快速的响应。具体而言，当暴露于检测限范围为37至167 ppm的VOCs时，传感器电阻会迅速增加。通过将传感器佩戴在人手上，还实现了可穿戴气体传感能力的初步演示，它成功检测到了几种VOCs，而不是正常的手势。
