Institute of Materials , China Academy of Engineering Physics , Jiangyou 621908 , Sichuan , P. R. China.
ACS Appl Mater Interfaces. 2018 Jul 18;10(28):23987-23996. doi: 10.1021/acsami.8b07373. Epub 2018 Jul 2.
This paper reports a fast and highly sensitive all-graphene humidity sensor working in a novel alternating current (ac) detection mode for the first time, which is capable of sensing humidity on a smartphone for portable electronics. The humidity sensor is based on an interdigitated reduced graphene oxide/graphene oxide/rGO (rGO/GO/rGO) structure patterned by a facile laser direct writing method. It works in an ac sensing mode with a rectangular input voltage wave and measures the output voltage wave instead of conventional resistance, impedance, or capacitance, exhibiting a dramatically enhanced sensitivity by about 45 times compared to the low and unstable response in dc mode. The humidity sensor shows an obvious response to the relative humidity (RH) ranging from RH 6.3% to RH 100%. The response and recovery toward humidity change are almost instantaneous, and the corresponding costed times including humidity rise and decay times are less than 1.9 and 3.9 s, respectively, which are among the best results in the literature. The sensor also exhibits outstanding cycling stability, flexibility, and long-term stability (>1 year), as well as good reproducibility of device preparation. Besides, it can be easily connected to an iPhone and the humidity sensing can be conducted with an oscilloscope application on iOS. What's more, an electronic circuit simulation method was employed to fit the output waves, which can not only explain the sensing mechanism, but also determine the resistance and capacitance of the rGO/GO/rGO structure, agreeing well with the results obtained from the electrochemical measurements. It can be reasonably expected that the approach combining humidity sensing and electronic circuit simulation can be applied in real-time monitoring on a smartphone based on the Internet of things and big data technologies.
本文首次报道了一种基于新型交流电（ac）检测模式的快速、高灵敏度全石墨烯湿度传感器，该传感器可用于智能手机上的便携式电子产品进行湿度感应。该湿度传感器基于通过简便的激光直写方法图案化的叉指型还原氧化石墨烯/氧化石墨烯/rGO(rGO/GO/rGO)结构。它在 ac 感应模式下工作，采用矩形输入电压波并测量输出电压波，而不是传统的电阻、阻抗或电容，与直流模式下的低且不稳定的响应相比，灵敏度提高了约 45 倍。该湿度传感器对相对湿度 (RH) 从 6.3%到 100%表现出明显的响应。对湿度变化的响应和恢复几乎是瞬时的，相应的耗时包括湿度上升和衰减时间分别小于 1.9 和 3.9 秒，这是文献中最好的结果之一。该传感器还表现出出色的循环稳定性、灵活性和长期稳定性（>1 年），以及器件制备的良好重现性。此外，它可以很容易地与 iPhone 连接，并且可以使用 iOS 上的示波器应用程序进行湿度感应。更重要的是，采用电子电路模拟方法来拟合输出波，不仅可以解释传感机制，还可以确定 rGO/GO/rGO 结构的电阻和电容，与电化学测量的结果吻合良好。可以合理地预期，将湿度感应与电子电路模拟相结合的方法可以应用于基于物联网和大数据技术的智能手机的实时监测。
