Wang Chengkai, Jiao Chunxiao, Wang Meng, Pan Jinghong, Wang Qi
College of Sciences, Northeastern University, Shenyang 110819, China.
Nanomaterials (Basel). 2023 Jun 24;13(13):1925. doi: 10.3390/nano13131925.
In recent years, LC resonant sensors have gained widespread attention for their extensive applications in industries such as pharmaceutical storage and food transportation. A wireless passive sensor with a good sensing performance is proposed based on a GO/CNT-OH/Nafion nanocomposite. The sensor was fabricated via inkjet printing technology, and the surface morphology of the GO/CNT-OH/Nafion nanocomposite was characterized by SEM measurement. It is found that the MWCNTs support the GO layer and the hydrophobic chains of Nafion interact with the hydrophobic layer of GO, resulting in a larger cavity and hydrophilic surface of the entire material. This structure well reflects the fact that the mixing of MWCNTs and Nafion provides the entire material with a stronger water absorption. The experimental study shows that the proposed humidity sensor has a frequency variation of 103 kHz/%RH at low humidity (30-60% RH) and a sensitivity of 931 kHz/%RH at high humidity (60-95% RH), while the sensitivity value from 30-95% RH is 547 kHz/% RH. The response time and recovery time are 110 s and 115 s, respectively. In addition, the tests showed that the GO/CNT-OH/Nafion nanocomposite applied to the humidity sensor had a maximum humidity hysteresis of about 3% RH at 30-95% RH, the resonant frequency remained basically unchanged after 50 h of testing, and the whole sensor possessed a good stability. After conducting several repeated experiments, it was found that the resonant frequency error of the whole sensor was low and did not affect the overall sensing test, which proved the reproducible preparation of the sensor. Finally, the humidity-sensing mechanism of the proposed sensor was analyzed in this paper, and it was found that GO enhanced the hygroscopic properties of GO/CNT-OH/Nafion nanocomposite when it was supported by MWCNT-OH and included uniformly dispersed Nafion. Therefore, our proposed humidity sensor is suitable for humidity detection above 30% RH in both sealed and open environments.
近年来，LC谐振传感器因其在药品储存和食品运输等行业的广泛应用而受到广泛关注。基于氧化石墨烯/碳纳米管-羟基/全氟磺酸（GO/CNT-OH/Nafion）纳米复合材料，提出了一种具有良好传感性能的无线无源传感器。该传感器通过喷墨打印技术制备，并通过扫描电子显微镜（SEM）测量对GO/CNT-OH/Nafion纳米复合材料的表面形貌进行了表征。研究发现，多壁碳纳米管（MWCNTs）支撑着氧化石墨烯层，全氟磺酸的疏水链与氧化石墨烯的疏水层相互作用，使得整个材料具有更大的空腔和亲水表面。这种结构很好地反映了MWCNTs和全氟磺酸的混合为整个材料提供了更强吸水性这一事实。实验研究表明，所提出的湿度传感器在低湿度（30-60%RH）下频率变化为103kHz/%RH，在高湿度（60-95%RH）下灵敏度为931kHz/%RH，而在30-95%RH范围内灵敏度值为547kHz/%RH。响应时间和恢复时间分别为110秒和115秒。此外，测试表明，应用于湿度传感器的GO/CNT-OH/Nafion纳米复合材料在30-95%RH下最大湿度滞后约为3%RH，测试50小时后谐振频率基本保持不变，整个传感器具有良好的稳定性。经过多次重复实验发现，整个传感器的谐振频率误差较低，不影响整体传感测试，这证明了传感器的可重复制备。最后，本文分析了所提出传感器的湿度传感机制，发现当氧化石墨烯由MWCNT-OH支撑并包含均匀分散的全氟磺酸时，增强了GO/CNT-OH/Nafion纳米复合材料的吸湿性能。因此，我们提出的湿度传感器适用于密封和开放环境中30%RH以上的湿度检测。
