Department of Robotics and Mechatronics Engineering, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu, 42988, Korea.
Robotics and Mechatronics Research Center, DGIST, Daegu, 42988, Korea.
Sci Rep. 2023 Apr 26;13(1):6838. doi: 10.1038/s41598-023-34099-7.
This work presents the single-chip integration of a multi-frequency surface acoustic wave resonator (SAWR) based humidity sensor. Graphene oxide (GO), a humidity-sensing material, is integrated onto a confined sensing area of SAWR via electrospray deposition (ESD). The ESD method allows ng-resolution deposition of GO, optimizing the amount of sensing material. The proposed sensor consists of SWARs at three different resonant frequencies (180, 200 and 250 MHz) with a shared common sensing region, thus allowing direct analysis of sensor performances at different operating frequencies. Our findings reveal that the resonant frequency of the sensor impacts both measurement sensitivity and stability. A higher operating frequency ensures better sensitivity but suffers from a larger damping effect from absorbed water molecules. The maximum measurement sensitivity of 17.4 ppm/RH% is achieved with low drift. In addition, the developed sensor exhibits improved stability and sensitivity by as much as 150% and 75% in frequency shift and Quality factor (Q), respectively, by carefully selecting the operating frequencies at a given RH% range. Finally, the sensors are used for various hygienic applications, such as non-contact proximity detection and face mask inspection.
本工作提出了一种基于多频声表面波谐振器(SAWR)的单片集成湿度传感器。通过电喷雾沉积(ESD)将氧化石墨烯(GO)这一湿度敏感材料集成到 SAWR 的受限感测区域上。ESD 方法允许进行纳克级分辨率的 GO 沉积,从而优化感测材料的用量。所提出的传感器由三个不同谐振频率(180、200 和 250 MHz)的 SAWR 组成,具有共用的公共感测区域,从而可以在不同工作频率下直接分析传感器性能。我们的研究结果表明,传感器的谐振频率会影响测量的灵敏度和稳定性。较高的工作频率可确保更好的灵敏度,但会受到被吸收水分子的较大阻尼效应的影响。在给定的 RH%范围内,通过精心选择工作频率,该传感器实现了 17.4 ppm/RH%的最大测量灵敏度和低漂移。此外,该开发的传感器在频率偏移和品质因数(Q)方面的稳定性和灵敏度分别提高了 150%和 75%。最后,该传感器还可用于各种卫生应用,例如非接触式接近检测和口罩检查。