Memon Maria Muzamil, Liu Qiong, Manthar Ali, Wang Tao, Zhang Wanli
State Key Laboratory of Electronic Thin Films and Integrated Devices, School of Integrated Circuit Science and Engineering, University of Electronic Science and Technology of China (UESTC), Chengdu 610054, China.
School of Mechanical and Electrical Engineering, University of Electronic Science and Technology of China (UESTC), Chengdu 610054, China.
Micromachines (Basel). 2023 Apr 27;14(5):945. doi: 10.3390/mi14050945.
The Growing demands for humidity detection in commercial and industrial applications led to the rapid development of humidity sensors based on different techniques. Surface acoustic wave (SAW) technology is one of these methods that has been found to provide a powerful platform for humidity sensing owing to its intrinsic features, including small size, high sensitivity, and simple operational mechanism. Similar to other techniques, the principle of humidity sensing in SAW devices is also realized by an overlaid sensitive film, which serves as the core element whose interaction with water molecules is responsible for overall performance. Therefore, most researchers are focused on exploring different sensing materials to achieve optimum performance characteristics. This article reviews sensing materials used to develop SAW humidity sensors and their responses based on theoretical aspects and experimental outcomes. Herein the influence of overlaid sensing film on the performance parameters of the SAW device, such as quality factor, signal amplitude, insertion loss, etc., is also highlighted. Lastly, a recommendation to minimize the significant change in device characteristics is presented, which we believe will be a good step for the future development of SAW humidity sensors.
商业和工业应用中对湿度检测的需求不断增长，促使基于不同技术的湿度传感器迅速发展。表面声波（SAW）技术是其中一种方法，由于其具有体积小、灵敏度高和操作机制简单等固有特性，已被证明可为湿度传感提供强大的平台。与其他技术类似，SAW器件中的湿度传感原理也是通过覆盖的敏感薄膜实现的，该薄膜是核心元件，其与水分子的相互作用决定了整体性能。因此，大多数研究人员专注于探索不同的传感材料以实现最佳性能特征。本文基于理论方面和实验结果，综述了用于开发SAW湿度传感器的传感材料及其响应。在此还强调了覆盖传感薄膜对SAW器件性能参数（如品质因数、信号幅度、插入损耗等）的影响。最后，提出了尽量减少器件特性显著变化的建议，我们认为这将是SAW湿度传感器未来发展的良好一步。
