Gu Xiyu, Liu Yan, Qu Yuanhang, Chen Xiang, Liu Zesheng, Cai Yao, Liu Wenjuan, Guo Shishang, Sun Chengliang
Key Laboratory of Artificial Micro, and Nano-structures of Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan, 430072, PR China.
School of Mathematical and Physical Sciences, Wuhan Textile University, Wuhan, 430200, PR China.
Microsyst Nanoeng. 2024 Oct 11;10(1):143. doi: 10.1038/s41378-024-00790-6.
The high-frequency and high-quality factor characteristics of bulk acoustic wave (BAW) resonators have significantly advanced their application in sensing technologies. In this work, a fluidic sensor based on a BAW resonator structure is fabricated and investigated. Embedded microchannels are formed beneath the active area of the BAW device without the need for external processes. As liquid flows through the microchannel, pressure is exerted on the upper wall (piezoelectric film) of the microchannel, which causes a shift in the resonant frequency. Using density functional theory, we revealed the intrinsic mechanism by which piezoelectric film deformation influences BAW resonator performance. Theoretically, the upwardly convex piezoelectric film caused by liquid flow can increase the resonant frequency. The experimental results obtained with ethanol solutions of different concentrations reveal that the sensor, which operates at a high resonant frequency of 2.225 GHz, achieves a remarkable sensitivity of 5.1 MHz/% (221 ppm/%), with an ultrahigh linearity of 0.995. This study reveals the intrinsic mechanism of liquid sensing based on BAW resonators, highlights the potential of AlN/AlScN composite film BAW resonators in liquid sensing applications and offers insights for future research and development in this field.
体声波（BAW）谐振器的高频和高品质因数特性极大地推动了其在传感技术中的应用。在这项工作中，制备并研究了一种基于BAW谐振器结构的流体传感器。在BAW器件的有源区下方形成嵌入式微通道，无需外部工艺。当液体流过微通道时，压力作用在微通道的上壁（压电薄膜）上，导致谐振频率发生偏移。利用密度泛函理论，我们揭示了压电薄膜变形影响BAW谐振器性能的内在机制。理论上，液体流动引起的向上凸起的压电薄膜会增加谐振频率。用不同浓度乙醇溶液获得的实验结果表明，该传感器在2.225 GHz的高谐振频率下工作，灵敏度高达5.1 MHz/%（221 ppm/%），线性度超高，为0.995。本研究揭示了基于BAW谐振器的液体传感内在机制，突出了AlN/AlScN复合薄膜BAW谐振器在液体传感应用中的潜力，并为该领域未来的研究与发展提供了思路。
