SAW based phononic crystal sensor, technological challenges and solutions
SAW based phononic crystal sensor, technological challenges and solutions
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DOI：
10.1007/s00542-015-2781-3
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发表时间：
2016-07-01
影响因子：
2.1
通讯作者：
Hirsch, Soeren
中科院分区：
文献类型：
--
作者：
Schmidt, Marc-Peter;Oseev, Aleksandr;Hirsch, Soeren
最近引入了具有专门设计的液体填充缺陷的声子晶体 (PnC) 作为一种新型传感器平台（Lucklum 等人，发表于 Sens Actuators B Chem 171-172:271-277, 2012）。基于这一原理的传感器具有覆盖被测量典型输入范围的带隙以及带隙内的窄传输峰值，其中最大传输频率由被测量控制。该方法已应用于确定液体的体积特性（Lucklum 等人，在 Sens Actuators B Chem 171-172:271-277, 2012 中；Oseev 等人，在 Sens Actuators B Chem 189:208-212, 2013 中；Lucklum 和 Li 在 Meas Sci Technol 20(12):124014 中， 2009）并表现出有吸引力的敏感性。提高灵敏度的一种方法需要 100 MHz 及以上范围内的更高探测频率。在此范围内，表面声波 (SAW) 器件是传感器的既定基础。我们已经对 PnC 微传感器进行了首次测试（Lucklum 等人，《走向基于 SAW 的声子晶体传感器平台》。见：2013 年联合欧洲频率和时间论坛及国际频率控制研讨会 (EFTF/IFC)，第 69-72 页，2013 年）。 PnC SAW 传感器的相应特征尺寸的尺寸范围为 10 A μm 及以下。尽管这些尺寸是常见 MEMS 材料的现有技术，但在具有纵横比直径/深度的压电材料中蚀刻孔和腔仍然具有挑战性。在这篇文章中，我们描述了一种改进的技术流程，能够在 SAW 基板上实现相当深且均匀的孔。
Phononic crystals (PnC) with a specifically designed liquid-filled defect have been recently introduced as a novel sensor platform (Lucklum et al. in Sens Actuators B Chem 171-172:271-277, 2012). Sensors based on this principle feature a band gap covering the typical input span of the measurand as well as a narrow transmission peak within the band gap where the frequency of maximum transmission is governed by the measurand. This approach has been applied for determination of volumetric properties of liquids (Lucklum et al. in Sens Actuators B Chem 171-172:271-277, 2012; Oseev et al. in Sens Actuators B Chem 189:208-212, 2013; Lucklum and Li in Meas Sci Technol 20(12):124014, 2009) and has demonstrated attractive sensitivity. One way to improve sensitivity requires higher probing frequencies in the range of 100 MHz and above. In this range surface acoustic wave (SAW) devices are an established basis for sensors. We have performed first tests towards a PnC microsensors (Lucklum et al. in Towards a SAW based phononic crystal sensor platform. In: 2013 Joint European frequency and time forum and international frequency control symposium (EFTF/IFC), pp 69-72, 2013). The respective feature size of the PnC SAW sensor has dimensions in the range of 10 A mu m and below. Whereas those dimensions are state of the art for common MEMS materials, etching of holes and cavities in piezoelectric materials that have an aspect ratio diameter/depth is still challenging. In this contribution we describe an improved technological process able to realize considerably deep and uniform holes in a SAW substrate.