Research Initiation Awards: In-Situ Measurement of Interfacial Mass Changes with Chemically Milled At-cut Quartz Crystals

压电式换能器因其能够检测微小的界面质量变化而被开发。石英晶体微天平(QCM)由夹在两个金属激发电极之间的AT切石英薄片组成，在这方面得到了广泛的应用。QCM的形式特别吸引人，因为AT-Cut石英晶体价格低廉，易于操作，并且可以配置为使其中一个激励电极可以用作传统电化学电池的工作电极。然而，由于QCM的工作频率相当低(0.10 MHz)，与其他换能器相比，QCM的灵敏度较低，这在一定程度上限制了QCM的应用。该计划旨在通过研究在蒸气和液体介质中使用高频(高达100 MHz)、小型化学研磨AT-Cut石英晶体进行质量检测来消除这一障碍。本项目的目标将是证明(1)这些晶体对金属沉积和气体分析物在薄膜活性薄膜中的吸附的质量敏感性，(2)这些器件在液体介质中的生存能力和质量敏感性(3)检测电化学诱导的质量变化，(4)使用这些谐振器的各种传感器配置的可行性；(5)使用这些晶体作为粘度传感器的可行性。

Piezoelectric transducers have been exploited for their ability to detect minute interfacial mass changes. The quartz crystal microbalance (QCM), comprising a thin wafer of AT-cut quartz sandwiched between two metallic excitation electrodes, has been used extensively in this regard. The format of the QCM is particularly attractive since AT-cut quartz crystals are inexpensive, easily handled and can be configured so that one of the excitation electrodes can be used as a working electrode in a conventional electrochemical cell. Applications of the QCM have been somewhat limited, however, by low sensitivity compared to other transducers because of the rather low operating frequencies (.10 MHz) of the QCM. This program aims to remove this obstacle by investigating the use of high frequency (up to 100 MHz), miniature chemically milled AT-cut quartz crystals in mass detection, both in vapor and liquid media. The goals this project will be to demonstrate (1) the mass sensitivity of these crystals to metal deposition and adsorption of gaseous analytes into thin active films, (2) the viability and mass sensitivity of these devices in liquid media (3) detection of electrochemically induced mass changes, (4) the feasibility of various sensor configurations using these resonators and (5) the use of these crystals as viscosity sensors.