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Polymerization of Natural Oils for a Quartz Crystal Microbalance-Based Gas Sensor Application
Published in Chin Hua Chia, Chin Han Chan, Sabu Thomas, Functional Polymeric Composites, 2017
Rashmi.T.A. Das, Panchan.A.N. Pramanik, Raj.I.B. Bandyopadhyay
The Sauerbrey equation is only strictly applicable to uniform, rigid, thin-film deposits. However, liquid phase QCM measurements have been done from the beginning of 1980s. The oscillating frequency of a piezoelectric crystal decreases with the adsorption of any substances on the surface. Theoretically, the detection limit of oscillating quartz crystals is about 10−12 g. The QCM has large applications for trace amounts of gas detection, immunosensors, DNA biosensors, and drug analysis.56 The adsorption of antibodies is a method which is widely used in the detection of various analytes,57–60 which offers a high affinity and specific binding site.
Thin Films
Published in Yip-Wah Chung, Monica Kapoor, Introduction to Materials Science and Engineering, 2022
There are two methods to monitor the film thickness or deposition rate in real time. Both methods are applicable to other PVD techniques such as sputtering as discussed later in this chapter: Ionization gauge: Within the ionization gauge is a hot filament from which electrons are extracted to ionize evaporated atoms passing through the ionization gauge (Figure 10.6). A collector electrode collects and measures the resulting ion current, which gives the evaporation rate with proper calibration. Quartz crystal microbalance: A quartz crystal is a piezoelectric material and can be set into resonant vibration. When atoms are deposited onto a quartz crystal, its mass increases, causing the resonance frequency to decrease. Assume that the deposited material is uniformly distributed and rigidly attached onto the quartz crystal. The change in resonance frequency ∆f is related to the mass of materials deposited on the quartz crystal by the Sauerbrey equation: Δf=−2fo2ρμ(ΔmA)=−Cf(ΔmA)
Electrochemical Quartz Crystal Microbalance Studies of Electroactive Surface Films
Published in Arthur T. Hubbard, The Handbook of Surface Imaging and Visualization, 2022
Stanley Bruckenstein, A. Rober Hillman
The Sauerbrey equation (Equation (9.1)), which indicates a linear relationship between changes in crystal resonant frequency and changes in electrode-film mass, is based upon the assumption that surface films are rigidly coupled to the electrode surface. When this is not the case, the frequency response is determined by the viscoelastic characteristics of the system. Theoretical treatments of this situation have appeared,44,45 in which the frequency response is predicted as a function of the electromechanical properties and thickness of the surface-attached film.
Quartz crystal microbalance-based method to study adsorption of endocrine disruptor compounds on zeolite
Published in Environmental Technology, 2021
Wei-Ming Li, Yu-Jiao Tang, Lin Chen, You-Peng Chen, Peng Yan
Some dielectric materials can have an electrical field induced across its boundaries when an external force is applied. Conversely, the application of an electric field around the material can cause deformation of the dielectric. This phenomenon, known as piezoelectric effect, is often exploited in sensors [26]. The operation of QCMs utilizes the piezoelectric properties of quartz. By applying alternating current (AC) between quartz plates mounted on two metal electrodes, the resonance is excited when AC approaches the fundamental frequency of the quartz sensor. The detected harmonic frequency will be changed due to the changes in the sensor surface’s load [27]. The quantities directly generated by QCM are harmonic frequency and energy dissipation. A quantitative relationship is needed to reflect the response of QCM and the change of interface. Sauerbrey demonstrated in 1956 that the relationship between the mass uptakes (Δm) and frequency shift in the gas phase can be expressed by the Sauerbrey equation [28] presented here as Equation (1). where f0 is the fundamental frequency of the quartz crystal microbalance (MHz) and ρQ is the density of the quartz crystal (g·cm−3). Δm is the quality change of the electrode surface (g); μQ is the shear modulus; and A is the reaction area of quartz crystal (cm2).
In situ characterizations for EPS-involved microprocesses in biological wastewater treatment systems
Published in Critical Reviews in Environmental Science and Technology, 2019
Peng Zhang, Bo Feng, You-Peng Chen, You-Zhi Dai, Jin-Song Guo
The traditional QCM technique is based on the piezoelectric effect, i.e., when an AC voltage is applied to a quartz crystal, it continuously oscillates according to the natural frequency if the resonant frequency of the quartz is close to the voltage frequency. The Sauerbrey equation describes the quantitative relationship between the surface quality changes of the quartz crystal and the frequency change of the quartz crystal. The QCM has come into apply in the aqueous phase until the emergence of QCM-D. QCM-D can determine the changes in the mass and the structure of the macromolecule on the surface, which supplies information on the macromolecule behavior at the interface, especially on the solid-liquid interface. The quantification level on the sensing surface reaches as low as ∼ ng/cm2.