Application Of Quartz Crystal Microbalance Research Articles

Quartz crystal resonators with atomically smooth surfaces for use in contact mechanics

A quartz crystal shear resonator was modified by gluing a thin piece of mica on one surface to obtain an acoustic sensor with a macroscopic atomically smooth area. Contact mechanics experiments with this resonator touching a half-spherical mica surface were performed at high shear rate by integrating it into a surface forces apparatus, which provides simultaneous load control and interferometric measurement of the real contact area and surface separation. The procedures for gluing mica on a quartz resonator without significant loss of its sensitivity and gluing a half-spherical mica surface are described in detail. Sensitivity issues and overtone order dependence are discussed. Although our work focuses on contact mechanics experiments, the technique is also relevant for quartz crystal microbalance applications.

Survey on mass determination with oscillating systems: Part III. Acoustic wave mass sensors for chemical and biological sensing

We will review the application of acoustic wave mass sensors in chemical and biological sensing with focus on quartz crystal microbalance and surface acoustic wave devices. In chemical sensing, it is unlikely that a single sensor will display a selective and reversible response to a given analyte in a mixture. Alternative strategies such as use of sensor arrays and sampling devices will be discussed to improve performance. We will also discuss applications of quartz crystal microbalance as biosensor in the liquid phase.

‘Missing mass’ effect in biosensor's QCM applications

Nowadays, liquid applications of quartz crystal microbalance (QCM) opened a way for in situ studies of proteins, vesicles and cells adsorbed from the solution onto the QCM surface. The sensitivity of QCM to the viscoelasticity of the adsorbed biomaterial can be a reason of the experimentally observed deviation from a linear dependence of QCM resonant frequency on mass deposition (the so-called Sauerbrey relation) and can limit its application for biosensoring. Presented here rigorous theoretical analysis explains the deviation from ideal mass response of soft overlayers in the contact with liquid. The fundamental result of the theory is the analog of Sauerbrey relation for layered viscous/viscoelastic medium which can be exploited for the correct physical interpretation of QCM experimental data in biofluids, in particular for measurements of the ‘true’ surface mass of adsorbed biomolecular films. We predict a new physical effect ‘missing mass’ of the sample in liquid phase measurements and compare the results given by our theory with QCM measurements on supported membranes.

An extended Butterworth-Van Dyke model for quartz crystal microbalance applications in viscoelastic fluid media.

An extended Butterworth-Van Dyke (EBVD) model with frequency-independent parameters for the characterization of a resonant compound formed by a quartz crystal in contact with a finite viscoelastic layer contacting a semi-infinite viscoelastic medium is extracted by analysis of the lumped element model. The formulation of the EBVD model is compared with the complete expression of the electrical admittance of the loaded quartz derived from the transmission line model (TLM). Relative deviations between them do not exceed 3% around 1% bandwidth near resonance. An extended Martin & Granstaff's model and an explicit expression for the frequency shift that supposes an extension of Kanazawa's model for viscoelastic media are obtained. An analysis of the errors associated with the extraction of shear parameters of the coating for different materials prove that, to obtain an error less than 5% in the shear parameters determination, the viscoelastic contribution, defined as the relative error in the thickness computed from the frequency shift by Sauerbrey equation, must be greater than a limit that depends on Q, which is defined as the ratio of the shear storage modulus (G') to shear loss modulus (G"). In the materials studied, polymers in the transition range or in the rubbery state with Q = 1 and 10, the viscoelastic contribution must be higher than 15% and 50%, respectively, for a 5% limit error in the shear parameters extraction. A criterion for a practical determination of the appropriate viscoelastic regimes is indicated.

Disposable HSA QCM-immunosensor for practical measurement in liquid

The application of quartz crystal microbalance (QCM) as affinity immunosensor of human serum albumin (HSA) has been investigated. The aim of the investigation was the development of a sensor for simple use for physicians in practice. The HSA immunosensors were constructed as a disposable immunosensor based on a cost effective QCM sensor. A self mixing cell without pumping system was constructed together with the QCM-immunosensor for easy handling. The HSA antibody was immobilized on top of a quartz resonator coated with a mixture of polystyrene and p- tert-butyl-calix[8]arene. There were no significant differences between the measured maximum frequency change of off-line measurement in air and on-line measurement in PBS. In this experiment, the developed immunosensor allows the measurement of HSA in PBS in the concentration range from 1 to 250 μg/ml. The limit value concentration of 20 μg/ml between ill and healthy condition can be well measured. The sensor shows a selectivity to HSA in urine.

Quartz Crystal Microbalance (QCM) used as humidity sensor

This paper describes an application of Quartz Crystal Microbalance (QCM) used as humidity sensor. Moisture apparition is detected by using a QCM associated with a Peltier module. When water condensation produced by the Peltier cooling appears on the QCM, a change of mass on the crystal sensitive surface results in the decrease of the resonant frequency. If we measure the delay time between the beginning of Peltier supply and the apparition of water condensation on the quartz, we determine the relative humidity and the condensation velocity. A study of thermal transfer is first presented. Relative humidity measurements are then realised in a climatic chamber. A theoretical approach is finally compared with the experimental results.

EQCM study of copper and iron corrosion inhibition in presence of organic inhibitors and biocides

Attention has been devoted to the application of quartz crystal microbalance (QCM) in the field of corrosion and corrosion inhibition. In-situ measurements were performed on copper and iron surfaces. Copper corrosion inhibition by the application of several inhibitors was followed by QCM. Copper corrosion inhibition in different electrolyte solutions such as acidic sodium sulphate and neutral sodium chloride were investigated. Different inhibitor compounds were tested for protection against copper corrosion. Three different groups of inhibitors were investigated; aromatic sulfoxides, benzo-hydroxamic acid derivatives, and azole derivatives. Among the tested sulfoxides, di-benzyl-sulfoxide (DBSO) produced the best protection, while p-chloro-benzo-hydroxamic acid showed excellent protection among the benzo-hydroxamic acid derivatives. Among the tested azole derivatives, 5-mercapto-1-phenyl-tetrazole (5-McPhTT) and 5-(4′-isopropylbenzylidene)-2,4-dioxotetrahydro-1,3-thiazole (5-IPBDT) showed excellent inhibition properties against copper corrosion in acidic media. The effect of biocides, namely N-hydroxyalkylated amino acids, on biofilm formation has been investigated, too. From the attained results, it is clear that QCM is an essential tool for obtaining important information on corrosion inhibition and its mechanism.

Using a quartz crystal microbalance for low energy ion beam etching studies

A quartz crystal microbalance (QCM) has been used for etching yield measurements in a low energy ion beam system. The goal is to obtain etching yields for ion energies below 150 eV for various ion chemistries and target materials. Typical beam currents are about 0.5 μA, and the mass change per unit time on the QCM is much smaller than that for typical QCM applications. A number of problems with the application of a QCM were encountered and a description of how they were overcome is presented in this article. Quantitative etch yield results for the etching of two different photoresists and SiO2 down to 25 eV ion energy are presented.

水晶振動微量天秤法の腐食研究への適用

水晶振動微量天秤法の腐食研究への適用

The Role of Longitudinal Waves in Quartz Crystal Microbalance Applications in Liquids

The generation of shear waves in liquids by the quartz crystal microbalance (QCM) is evident from the influence of liquid properties on the QCM frequency and electrical characteristics. With the exception of a few reports, contributions from longitudonal waves that arise from nonuniform velocity profiles along the shear direction or nonideal contributions from crystal longtudinal and flexure modes have been largely ignored. The presence of these longitudinal components is demonstrated by the influence of a glass plate, fixed Gel to the QCM surface at a remote distance, on the QCM resonant frequency and electrical impedance characteristics. In agreement with a previous report, these effects can be observed even when the glass plate is positioned >1 cm away from the QCM, substantially longer than the shear wave decay length. Longitudinal standing waves are evident from the periodicity of the resonant frequency, inductance, capacitance, and resistance as the distance between the QCM and the glass plate. The wavelength of the standing waves agrees with that expected for the resonant frequency of the QCM and the fluid medium. The amplitude of the standing waves depends strongly upon the quartz crystal contour, as evident from extremely large frequency excursions observed for plano-convex crystals in witch energy trapping in the center of the resonator is greater than that for plano-plano crystals. Impedance analysis indicates that the frequency excursions are primarily a consequence of changes in the capacitance of the quartz crystals that result from a decrease in the compliance of the quartz resonator due to pressure exerted by the longitudinal waves. Standing waves resulting from reflection from the fluid-air interface are also observed, although the amplitude of the standing waves is smaller than the amplitude observed with the glass reflector plate owing to the larger reflection coefficient for the latter. However, the frequency excursions that result from small changes in the height of the fluid-air interface are substantial relative to frequency changes measured in typical QCM experiments. These results demonstrate that it is important to design QCM experiments to avoid contributions from longitudinal waves

Characterization of a thickness-shear mode quartz resonator with multiple nonpiezoelectric layers

This paper describes a one-dimensional analysis of a piezoelectric resonator with multiple nonpiezoelectric layers of arbitrary thickness and complex shear modulus. This analysis shows under what conditions the simple Butterworth–Van Dyke (BVD) lumped-element equivalent circuit can be used to extract the properties of these layers, and provides a theoretical basis for doing so under these conditions. The method presented here is based on the physics of wave propagation, but uses transmission line techniques to transform the equations and boundary conditions into a simple string of 2×2 matrix multiplications, which easily accommodate any number of layers. An analysis of the AT-cut quartz/polymer/liquid composite resonator is presented in detail because of its importance in sensor and electrochemical quartz crystal microbalance applications. The analysis shows that adding the polymer and liquid impedances in the motional arm of a BVD circuit is not valid near the polymer film resonance, but is appropriate for a thin, rigid polymer film in contact with a liquid.