Quartz crystal microbalance sensors

A variety of chemical gas sensors are or could be used in electronic nose instruments. So far, successful results have been reached with conductive polymer (CP) sensors, metal oxide semiconductor (MOS) sensors, metal oxide semiconductor field effect transistor (MOSFET) sensors, quartz crystal microbalance (QCM) sensors, and infrared sensors. 

Piezoelectric mass deposition sensor (quartz crystal microbalance)... 

Mass sensors measure the change in mass upon interaction with the analyte. There are two main types of mass sensors quartz crystal microbalance (QCM) and surface acoustic wave (SAW). QCM measures the mass per unit area by measuring the change in frequency of a quartz crystal resonator. SAW uses a piezoelectric sensor to convert an electric signal into a mechanical wave that is then reconverted into an electric signal. Changes in amplitude, phase, frequency, or time delay between the input and output electrical signals are used to measure the concentration of the analyte. 

Acoustic Wave Sensors. Another emerging physical transduction technique involves the use of acoustic waves to detect the accumulation of species in or on a chemically sensitive film. This technique originated with the use of quartz resonators excited into thickness-shear resonance to monitor vacuum deposition of metals (11). The device is operated in an oscillator configuration. Changes in resonant frequency are simply related to the areal mass density accumulated on the crystal face. These sensors, often referred to as quartz crystal microbalances (QCMs), have been coated with chemically sensitive films to produce gas and vapor detectors (12), and have been operated in solution as Hquid-phase microbalances (13). A dual QCM that has one smooth surface and one textured surface can be used to measure both the density and viscosity of many Hquids in real time (14). 

Bulk and surface imprinting strategies are straightforward tools to generate artificial antibodies. Combined with transducers such as QCM (quartz crystal microbalance), SAW (surface acoustic wave resonator), IDC (interdigital capacitor) or SPR (surface plasmon resonator) they yield powerful chemical sensors for a very broad range of analytes. 

The quartz crystal microbalance has a long history of application as a means of determining film thickness in vacuum deposition techniques and more recently as a means of detecting trace constituents in the gas phase. In essence, it is an extremely sensitive sensor capable of measuring mass changes in the nanogram range. 

Spangler B.D., Wilkinson E.A., Murphyb J.T., Tyler B.J., Comparison of the Spreeta surface plasmon resonance sensor and a quartz crystal microbalance for detection of Escherichia coli heat-labile enterotoxins, Analytica Chimica Acta 2001 444 149-161. 

F. Caruso, E. Rodda, D.F. Furlong, K. Niikura, and Y. Okahata, Quartz crystal microbalance study of DNA immobilization and hybridization for nucleic acid sensor development. Anal. Chem. 69, 2043-2049 (1997). 

J.Q. Hu, F.R. Zhu, J. Zhang, and H. Gong, A room temperature indium tin oxide/quartz crystal microbalance gas sensor for nitric oxide, Sens. Actuators B, 93 175-180, 2003. 

Quartz crystal microbalances (QCMs), in acoustic wave sensors, 22 270 sensors, 23 708... 

Slip is not always a purely dissipative process, and some energy can be stored at the solid-liquid interface. In the case that storage and dissipation at the interface are independent processes, a two-parameter slip model can be used. This can occur for a surface oscillating in the shear direction. Such a situation involves bulk-mode acoustic wave devices operating in liquid, which is where our interest in hydrodynamic couphng effects stems from. This type of sensor, an example of which is the transverse-shear mode acoustic wave device, the oft-quoted quartz crystal microbalance (QCM), measures changes in acoustic properties, such as resonant frequency and dissipation, in response to perturbations at the surface-liquid interface of the device. 

B. D. Spangler,E. A. Wilkinson, J. T. Murphy, and B. J. Tyler, "Comparison of the Spreeta Surface plasmon Resonance Sensor and a Quartz Crystal Microbalance for Detection of Escherichia Coh heat-labile Enterotoxin," Analytica Chimica Acta 444, 149-161 (2001). 

Rei, Z. Larsson, R. Aastrup, T. Anderson, H. Lehn, J.-M. Ramstrom, O. Quartz crystal microbalance bioaffmity sensor for rapid identification of... 

S.J. LASKY and D.A. BUTTRY, "Sensors Based on Biomolecules Immobilized on the Piezoelectric Quartz Crystal Microbalance", ACS Symp. Ser. 403 (1989) 183. 

Figure 15.7 Response of the molecular imprinted polymer quartz crystal microbalance (MIP-QCM) sensor to monoterpene analogues ( ) L-menthol, (A) D-menthol, ( ) citronel-lol, (A) citronellal, and (O) menthone. Reprinted from Percival et al. (2001). Copyright 2001 American Chemical Society.

Fig. 15.10 Discrimination of hop varieties with six quartz crystal microbalance (QMB) sensors with 12 (a) and 50 (b) measurements per sample. N Nugget, S Select, M Magnum, P Perle, T Tradition, B Northern Brewer...

MOS metal oxide sensor, MOSFET metal oxide semiconductor field-effect transistor, IR infrared, CP conducting polymer, QMS quartz crystal microbalance, IMS ion mobility spectrometry, BAW bulk acoustic wave, MS mass spectrometry, SAW siuface acoustic wave, REMPI-TOFMS resonance-enhanced multiphoton ionisation time-of-flight mass spectrometry... 

This is the correct name for most popular mass sensors, although they are better known as Quartz Crystal Microbalances (QCMs). A piezoelectric crystal vibrating in its resonance mode is a harmonic oscillator. For microgravimetric applications, it is necessary to develop quantitative relationships between the relative shift of the resonant frequency and the added mass. In the following derivation, the added mass is treated as added thickness of the oscillator, which makes the derivation more intuitively accessible. 

Although less common, some third-order chemical sensors have found significant applications not only in sensing but also in research. One such example is Electrochemical Quartz Crystal Microbalance (EQCM). With EQCM, an electrochemical experiment can be performed in its inherently large experimental space, that is, various electrochemical waveforms, impedance analysis, gating, and different mass loading. As the dimensionality of the experiment is increased, so is its information content. 

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