Piezoelectric quartz

Hydrothermal crystallisation processes occur widely in nature and are responsible for the formation of many crystalline minerals. The most widely used commercial appHcation of hydrothermal crystallization is for the production of synthetic quartz (see Silica, synthetic quartz crystals). Piezoelectric quartz crystals weighing up to several pounds can be produced for use in electronic equipment. Hydrothermal crystallization takes place in near- or supercritical water solutions (see Supercritical fluids). Near and above the critical point of water, the viscosity (300-1400 mPa s(=cP) at 374°C) decreases significantly, allowing for relatively rapid diffusion and growth processes to occur. 

A chemical microsensor can be defined as an extremely small device that detects components in gases or Hquids (52—55). Ideally, such a sensor generates a response which either varies with the nature or concentration of the material or is reversible for repeated cycles of exposure. Of the many types of microsensors that have been described (56), three are the most prominent the chemiresistor, the bulk-wave piezoelectric quartz crystal sensor, and the surface acoustic wave (saw) device (57). 

Bulk-wave piezoelectric quartz crystal sensors indirecdy measure mass changes of the coating on the surface of the sensing device. This change in mass causes changes in the resonant frequency of the device, and measurements ate based on frequency differences. 

Figure 2,108 Piezoelectric quartz crystal with vacuum-deposited electrodes. Gold is deposited on both sides of the quartz wafer a in the pattern shown. Electrical connection is made to the electrode flag b by means of a spring clip with attached lead c. The circular gold electrode in the crystal centre d opposes an identical electrode on the other side of the crystal. Electrical connection to the opposing electrode is made to the electrode flag e. Reprinted from Electrochimica Acta, 30, S. Bruckenstein and M. Shay, Experimental aspects of use of the quartz crystal micrnhalance in solution, pp. 1295-1.100 (1985), with kind permission from Pergamon Press Ltd., Headington Hill Hall, Oxford 0X3 0BW, UK.

M. Minunni, P. Skladal, and M. Mascini, A piezoelectric quartz crystal biosensor for atrazine. Life. Chem. Repts 11, 391-398 (1994). 

R.L. Bunde, EJ. Jarvi, and J.J. Rosentreter, Piezoelectric quartz crystal biosensors. Talanta 46, 1223-1236 (1998). 

S. Tombelli, M. Masdni, and A.P.F. Turner, Improved procedures for immobilisation of oligonucleotides on gold-coated piezoelectric quartz crystals. Biosens. Bioelectron. 17, 929-936 (2002). 

S. Kurosawa, E. Tawara, N. Kamo, F. Ohta, and T. Hosokawa, Latex piezoelectric immunoassay detection of agglutination of antibody-bearing latex using a piezoelectric quartz crystal. Chem. Pharm. Bull. 38,1117-1120 (1990). 

In Applications of Piezoelectric Quartz Crystal Microbalances Lu, C. Czanderna, A., Eds. Elsevier New York, 1984. 

Quite a number of recent papers have concentrated on techniques which allow the gravimetric detection of only a few femtograms of an analyte [105]. In one of these, PAHs could be measured in concentration of down to a few ng ml-1 in degraded oil when a piezoelectric quartz crystal coated with Mi-polymers imprinted either with a fresh or with a degraded lubricant was immersed into the... 

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

Park, I. S., and Kim, N. (1998). Thiolated Salmonella antibody immobilization onto the gold surface of piezoelectric quartz crystal. Biosens. Bioelectron. 13,1091-1097. 

Professor Curie continued his researches on the growth of crystals, and his young wife prepared for her examinations. Many chemists consider her dissertation (55) to be the most remarkable thesis ever presented for the doctorate. She continued the work begun by Becquerel, and tested most of the known elements, including a number of rare ones loaned by E.-A. Demarpay and Georges Urbain, with Prof. Curie s piezoelectric quartz electrometer, and found that thorium and uranium were the only ones whose compounds produced appreciable ionization (26, 54, 55). The radioactivity of thorium was discovered independently by Gerhardt Carl Schmidt, professor of physics at the University of Munster (25). 

PQCD piezoelectric quartz crystal detection/detector... 

Nitz, S., Kollmannsberger, H., Lachermeier, C., Horner, G. (1999) Odour assessment with piezoelectric quartz crystal sensor array, a suitable tool for quality control in food technology Adv. Food. Sci. 21 136-150. 

Zhao, C.Z., Pan, Y.Z., Ma, L.Z., Tang, Z.N., Zhao, G.L., Wang, L.D. (2002) Assay of fish freshness using trimethylamine vapour probe based on a sensitive membrane on piezoelectric quartz crystal. Sens. Actuators B 81 218-222. 

The scanning system is a very important part of these microscopes, and is commonly composed of a cantilever whose arms are usually made of piezoelectric quartz crystal. The electric field applied by the computer to the arms of the scanning device controls the position of the tip of the sensor to within a great spatial precision. The right variation of the electric field allows the complete scanning of the sample. 

To recover gold from electronics, see J. W. Hill and T. A. Lear, Recovery of Gold from Electronic Scrap, J. Chem. Ed. 1988,65, 802. To remove Hg from gold, soak it in a 1 1 mixture of 0.01 M (NH4)2S208 and 0.01 M HNOj [T. Nomura and M. Fujisawa, Electrolytic Determination of Mercury(II) in Water with a Piezoelectric Quartz Crystal, Anal. Chim. Acta 1986, 182, 267]. 

Fig 10. The change in resonance frequency of IX MHz. piezoelectric quartz, crystals coated with LB films of diflcrem thickness, flic molecular siruciures of the organic films are shown in Figs, fth) and ifidt... 

Film electrodes have been essential components of quartz microbalance studies of stoichiometry of many electrodeposition and dissolution experiments as well as polymer electrode characterization [25]. In the quartz microbalance, changes in mass are detected by measurement of changes in the resonant frequency of a quartz crystal oscillator as the mass adhering to the surface changes. The oscillation is feasible because thin-film metal electrodes (typically gold) applied to opposing faces of a piezoelectric quartz crystal serve both to induce the oscillation and to provide a site for electrochemical reaction. 

Shultz and King [40] reported a detector based on the piezoelectric effect. This instrument was considered to be a universal mass detector and incorporated a piezoelectric quartz sensor with which changes in mass of 0.1 ng could be detected in short periods. 

C. Lu, A. Czanderna (eds.), Applications of Piezoelectric Quartz Crystal Microbalances, Elsevier, Amsterdam, 1984. 

Mercury binding leads to an increase of mass of the gold layer which can be detected by electro-acoustic transducers based on quartz microbalance (QMB the abbreviation QCM = quartz crystal microbalance is also widely used), surface acoustic waves (SAW)—devices [20] or microcantilevers [21,22], Adsorption of mercury vapour increases resonance frequency of shear vibrations of piezoelectric quartz crystals (Fig. 12.2). This process can be described by Sauerbrey equation [23]. For typical AT-cut quartz, this equation is... 

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