Surface acoustic wave sensor applications

Shiokawa S. and Kondoh J., Surface acoustic wave sensor for liquid-phase application, presented at IEEE Ultrasonics Symposium, October 17-20, 1999, Caesars Tahoe, NV, USA. 

The combination of molecularly imprinted polymers and europium signal transduction has proven applicable as a generic scheme to develop materials for the detection of hydrolyzed and non-hydrolyzed organophosphate containing cong>ounds such as pesticides and nerve agents. These polymers can be coated onto optical fibers and used as sensors for the detection of these species in aqueous environments. Similar functional polymers can also be used for enhancing the sensitivity and selectivity of other detection devices such as surface acoustic wave sensors. 

Afzal A, Dickert FL (2011) Surface acoustic wave sensors for chemical applications. In Korotcenkov G (ed) Chemictd sensors comprehensive sensor technologies, vol 3, Solid state devices. Momentum Press, New York, pp 447-484... 

Chung CK, Chang YL, Wu JC, Jhu JJ, Chen TS (2009) Characterization and patterning of novel high-TCR Ta-Si-N thin films for sensor application. Sens Actuators A 156 323-327 Cobitmu C, Geotgescu I, Buiculescu V (2007) Chip level packaging for wireless surface acoustic wave sensor. US patent 0114889 A1... 

Afzal A, Dickert FL (2011) Surface acoustic wave sensors for chemical applications. In Korotcenkov G (ed) Chemical sensors comprehensive sensor technologies, vol 4, Solid state devices. Momentum, New York, pp 447-484 Ameloot R, Stappers L, Fransaer J, Alaerts L, Sels BF, De Vos DE (2009) Patterned growth of metal-organic framework coatings by electrochemical synthesis. Chem Mater 21 2580-2582 Ballantine DS, Wohltjen H (1989) Surface acoustic wave devices for chemical analysis. Anal Chem 61 704-715 Ballantine DS Jr, White RM, Martin SJ, Ricco AJ, Zellers ET, Frye GC, Wohltjen H (1996) Acoustic wave sensors theory, design, and physico-chemical applications. In Levy M, Stem R (eds) Applications of modern acoustics. Academic, San Diego... 

The major piezoelectric applications are sensors (pickups, keyboards, microphones, etc.), electromechanical transducers (actuators, vibrators, etc ), signal devices, and surface acoustic wave devices (resonators, traps, filters, etc ). Typical materials are ZnO, AIN, PbTiOg, LiTaOg, and Pb(Zr.Ti)03 (PZT). 

Macrocyclic Compounds in Analytical Chemistry. Edited by Yury A. Zolotov Surface-Launched Acoustic Wave Sensors Chemical Sensing and Thin-Film Characterization. By Michael Thompson and David Stone Modern Isotope Ratio Mass Spectrometry. Edited by T. J. Platzner High Performance Capillary Electrophoresis Theory, Techniques, and Applications. Edited by Morteza G. Khaledi... 

There are several applications of ZnO that are due to its excellent piezoelectric properties [28,164]. Examples are surface-acoustic wave (SAW) devices and piezoelectric sensors [28,165-167]. Typically, SAW devices are used as band pass filters in the tele-communications industry, primarily in mobile phones and base stations. Emerging field for SAW devices are sensors in automotive applications (torque and pressure sensors), medical applications (chemical sensors), and other industrial applications (vapor, humidity, temperature, and mass sensors). Advantages of acoustic wave sensors are low costs, ruggedness, and a high sensitivity. Some sensors can even be interrogated wirelessly, i.e., such sensors do not require a power source. 

Devices based on piezoelectric crystals, which allow transduction between electrical and acoustic energies, have been constructed in a number of conrigurations for sensor applications and materials characterization. This cluqtter examines those devices most commonly utilized for sensing a( licatithickness-shear mode (TSM) resonator, the surface acoustic wave (SAW) device, the acoustic plate mode (APM) device, and the flexural plate wave (FPW) device. Each of these devices, shown schematically in Figure 3.1, uses a unique acoustic mode. 

Another important area where gold-thiol monolayers might find promising applications is gas- and biosensing. Simple sensors sensitive to certain types of compounds, based on such detection methods as surface plasmon resonance or surface acoustic wave, have been described454,455,531-533. This type of device is usually made of a gold plate coated with a functionalized monolayer. The terminal functional group of such a monolayer is responsible for selective interactions with the analyte, and adsorption of the latter is then detected by the appropriate method. 

There are some excellent review articles on different aspects of mesostructured materials, such as synthesis, properties, and applications. " Extensive research effort has been devoted to the exploitation of new phases (lamellar, cubic, hexagonal structures), expansion of the pore sizes (about 2-50 nm are accessible), and variable framework compositions (from pure silica, through mixed metal oxides to purely metal oxide-based frameworks, and inorganic-organic hybrid mesostructures). Another research focus is on the formation of mesostructured materials in other morphologies than powders, e.g. monolithic materials and films, which are required for a variety of applications including, but not limited to, sensors (based on piezoelectric mass balances or surface acoustic wave devices), catalyst supports, (size- and shape-selective) filtration membranes or (opto)electronic devices. The current article is focused... 

Perturbations of the medium adjacent to the device surface result in variations in the phase, amplitude, and velocity of the surface acoustic wave. Specifically, these properties will be affected by changes in the density, viscosity, or elastic properties of the medium in contact with the surface. Since the acoustic wave has an electric potential wave associated with it as well, the SAW can also be used to probe the dielectric and conductive properties of this surface medium. By far, the largest number of chemical sensor applications of SAW devices take advantage of the mass sensitivity of SAW oscillators. 

A coated surface-acoustic-wave (SAW) sensor capable of real-time, selective measurement of vinyl acetate vapor in the presence of several olefin and non-olefin cocontaminants is described. The coating film en loyed consists of the solid platinum-ethylene Ji-complex, trans-PtCl (ethylene)(pyridine). occluded in a polyisobutylene matrix. Exposure to vinyl acetate results in displacement of ethylene from the cott lex and formation of the vinyl acetate-substituted complex. Subsequent regeneration of the original reagent is possible by treatment with ethylene gas, in situ. A lower detection limit of 5 ppm of vinyl acetate is achieved for operation at 46 C. The industrial-hygiene applications of the sensor are discussed. 

The response of piezoelectric devices propagating shear horizontal acoustic plate modes (SH-APMs) has been modeled and experimentally characterized for variations in surface mass, liquid rheological properties, and solution dielectric coefficient and electrical conductivity. The nature of the SH-APM and its propagation characteristics are outlined and used to describe a range of Interactions at the solid/liquid interface. Sensitivity to sub-monolayer mass changes is demonstrated and a Cu sensor is described. The APM device is compared to the surface acoustic wave device and the quartz crystal microbalance for liquid sensing applications. 

Chemical sensors based on acoustic wave (AW) devices have been studied for a number of sensing applications, the majority of which fall in the category of gas and vapor detection (1-8). Recently, the use of these sensors in liquid environments has been explored (9-13). AW sensors utilize various types of acoustic waves, including the surface acoustic wave (SAW), the shear-horizontal acoustic plate mode (SH-APM) (10-13), and the Lamb wave (also a plate mode) (3.14). Even though most studies of these piezoelectric sensors have centered on SAW devices (1.2.4-8), differences in the propagation characteristics of the various acoustic modes make some better suited than others for a given sensing application. 

The observed glass transition temperatures (T ) of several thin polymer films on surface acoustic wave (SAW) devices are 50-60 °C higher than the results reported using other methods such as DSC. The increase in the onset of T is the result of interaction of the high frequency SWJ with the polymer film, consistent with the time-temperature superposition principle. The Tj were identified as localized minima in the frequency curves, or by changes in the slope of the curves, as the coated sensors were heated between 35-110 °C. Potential applications of SAWs for the characterization of polymer materials and the Implications of these findings for the interpretation of SAW data are discussed. 

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