Piezoelectric crystal sensors

Piezoelectric crystal sensors are passive solid-state electronic devices, which can respond to changes in temperature, pressure, and most importantly, to changes in physical properties at the interface between the device surface and a foreign fluid or solid. Such changes in physical properties include variations in interfacial mass density, elasticity, viscosity, and layer thickness. 

In recent years, the incorporation of various chemically sensitive layers has enabled the transition from the microbalance to the mass sensor and resulted in the explosive growth of piezoelectric sensors. 

This type of sensor operates by observing the propagation of an acoustic wave through the solid-state device. Sensing is achieved by correlating acoustic wave-propagation variations to the amount of analyte captured at the surface and then to the amount or concentration of analyte present in the sample exposed to the sensor, or to the changes in physical properties of interfacial thin films. 

Measurement of the frequency shift and resonant resistance change of acoustic wave is one of the most accurate types of physical measurement. The frequency and resonant resistance of piezoelectric crystal is influenced by a large number of parameters mentioned above. A selective sensor is obtained when a sensor surface is coated with selectively interacting thin film. 

Changes in physical properties are induced within a thin layer of material at one sensor surface in virtually all piezoelectric acoustic sensor applications. This thin surface layer often consists of a different material than the sensor bulk and is used to induce selective adsorption or absorption to the thin layer of an analyte of interest. 

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Carey, W.P., Beebe, K.R., Kowalski, B.R., "Multicomponent Analysis using an Array of Piezoelectric Crystal Sensors", Anal. Chem. 1987(59 1529-1534. 

When the development of a scientific field expands, the need for handbooks arises, wherein the information that appeared earlier in journals and conference proceedings is systematically and selectively presented. The sensor and actuator Held is now in this position. For this reason, Elsevier Science took the initiative to develop a series of handbooks with the name "Handbook of Sensors and Actuators" which will contain the most meaningful background material that is important for the sensor and actuator field. Titles like Fundamentals of Transducers, Thick Film Sensors, Magnetic Sensors, Micromachining, Piezoelectric Crystal Sensors, Robot Sensors and Intelligent Sensors will be part of this series. 

Ann. Occup. Hyg. Carey WP, Beebe KR, Kowalski BR. Multicomponent analysis using an array of piezoelectric crystal sensors. Anal. Chem. 1987 59 1529-34. 

FI9. 15.18 Scheme of experimental instrument for on-line measurement of SO2 with detection by a piezoelectric crystal sensor. (Reproduced from [72] with permission of the Royal Society of Chemistry). 

A recent attempt was made to develop a piezoelectric crystal sensor for nitroaromatic compounds using an (aminopropyl)triethoxy-sllane (APTES) coating (51). The selectivity was achieved by converting the silanol structure of the sllanized sensor to a slloxane structure by the interaction with water. The characteristics of Al-plated and APTES-coated sensors for several compounds are shown in Table 2. 

S.H. Si, Y.S. Fung, D.R. Zhu, Improvement of piezoelectric crystal sensor for the detection of organic vapors using nanocrystalline Ti02 films , Sensors and Actuators B Chemical, 108, 165-171, (2005). 

There is little likelihood of damage to pacemakers that have been implanted in the pectoral area however, an abdominal implant (pacemaker or ICD) is subject to damage (47, 50-52). In vitro studies have documented that pacemakers can be damaged during ESWL. If the shock wave is aimed directly at a pacemaker that employs a piezoelectric crystal sensor for rate response function, the crystal can be damaged. 

Cook RL, MacDuff RC, Sammels AF (1989) Organophosphine transition metal complexes as selective surfaces for the reversible detection of sulfur dioxide with piezoelectric crystal sensors. Anal Chim Acta 217 101-109 D Amico A, Verona E (1989) SAW sensors. Sens Actuators 17 55-66... 

Piezoelectric crystal sensors are made of tiny disks, usually quartz, lithium niobate (LiNb03) or lithium tantalite (LiTa03), coated with materials such as chromatographic... 

Besides the strain gauge type transducer, other pressure transducers may employ variable capacitance, variable inductance, or piezoelectric crystal sensors to detect pressure changes. The low level output pressure transducer can be used in systems controlling flammable and other hazardous gases if the system has been designed such that the electronic power levels being used to excite the transducer remain very low. They can even be used in Class I, Division II areas if the proper intrinsic safety barriers are used in conjunction. Like the pressure gauge, the transducer may have a... 

An older general review by Stefan et al. [2] considers mathematical modeling for data processing (including a variety of chemometric methods such as linear and nonlinear partial least squares, fuzzy neural networks, and multivariate analysis of variance), designs for electrochemical sensor arrays as well as applications in environmental, food and clinical analysis. Arrays of potentiometric ion-selective electrodes, piezoelectric crystal sensors, and voltammetric biosensors, as well as the electronic nose gas-phase sensor arrays are reviewed. 

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