Acoustic wave microsensors. Part II (original) (raw)
Related papers
Applications of Acoustic Wave Devices for Sensing in Liquid Environments
Applied Spectroscopy Reviews, 2006
Acoustic wave devices such as thickness shear mode (TSM) resonators and shear horizontal surface acoustic wave (SH-SAW) devices can be utilized for characterizing physical properties of liquids and for chemical sensor applications. Basic device configurations are reviewed and the relationships between experimental observables (frequency shifts and attenuation) and physical properties of liquids are presented. Examples of physical property (density and viscosity) determination and also of chemical sensing are presented for a variety of liquid phase applications. Applications of TSMs and polymer-coated guided SH-SAWs for chemical sensing and uncoated SH-SAWs for "electronic tongue" applications are also discussed.
Guided Acoustic wave sensors for liquid environments
Journal of Physics D: Applied Physics
Surface acoustic wave (SAW) based sensors for applications to gaseous environments have been widely investigated since the last 1970s. More recently, the SAW-based sensors focus has shifted towards liquid-phase sensing applications: the SAW sensor contacts directly the solution to be tested and can be utilized for characterizing physical and chemical properties of liquids, as well as for biochemical sensor applications. The design of liquid phase sensors requires the selection of several parameters, such as the acoustic wave polarizations (i.e., elliptical, longitudinal and shear horizontal), the wave-guiding medium composition (i.e., homogeneous or non-homogeneous half-spaces, finite thickness plates or composite suspended membranes), the substrate material type and its crystallographic orientation. The paper provides an overview of different types of SAW sensors suitable for application to liquid environments, and intents to direct the attention of the designers to combinations of materials, waves nature and electrode structures that affect the sensor performances.
Hydrogen Bond Acidic Polymers for Surface Acoustic Wave Vapor Sensors and Arrays
Analytical Chemistry, 1999
Four hydrogen bond acidic polymers are examined as sorbent layers on acoustic wave devices for the detection of basic vapors. A polysiloxane polymer with pendant hexafluoro-2-propanol groups and polymers with hexafluorobisphenol groups linked by oligosiloxane spacers yield sensors that respond more rapidly and with greater sensitivity than fluoropolyol, a material used in previous SAW sensor studies. Sensors coated with the new materials all reach 90% of full response within 6 s of the first indication of a response. Unsupervised learning techniques applied to pattern-normalized sensor array data were used to examine the spread of vapor data in feature space when the array does or does not contain hydrogen bond acidic polymers. The radial distance in degrees between pattern-normalized data points was utilized to obtain quantifiable distances that could be compared as the number and chemical diversity of the polymers in the array were varied. The hydrogen bond acidic polymers significantly increase the distances between basic vapors and nonpolar vapors when included in the array.
Acoustic wave sensors: design, sensing mechanisms and applications
Smart Materials and Structures, 1997
Acoustic waves are currently being used in a wide range of sensor fields including physical sensing, chemical sensing and biosensing. Their implementation requires specific knowledge of materials, acoustic wave properties, device design and the sensing mechanisms involved for a wide range of applications. In this paper, the authors report on commonly used acoustic wave devices in sensor applications as well as the design techniques and fabrication processes. Sensing mechanisms and a portable sensor array system are described. The development of IC-based processes, thin-film deposition and sensitive layer fixation will allow for the integration of a total physical and chemical analysis system in the one IC package, leading to the evolution of smart sensors.
Analytical Chemistry, 1992
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Sensing Materials for Surface Acoustic Wave Chemical Sensors
Progresses in Chemical Sensor, 2016
Online real-time monitoring of gases requires a miniaturized, passive, and accurate gas sensor. Surface acoustic wave (SAW) devices possess these properties which make them suitable for gas-sensing applications. They have shown remarkable results in sensing of different gases in terms of sensitivity, selectivity, response, and recovery times. One of the important prerequisites a designer should know is to have knowledge on the different types of sensing material suitable for gas-sensing applications, prior to design and fabrication of the sensor. Different sensing materials, including metal oxides, polymers, carbon nanotubes, graphene, nanocomposites, etc. have been used for SAW gas sensors. In this article, different sensing materials for SAW gas sensors will be discussed.
Interfacial properties and the response of the thickness-shear-mode acoustic wave sensor in liquids
Langmuir, 1993
The behavior of the piezoelectric acoustic wave sensor of the thickness-shear-mode type in various liquids has been characterized by the network analysis method. Models for this system based only on bulk liquid parameters fail to explain the behavior of the device with respect to series resonant frequency. Use of sensors with controlled surface free energy of the metal electrodes has been employed to demonstrate the importance of the liquid-solid interface in determining the response of the device. The contribution of the effects of surface roughness on the sensor response is discussed. Additionally, a previously-published four-layer model is successful in predicting the trends in values for the series resonant frequency for a set of mixed water-methanol solutions.