Resonator bulk wave

Resonant bulk wave devices Si02, LiTa03... 

Resonant bulk wave devices SiOj, LiTaOs... 

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. 

Bnlk wave devices have different tolerances and recently Capelle, Zarka and co-workers have studied bulk waves in qnartz resonators and used stroboscopy to identify unwanted modes associated with defects. They have also performed tine section topography in stroboscopic mode to identify if the interaction between a dislocation and the acoustic wave could be described by simple linear piezoelectric theory. Using simulation of the section topographs to analyse the data, they conclnded that a non-Unear interaction was present near to the dislocation line, linear theory working satisfactorily in the region far from the defect. Etch channels appeared to have more inflnence on the acoustic wave than individnal dislocations. 

On the transducer side, there have been more recent developments like the Lamb oscillator or the so-called film bulk acoustic resonators (FEAR). Lamb wave devices are related to SAW in terms of using interdigitated structures for transduction. The difference, however, is that in a Lamb wave resonator not only the surface, but the entire bulk of the device oscillates. This makes it much less sensitive against viscous damping. FEAR on the other hand consist of a metal/aluminium nitride/metal sandwich, where bulk waves (thickness oscillations) are induced in the AIN material. Eoth these devices have in com-... 

Because only acoustic waves at specific frequencies can efficiently propagate between the faces of bulk wave crystals, these devices are electronically used as frequency filters and the frequency-determining elements in oscillator circuits. As filters, bulk wave crystals will only pass electrical signals occurring over narrow frequency ranges centred about each resonant frequency. Additional frequency-selective circuitry is typically used to limit signal transmission to the... 

A mathematical relationship between the mass of material placed upon a bulk wave resonator and frequency shift (equation 14.14) was first derived by Sauerbrey (4) ... 

If a viscous medium is placed at the surface of a bulk wave resonator, the acoustic wave will extend into the viscous layer but will be damped. The damping constant will be (12,13) ... 

Equation (14.19) is applicable to the case where a thick layer of a liquid is placed atop the resonator surface. Physically, it predicts that only a thin layer of liquid will undergo displacement at the surface the bulk wave device, and device response will be a function of the mass of this layer. Bruckenstein has observed that the response of a resonator which has both an elastic solid deposited layer and liquid atop the surface will be a linear sum of the responses expected for each individual perturbation (12). 

An expression for the resonant frequency of a bulk wave device having a viscous and elastic deposited layer has not been derived in any simplified form. The frequency can, however, be obtained by numerical solution of Kanzawa s general viscoelastic solution to the wave equations given below (14) ... 

Unfortunately, much of the theoretical basis for predicting resonator response to different types of mass loading conditions has only recently been developed. As a result many mass sensing and chemical sensing applications were developed within the confines of the expected Sauerbrey equation response. Nevertheless, a broad range of mass and chemical sensing applications has been illustrated using the bulk wave resonator. This work will be discussed in the applications section (14.5) of this chapter. 

Applications of piezoelectric sensors operating completely in the presence of a liquid have to date fallen into three categories measurement of the rheological properties of a liquid, electrochemical studies, and bioassays. Kanazawa (13, 14) and Bruckensfein (12), working independently, both developed the theory to predict resonant frequency shifts of a bulk wave device in the presence of a liquid, and both found that responses could be used to measure liquid density and viscosity. In related work, Martin (71,77) has shown that the attenuation of a surface-skimming bulk wave on an SAW device can be used as an indication of liquid viscosity. 

The above studies suggest that while mass loading in the presence of a liquid can be observed with both types of piezoelectric sensors, simultaneous changes in the viscosity of the liquid at the surface or of the material bound to the surface may complicate the response of a bulk wave device to a greater extent. For a SAW device, Martin found that signal attenuation was a more sensitive measure of liquid viscosity than wave velocity (or resonant frequency) change (71,77). This observation has a theoretical basis, because it is known that acoustic wave attenuation due to viscosity losses has only a second-order effect on the phase velocity of the wave (83). 

Bulk waves, surface waves, and waves of other types (see Section 28.2.3.3.3) are associated with characteristic resonance frequencies correspond-... 

Smythe R, Helmbold RC, Hague GE, Snow KA (2000) Langasite, langanite, and langatate bulk-wave Y-cut resonators. IEEE Trans Ultrason Eerroelectr Ereq Control 47 355-360... 

If the wave propagates through the substrate, the wave is called a bulk wave. The most commonly used BAW devices are the thickness shear mode (TSM) resonator and the shear-horizontal acoustic plate mode (SH-APM) sensor. The TSM, also widely referred to as a quartz crystal microbalance (QCM), is the best-known and simplest... 

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. 

A schematic diagram of a bulk acoustic wave (BAW) chemical sensor is composed of a BAW piezoelectric resonator with one or both surfaces covered by a membrane (CIM) (fig. 14). 

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. 

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... 

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