Application of a Lateral Field Excited Acoustic Wave Device as a New Sensor Principle in Biointerface Analysis

Hempel, U.; Lücklum, Ralf; Hauptmann, P.

doi:10.1109/sensor.2007.4300486

Cited by 4 publications

(4 citation statements)

References 5 publications

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“…Even more pronounced results have been obtained in our own experiments with electrolytic solutions [9,10]. Moreover, it could be shown that a remarkable sensor response can be generated in the absence of any mechanical (liquid) load on top of the sensor surface simply by placing a shielding electrode, connected to ground potential, in close proximity to the bare quartz surface.…”

Section: Motivationsupporting

confidence: 54%

Quartz crystal resonator sensors under lateral field excitation—a theoretical and experimental analysis

Hempel

Lücklum

Hauptmann

et al. 2008

Meas. Sci. Technol.

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AT-cut quartz crystals have been driven with the so-called lateral field excitation. When applying a voltage to the two electrodes placed on one crystal surface and separated by a small gap an electric field is generated, which is mainly confined in the lateral direction. Extraordinary changes can be observed in the conductance spectrum when applying a liquid to the other (bare) surface of the crystal. In contrast to traditional quartz crystal sensors, these changes must be attributed to electrical properties of the adjacent medium. It is suggested that a redistribution of the exciting electric field from the lateral toward the thickness direction occurs. The assumption is supported by simulations which allow insights into the piezoelectric excitation and transduction mechanism of the acoustic device under varied electrical boundary conditions at the bare surface as well as the shear displacement patterns involved. Results from 10 MHz plano–plano and 6 MHz plano–convex sensors which have been exposed to liquids of varying permittivity show the strong dependence of the sensor response on liquid permittivity which overlies the known dependence on density–viscosity.

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Section: Motivationsupporting

confidence: 54%

Quartz crystal resonator sensors under lateral field excitation—a theoretical and experimental analysis

Hempel

Lücklum

Hauptmann

et al. 2008

Meas. Sci. Technol.

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“…The variation pattern also matched the numbers provided in Figure 8 c, which were the conductivity values measured using a portable conductivity meter. The conductivity value had a good linear relationship with the frequency shift, which was also consistent with the linear relationship exhibited by the QCM in the low concentration conductivity solution in the literature [ 16 , 36 ]. Therefore, this experiment also proved that the temperature effect had a considerable influence on the measurement of the electrical properties of QCM, and it was not possible to simply neglect the influence of the liquid viscosity and density during the measurement in the liquid.…”

Section: Resultssupporting

confidence: 89%

“…This kind of electrode structure enables the electrical field to penetrate into the liquid. Therefore, LFE-QCM has extremely high sensitivity to electrical properties in the liquid, and the mechanical properties similar to the TFE sensor [ 15 , 16 , 17 , 18 ]. At present, many studies have been completed on LFE-QCM, which has been shown to have many advantages over traditional QCM in practical applications.…”

Section: Introductionmentioning

confidence: 99%

Study on Dual Channel Lateral Field Excitation Quartz Crystal Microbalance for Measuring Liquid Electrical Properties

Liang

Kong

Liu

2019

Sensors

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Lateral field excitation quartz crystal microbalance (LFE-QCM) can detect both the electrical properties (conductivity and permittivity) and mechanical properties (viscosity and density) of the liquid. In practical applications for detecting electrical properties, the viscosity and density of the liquid will also change. This research proposed a dual-channel LFE-QCM for reducing the influence of density and viscosity. The sensing layer of one resonant element is almost bare, and the other is covered by a metal film as a reference. Different organic solutions and NaCl solution were used to study the influence of mechanical properties and the temperature on electrical properties. The experimental results demonstrate that the dual-channel LFE-QCM is necessary for properly detecting electrical properties of the liquid.

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“…In 2005, York et al 15) examined the quartz sensor in biochemical sensing and found LFE has matched or even further exceeded the QCM in the sensor parameters of reproducibility, reusability, response time, and stability. In 2007, Hempel et al 16) also presented LFE bio-sensors and assumed that liquid on the sensing surface acts as a virtual electrode to the metallic LFE electrode. In 2011, Chen and Liu 17) first presented the LFE sensor in gas sensing by finite element method, which provides the concept of this work.…”

Section: Introductionmentioning

confidence: 99%

Investigation of pseudo lateral field excited acoustic wave gas sensors with finite element method

Chen¹,

Lai²,

Hsu³

2014

Jpn. J. Appl. Phys.

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To improve the weak piezoelectric excitation of lateral field excited (LFE) acoustic wave sensors in air, a novel bulk acoustic wave device, named pseudo LFE acoustic wave sensor, is proposed in this paper. The commercially available finite element software, COMSOL Multiphysics, is adopted to analyze pseudo LFE acoustic wave gas sensors and further calculate their sensitivities to electric conductivity variation of the polyisobutylene (PIB) sensing film. An AT-cut quartz plate with a thickness of 185 µm is chosen as the piezoelectric substrate due to its tiny temperature coefficient to frequency for thickness shear mode (TSM). After the mesh convergence analysis, a mesh level is decided for following calculations. In frequency response analysis, a bare pseudo LFE sensor shows a pure TSM and a stronger excitation than a bare LFE sensor. The experiments also verify this result. In sensitivity analysis, a gradual conductivity increase of the sensing film from 0 to 3 S/m causes a significant resonance frequency decrease of the pseudo LFE sensor. Besides, the pseudo LFE sensor exhibits an excellent sensitivity to the film conductivity variation, about 30 times as high as the QCM sensor. Finally, the electrode dimensions of pseudo LFE sensors are discussed for optimizing device performances. One can find ringed floating electrodes exhibit greater sensitivity than circular ones. Moreover, a larger gap width between the LFE electrodes also contributes to larger sensitivity but weakens piezoelectric excitation. The results conclude that the pseudo LFE sensor exhibits a satisfactorily large admittance and an excellent sensitivity to external electrical fluctuation.

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Application of a Lateral Field Excited Acoustic Wave Device as a New Sensor Principle in Biointerface Analysis

Cited by 4 publications

References 5 publications

Quartz crystal resonator sensors under lateral field excitation—a theoretical and experimental analysis

Quartz crystal resonator sensors under lateral field excitation—a theoretical and experimental analysis

Study on Dual Channel Lateral Field Excitation Quartz Crystal Microbalance for Measuring Liquid Electrical Properties

Investigation of pseudo lateral field excited acoustic wave gas sensors with finite element method

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