Design and Fabrication of a Surface Acoustic Wave Device for Bio/Chemical Applications
In this work, we report on the design and fabrication of a surface acoustic wave device, SAW sensors use piezoelectric materials to generate acoustic waves. With the help of the interdigitated transducers on the piezoelectric material, applying a voltage at the input IDT causes an acoustic wave that propagates through the substrate and at the output is converted to an electrical signal which is readable. To actualize a SAW sensor for bio/chemical sensing applications the following were studied and developed: i) Detection of stable and sensitive sensing materials, ii) Integration of sensing layers and gas testing using a dual QCM sensor, iii) Testing the fabricated SAW device. The synthesis and performance evaluation of electrosprayed multi-walled carbon nanotubes (MWCNTs) sensing layers for gas detection of volatile organic compounds were carried out. MWCNTs are characterized by a hollow structure, large surface area, and several unique properties that make them potentially excellent for gas sensing.However, to improve the sensitivity, stability, and reproducibility effects of the carbon nanotubes, they were doped with PVDF polymer in a minimal concentration such that it utilizes its strong binding effect with interconnected nanotubes and the substrate. We further ensured that the inclusion of the polymer as a binder does not affect the dominance of the MWCNTs on the surface as observed from SEM characterization. The electrospray deposition technique, combined with sonication, was used to ensure the MWCNT was dispersed evenly in the polymer matrix, as MWCNTs tend to aggregate due to their strong Van der Waals forces. The synthesized MWCNT and MWCNT/PVDF films were coated onto a Quartz Crystal Microbalance (QCM) sensor as a chemically interactive sensing material. The QCM sensors are widely used acoustic sensors for practical applications due to their ease of measurement and high sensitivity. The sensing mechanism and the kinetic adsorption of gases on the sensors were studied and the experimental result shows that MWCNT-OH/PVDF sensor revealed a larger sensitivity than that of the MWCNT-OH sensor to tested volatile organic compounds at room temperature.
Materials science|Computer Engineering
"Design and Fabrication of a Surface Acoustic Wave Device for Bio/Chemical Applications"
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