An equivalent circuit for simulating Love mode acoustic wave transducers: comparison of simulation and results

A simulation was performed using the equivalent circuit previously developed for a Love mode surface acoustic wave transducer. The present model is based on the Mason equivalent circuit for inter-digital fingers. A Love mode SiO2/ST-cut quartz transducer with operating frequency at 96 MHz was fabricated and the transfer function and input impedance were measured. Simulation results were compared with the experimental measurements and they showed close agreement

Biosensors based on two-dimensional MoS2

The unique properties of two-dimensional molybdenum disulfide (2D MoS2) have so far led to immense research regarding this material's fundamentals, applications, and, more recently, its potential for biosensing. 2D MoS2 has properties that make it of great interest for developing biosensors. These properties include large surface area, tunable energy band diagrams, a comparatively high electron mobility, photoluminescence, liquid media stability, relatively low toxicity, and intercalatable morphologies. In this Review, the current progress on 2D MoS2 based biosensors is presented and the prospects for future possibilities of expanding its applications for a variety of biosensing applications are discussed

A ZnO/SiO2/Si(100) Love mode transducer

ZnO/SiO2/Si[100] Love mode transducers were fabricated. SiO2 films were deposited using electron beam evaporation. ZnO films were deposited using r.f. magnetron sputtering. ZnO and SiO2 films were examined by SEM and the performance of the transducers was examined by their acoustic response. The observation of the SAW Love mode delay line was performed under untuned conditions. Operating frequencies of the transducers were around 85 MHz

Vehicle cabin air quality monitor using gas sensors for improved safety

A vehicle cabin air quality monitor using carbon monoxide (CO) and oxygen (O2) gas sensors has been designed, developed and on-road tested. The continuous monitoring of oxygen and carbon monoxide provides added vehicle safety as alarms could be set off when dangerous gas concentrations are reached, preventing driver fatigue, drowsiness, and exhaust gas suicides. CO concentrations of 30 ppm and oxygen levels lower than 19.5% were experienced whilst driving

Optimum sensitive area of surface acoustic wave resonator chemical and bio-sensors

A model is developed to map the variation of sensitivity of a surface acoustic wave (SAW) resonator sensor over its surface, in order to find the region with maximum sensitivity. The model is based on a combined coupling of modes (COM) and periodic Green's function analysis. In order to extend the analysis to layered media, a new efficient technique is introduced to account for the mechanical interactions with buried electrodes. Using this technique the sensitivity calculations are found to be in good agreement with measurements. It is also shown that whilst changes in other parameters influence the sensitivity, it is the velocity change which most strongly determines the overall frequency change

Spatial sensitivity distribution of surface acoustic wave resonator sensors

The sensitivity distribution of surface acoustic wave (SAW) resonator sensors is investigated by theoretical and experimental means. It is shown that the sensitivity to mass loading varies strongly across the surface due to the confinement of acoustic energy toward the center of the device. A model is developed for this phenomenon based on the extraction of coupling of modes parameters from a rigorous boundary element method analysis based on a periodic Green's function. As SAW sensors for many applications include a layer covering the electrodes, a new technique is introduced to account for the mechanical interactions with buried electrodes. Using this technique, the sensitivity calculations are found to be in good agreement with measurements. It is also shown that while changes in other parameters influence sensitivity, it is velocity change that most strongly determines overall frequency change

UV-induced wettability change of teflon-modified ZnO nanorod arrays on LiNbO3 substrate

Aligned ZnO nanorod arrays films were grown on LiNbO3 substrates by aqueous growth, and subsequently rendered superhydrophobic with RF sputtered coated Teflon. The as-prepared surface exhibits superhydrophobicity with a water contact angle (CA) of 154.5deg. After 2 hours of UV irradiation on the surface, the surface wettability was approaching hydrophilic state; CA was measured to be 113deg. This study provides insights into the methodology of a low cost, efficient technique that has great potential for preparing nanostructured surface with tunable wettability