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

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

Study of novel Love mode surface acoustic wave filters

Novel Love mode filters based on ZnO and SiO<sub>2</sub>/90° rotated ST-cut quartz crystal structure were fabricated. A comprehensive study was carried out to show the capabilities of such filters. The periodicity of the fingers is 50 μm and the thickness of the SiO<sub>2</sub> and ZnO layers ranges from 0.2 to 7.2 μm. Electromechanical coupling coefficient, capacitance per unit wavelengths of finger pairs and temperature coefficient of frequency are studied in terms of thickness of the wave-guiding layers

Love mode SAW sensors with ZnO layer operating in gas and liquid media

Novel layered surface acoustic wave (SAW) sensors, based on a ZnO/90° rotated ST-cut quartz crystal structure, were fabricated. They were employed for liquid and gas sensing applications. Their mass detection limit in liquid media is as low as 100 pg/cm2. Furthermore, these sensors are able to sense oxygen gas concentrations as low as 0.2 ppm in nitrogen gas

A room temperature polyaniline nanofibre hydrogen gas sensor

Electro-conductive polyaniline (PANI) nanofiber based surface acoustic wave (SAW) gas sensors have been investigated with hydrogen (H 2) gas. A template-free, rapidly mixed method was employed to synthesize polyaniline nanofibers using chemical oxidative polymerization of aniline. The nanofibers were deposited onto a layered ZnO/64° YX LiNbO3 SAW transducer for gas sensing applications. The novel sensor was exposed to various concentrations of H2 gas at room temperature. The sensor response, defined as the relative variation in operating frequency of oscillation due to the introduction of the gas, was 3.04 kHz towards a 1% H2 concentration. A relatively fast response time of 8 sec and a recovery time of 60 sec with good repeatability were observed at room temperature. Due to room temperature operation, the novel gas sensor is promising for environmental and industrial applications

A room temperature polyaniline nanofiber hydrogen gas sensor

Abstract—Electro-conductive polyaniline (PANI) nanofiber based Surface Acoustic Wave (SAW) gas sensors have been investigated with hydrogen (H2) gas. A template-free, rapidly mixed method was employed to synthesize polyaniline nanofibers using chemical oxidative polymerization of aniline. The nanofibers were deposited onto a layered ZnO/64º YX LiNbO3 SAW transducer for gas sensing applications. The novel sensor was exposed to various concentrations of H2 gas at room temperature. The sensor response, defined as the relative variation in operating frequency of oscillation due to the introduction of the gas, was 3.04 kHz towards a 1 % H2 concentration. A relatively fast response time of 8 sec and a recovery time of 60 sec with good repeatability were observed at room temperature. Due to room temperature operation, the novel gas sensor is promising for environmental and industrial applications. I

Car cabin air quality sensors and systems

No abstract availabl

A study of CO sensors with oscillatory response

In this paper, oscillatory changes in the conductance of catalyst-doped SnO2 semiconductor materials in the presence of CO gas are investigated. The sensors with various transducing structures of ceramic tubes (Taguchi structure), co-axial Pt coils and substrates with deposited interdigital electrodes are compared. The results show that catalysts in the sensing materials and the sensor's operating temperature play a key role in generating an oscillatory response. A unique oscillatory response is observed when a bare Pt coil is exposed to CO gas. The relationship between the oscillation waveforms, gas concentration, operating conditions and gas flow rates for the Pt coils are preliminarily tested and discussed

A Pt/Ga2O3/SiC Schottky diode based hydrocarbon gas sensor

This paper presents the propene gas sensing performance of Pt/Ga<sub>2</sub>O<sub>3</sub>/SiC based Schottky diodes. The metal oxide semiconducting Ga<sub>2</sub>O<sub>3</sub> thin films were doped with Zn and prepared by the sol-gel process. The thin films were deposited onto the SiC by the spin coating technique and a Pt layer was deposited on the top of the metal oxide forming the Schottky diode. The sensor responses were stable and repeatable towards propene at operating temperatures between 300 and 600°C. The diodes were biased at a constant current of 2 mA. When exposed to 1,900 ppm of propene at an operating temperature of 525°C, a shift of 85 mV was observed