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This paper presented a surface acoustic wave (SAW) based particulate matter (PM) 2.5 monitor, which consisted of a SAW dual-resonator oscillator, a thermophoresis unit and a virtual impactor. The structure optimization for improving the performance of the sensor by considering the particle distribution deposited by thermophoresis on the SAW detector was analyzed and verified in experiments. The size...
Lung cancer is the leading cause of cancer death in China and the whole world. Early diagnosis is key to reduce the mortality from lung cancer. Exhaled breath analysis can be used in the early screening of lung cancer. Many scientists in the world have carried out the research and nominated dozens of volatile organic compounds as biomarkers for lung cancer. But the results from different researchers...
This paper has studied the influence of filling fraction on the band gaps of two-dimensional (2-D) piezoelectric phononic crystals (PnCs) in radio frequency (RF). The 2-D piezoelectric PnCs consists of tungsten (W) stubs on the finite slab of 128°YXLiNbO3 substrate. With Bloch periodic theorem, the single cell model was built using the three-dimensional (3-D) finite element method (FEM). Based on...
Accurately measurement and monitor on methane gas (CH4) concentration is an urgent problem to be solved in the purpose of safety and process control in homes, industries and mines. This paper proposed a new surface acoustic wave (SAW) based methane gas sensor, which was coated by a supra-molecular cryptophane A (CrypA). A differential SAW oscillator with excellent frequency stability was performed,...
Carbon black combined PDMS is a promising material for laser ultrasonic inspection but the generated ultrasound field characteristics have not been studied. To obtain the wave field generated by laser in the polymer material, thermo-elasticity model was adopted, a 2D axial symmetry finite element model is built and the physics and parameters are set as actual situation for ultrasonic wave generation...
Temperature characteristics of SU-8 photoresist coated love wave devices are presented from 0 °C to 120 °C. Surface skimming bulk wave (SSBW) and love wave delay line devices were fabricated on the ST-90°X quartz substrate. Effects of SU-8 thickness on insertion loss and temperature range of near-zero temperature coefficient of frequency (TCF) are investigated. Love wave devices with −15.5dB to −22...
This paper presents a novel approach for PM2.5 monitoring by using the Surface Acoustic Wave (SAW) based sensor. To analyze the response mechanism of SAW sensor, the mass loading effect from the PM2.5 layer to SAW propagation was described by solving the coupled electromechanical field equation in layered structure and surface effective permittivity (SEP). The dispersion curve of the SAW propagation...
In this paper, an experimental investigation was performed on humidity sensing by using Love wave devices coated with different polymeric layers. The Love wave device consists of two interdigital transducers (IDTs) with a period of 28 μm, an ST-90˚X quartz substrate. Three different films of SU-8, SU-8+PVA and PVA, were spin-coated on the substrate surface by a sol-gel process as the waveguide layer...
As a new structure, reflecting gratings based on two-dimensional (2-D) piezoelectric phononic crystals (PCs) have been studied for several years. This paper has proposed an approach to analyze the reflectivity of this reflecting grating in two directions. In the method, resonant modal was firstly analyzed with three-dimensional (3-D) finite element method (FEM) using the commercial software COMSOL...
A three-dimensional (3D) finite element method (FEM) model was proposed to analyze the resonant modal of the transducers based on two-dimensional (2D) phononic crystals (PnCs). Using this model two modals existed with symmetric modal and anti-symmetric modal can be extracted, and then reflectivity of the transducers was derived. An example of transducer based on 2D PnCs composed of IDTs of aluminum...
This paper has proposed a weighted waveguide for surface acoustic waves (SAW) based on two-dimensional piezoelectric phononic crystals (PnCs). In order to analyze the transmission of the weighted waveguide based on PnCs, SAW delay line model was built. In the model, period boundary condition was adopted to reduce the time and memory of model cost and perfect matching layer was adopted to absorb the...
The impacts of two immobilization methods, which are Biotin-avidin system (BAS) and Self-assembled monolayer technology (SAM), made on the performance of aptasensors in terms of acoustics were analyzed through experiment. Love-wave aptasensors were designed by coupling aptamers to the surface of a Love-wave sensor with the two methods respectively. Abrin is chosen as the analyte. For certain concentrations...
This paper aimed to study the pressure sensitive coefficients of different cuts of quartz for the surface acoustic wave(SAW) pressure sensors with non-uniform pressure load, and tried to find the most sensitive cut. The finite element analysis/ perturbation theory combines model was constructed to calculate the pressure sensitive coefficients. For analysis of different cut angles (0, θ, φ) of quartz...
Phononic crystals (PCs) have promising band gaps, in which Surface Acoustic Wave (SAW) propagating is prohibited. Several numerical methods have already been developed and applied to analyze piezoelectric PCs, most of them have various disadvantages, as they cannot calculate the transmission characteristic of the limited structure or cannot provide the propagation process for SAW in time domain. The...
A surface acoustic wave (SAW)-based sensor coated with SnO2 thin layer is investigated for H2S sensing. The conventional semiconductor sensor usually works in higher temperature (>;150°C) by resistance effect and performs with low sensitivity (>;10ppm). Compared with conventional semiconductor sensor, the SAW-based sensor is affected not only by conductivity but also by mass loading. Both of...
A love-wave biosensor has been designed by coupling aptamers to the Au-surface of sensor chip. Aptamers are artificial nucleic acid ligands that can be obtained in the process of SELEX. Aptamers have advantages over antibodies, such as high affinity, specificity, and stability. As Love waves' acoustic energy is confined to a thin near-surface region of substrate by guiding layer, Love wave sensors...
The paper introduces a rigorous numerical model to analyze SAW (surface acoustic wave) resonators by BEM (boundary element method). At first it is proposed that the mass-loading effect of electrode is neglected and the surface of substrate is free, and the substrate is semi-infinite. Then corresponding programs are developed to analyze a SAW resonator. Electrical charge distribution on the electrode-substrate...
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