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SAW Delay Line Modelling of SAW delay line is carried out using three different types of models namely, Impulse Response Model, Crossed-field Equivalent Circuit Model (ECM) and Coupling of Modes (COM) model, each having its own limitations. This paper describes and compares the results obtained from selected models.
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This paper describes a comparative modelling study of Surface Acoustic Wave (SAW) devices. The Surface Acoustic Waves (SAWs) are generated and received by the interdigital transducer (IDT) on a piezoelectric substrate. SAW device design parameters like piezoelectric substrate, structure of IDT, number of finger pairs, device frequency and etc., are...
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The most vital step in the development of novel and existing surface acoustic wave (SAW)-based sensors and transducers is their design and optimization. Demand for SAW devices has been steadily increasing due to their low cost, portability, and versatility in electronics, telecommunications, and biosensor applications. However, a full characterizat...
Surface Acoustic Wave (SAW) devices like delay lines, filters, resonators etc., are nowadays extensively used as principal solid state components in many electronic applications and chemical vapour sensors. To bring out the best from these SAW devices, computational design and modelling are resorted too. The present paper proposes the modelling of...
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... Consequently, terrorists can employ TICs as a preferred weapon (Arshak et al. 2004;Gongora et al. 2018;Bongiovanni Abel et al. 2018;Benetti et al. 2019;Wang et al. 2019;P.Gowdhaman et al. 2020). The hazard index rank (ITF-25) categorizes TICs as high, medium, or low hazard based on the chemical's manufacture, conveyance, stockpiling, poisonous, and vapor pressure (Wohltjen et al. 1979;Chang et al. 1998;Cheeke et al. 1999;Islam et al. 2015;Bui et al. 2016;Priya et al. 2016;Devkota et al. 2017). VOCs that are not immediately dangerous but have long-term effects interfere with the detection of CW agents very often. ...
... The different chemicals reach the GC outlet at different time intervals because they travel at different speeds within the GC column. Separated sample vapors are allowed into SAW e-Nose sensor for further detection and identification (Bui et al. 2016;Priya et al. 2016;Singh et al. 2016;Devkota et al. 2017). ...
The characterization of a custom-designed GC-based SAW e-Nose sensor system is presented here to study the sensing ability of the sensor system to detect and identify low medium and high toxic vapors. A semi-automated multi-vapor generator generates vapors of chemical compounds that are then exposed to the sensing system to examine its performance under various concentrations. Time-domain verses frequency response of GC-SAW Sensor is noted for repeated cycles against different chemical compounds like xylene, 1,2 dibromoethane, dimethyl sulfate, triethyl phosphate, nitrobenzene, phosphorous trichloride being tested. The generated data is examined using a principle component analysis (PCA) technique to detect a unique response for an individual chemical compound. Experimental results are reported.
... Surface acoustic waves (SAW) based technology provides a noticeable delay at lower microwave frequencies [4]. However, the excitation and reception of the surface acoustic waves limit the behavior of this approach. ...
... A detailed study of diverse polymer and metal oxide sensing layer and the applicability of these for detection of biological and chemical threats have been reported by Gowdhaman et al. 2018(Gowdhaman et al. 2018.Any change in the mass, mechanical, orelectric properties of this layer upon exposure to the foreign molecules disturbs the surface wavesenabling the devices to use as sensors. A study on design, modelling, development and operation of a SAW sensor and its application to e-Nose devices had been reported in some of our research article published elsewhere (Haresh, 2010;Venkatesan and Pandya, 2013;Haresh et al. 2013;Banu Priya et al. 2014;Sharma et al. 2014;Priya et al. 2016). ...
Sensor technology is a rapidly developing field and the ubiquitous nature of a sensor in present-day today's life is evidently observed by one and all. Even so, fabricating a chemical sensor that can detect and distinguish multiple gas vapors in a harsh environment is a big challenge. Many commercially available gas sensors have various inbuilt disadvantages and can rarely be used whenever the detection of multiple toxins in the air is absolutely necessary. The solution to this problem, therefore, lies in integrating experimental sensing by devices to library pattern recognition systems. The subsequent sensor is called an electronic nose or e-Nose and it displays an array of sensors with different sensitive coatings for sensing multiple analytes. The present research paper focuses on a comprehensive review of the design and development of the latest e-Nose sensor technologies from 1994 onwards with special reference to detection and identification of the minimal amount of toxic agents / chemical warfare agents in a complex dynamic environment with their advantages and disadvantages.
... The impedance-loaded sensors are mainly analysed using delta function model, the equivalent circuit model and coupling-of-mode (COM) model [4][5][6][7]. However, the delta function model ignores the influence of electrode pairs on the performance of sensors and the equivalent circuit model is complicated to be deduced. ...
Instead of a conventional wireless transceiver system that requires batteries and complex circuits, the surface acoustic wave (SAW) sensor enables wireless passive measurement. A sensor consisting of an SAW device and external impedance sensing element is analysed. Since the reflection coefficient of the reflective grating on the SAW device depends on the load impedance, the echo characteristics are influenced by the change in the impedance of external sensing element. A resistance sensor or a capacitive sensor is selected as the external sensing element. The two different types of sensors are simulated using coupling-of-mode (COM) modelling, and the relationships between amplitude and phase with load impedance are analysed. On the basis of COM theory, a wireless impedance-loaded SAW sensor is fabricated by the lift-off process and tested by a network analyser to verify the simulation results. It is observed that the test results agree well with the simulation results. The phase change is more sensitive than the amplitude based on the results obtained. The sensitivity is 0.274°/Ω for the sensor with resistance and the sensitivity of the sensor with capacitance is 1.096°/pF. These results can guide the design of the high sensitivity impedance-loaded SAW sensors in the future. © 2019 Institution of Engineering and Technology. All rights reserved.
... At the input IDT, the applied electric field produces me- chanical waves (due to the inverse piezoelectric effect) which are transmitted towards the output IDT and converted back to electrical field (due to piezoelectric effect). The delay (τ ) produced by the SAW sensor depends on the distance between the centres of input and output IDTs (L) and the SAW velocity for a par-ticular substrate (v 0 ) which is expressed as τ = L/v 0 (Venkatesan, Pandya, 2013;Pandya et al., 2013;Banupriya et al., 2014;Priya et al., 2016). ...
... The SAW delay line and resonators are promising devices for chemical sensing applications due to the ease of fabrication, relatively large sensitive area and reliability over other devices. The absorbers made of thin silicon film are placed on both the ends of the substrate to ensure the unidirectional flow of acoustic waves which helps to overcome the loss due to interfer- ence (Pandya, 2010;Afzal et al., 2013;Priya et al., 2016). ...
... The performance of a SAW sensor primarily de- pends on the operating frequency and sensitive layer in the active region of the sensor. Therefore, parame- ters such as number of IDT finger pairs, finger width, acoustic aperture, transducer periodicity, electrome- chanical coupling coefficient, substrate velocity, oper- ating frequency, and IDT geometry have to be taken into consideration before the fabrication of a SAW sensor (Afzal et al., 2013;Banupriya et al., 2014;Sharma et al., 2014;Priya et al., 2016). The pre- fabrication modelling and simulation of SAW sensors using standard models is helpful to optimize these parameters for real time analysis. ...
Detection and identification of toxic environmental gases have assumed paramount importance precisely in the defense, industrial and civilian security sector. Numerous methods have been developed for the sensing of toxic gases in the environment ever since surface acoustic wave (SAW) technology came into existence. Such SAW sensors called electronic nose (E-Nose) sensor use the frequency response of a delay line/resonator. SAW device is focused and given importance. The selective coating between input and output interdigital transducers (IDTs) in the SAW device is responsible for corresponding changes in operating frequency of the device for a specific gas/vapour absorbed from the environment. A suitable combination of well-designed SAW delay lines with selective coatings not only help to improve sensor sensitivity and selectivity but also leads to the minimization of false frequency alarms in the E-Nose sensor. This article presents a comprehensive review of design, development, simulation and modelling of a SAW sensor for potential sensing of toxic environmental gases.
... The SAW sensor is a miniature sensor developed based on the principle of acoustic-electrical transduction. Given the characteristics of small volume, low power consumption and high tolerance, it is suitable for the complex environment under coal mine (M'Jahed et al. 2011;Priya et al. 2016). At present, miniature and inexpensive SAW devices are available on the market, but these SAW devices are not suitable for fabricating gas sensors because of such problems as too small coated area and low interdigital processing accuracy (Priya et al. 2015). ...
Since the current mining catalytic combustion-type methane sensor is not a detection device used at normal temperature, it is found to have such problems under high temperature conditions (> 450 °C) as poor thermal stability, frequent calibration, short service life and high power consumption. To this end, this paper has studied a room temperature working device that uses cryptophane-E as gas sensitive material, that is, SAW methane sensor. The “three-step approach” is adopted to prepare cryptophane-E material and characterize HUMR and SEM. COMSOL software is used to simulate the rationality of the parameter design of the delay linetype SAW methane sensor. Electron beam exposure photoresist method is used to prepare interdigital electrode on the quartz substrate and form the delay linetype SAW devices, and sensitive materials are loaded using the dispensing method. A sensor performance test system is set up to measure the sensor’s response characteristics at the concentration of 0–5%CH4 using nitrogen as carrier gas. The study shows that the sensor has good response recovery performance within the test concentration range, and the frequency offset is positively correlated with methane concentration; the sensor’s 90% response time is 50 s, 90% recovery time is 72 s, and the sensor sensitivity is 118.8 Hz ± 5 Hz/(1%CH4). The study provides a reference for the development of a new SAW methane sensor, but the temperature and humidity effects and gas selectivity have yet to be further studied.
... Fig. 1, shows the relation between the time domain response obtained at different finger/electrode locations (Peroulis et al. 2016). An alternatively, the device response is looking in terms of its frequency response in the frequency-domain, which is obtained mathematically from the time-domain impulse response by performing a Fourier transform (Harris, 1978), (Priya et al. 2016). Since, the low signals can be resolved in the frequency-domain. ...
In the present paper, a 70 MHz LiNbO3 SAW filter device is designed, modelled and simulated. The frequency sampling methods and the windowing methods are adopted, and using user defined MATLAB® simulation tool was employed for developing the algorithms. A computationally simulated frequency response of 70 MHz SAW filters has compared with experimental device result. These device responses utilized and implemented during the design and development stage of these devices for their potential applications in mobile communication systems (GSM/CDMA/WCDMA) for filtering the higher order as well as intermediate frequencies.
... SAW delay line as sensor is used for the detection and identification of various types of target gases that has been realized by making use of very basic property of SAW device (Banupriya et. al. 2015;2016) fig. 1. SAW delay line shown in Figure 1 consisting of two simple IDT structures. One IDT acts as the input or the transmitting IDT, to create SAW which then propagates through the length of the piezoelectric substrate towards the output or the receiving IDT's. ...
Currently, Surface Acoustic Wave(SAW) devices find themselves in many common commercial applications like consumer electronics and telecommunications, where their ability to generate, condition and process radiofrequency (RF) signals is employed to manufacture on a large scale, devices like delay lines, bandpass filters, resonators, convolvers, radar pulse compression. filters, sensors, etc. This paper reports on the comparison of three methods of modelling SAW's. The three models are Impulse Response Model (IRM), Crossed-field Equivalent Circuit Model (ECM) and Coupling of Modes Model (COM). The results were used to calculate the insertion loss and bandwidth of SAW delay line using 50 finger pairs operating at a centre frequency of 200MHz. The modelling study was carried out using MATLAB® as a simulation tool. The results show that the SAW designs based on three models are adequate for sensor applications.
Surface Acoustic Wave (SAW) devices like delay lines, filters, resonators etc., are nowadays extensively used as principal solid state components in many electronic applications and chemical vapour sensors. To bring out the best from these SAW devices, computational design and modelling are resorted too. The present paper proposes the modelling of 400 MHz ST-X Quartz based SAW delay line, by three models namely, Impulse Response Model (IRM), Crossed-field Equivalent Circuit Model (ECM) and Coupling-of-Modes (COM) model. MATLAB is employed as a computational tool to model the experimental output of the SAW device. A comparative discussion of the modelled device results is also provided.
