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Development of Pd/TiO2 Porous Layers by Pulsed Laser Deposition for Surface Acoustic Wave H2 Gas Sensor
摘要： The influence of sensitive porous films obtained by pulsed laser deposition (PLD) on the response of surface acoustic wave (SAW) sensors on hydrogen at room temperature (RT) was studied. Monolayer films of TiO2 and bilayer films of Pd/TiO2 were deposited on the quartz substrates of SAW sensors. By varying the oxygen and argon pressure in the PLD deposition chamber, different morphologies of the sensitive films were obtained, which were analyzed based on scanning electron microscopy (SEM) images. SAW sensors were realized with different porosity degrees, and these were tested at different hydrogen concentrations. It has been confirmed that the high porosity of the film and the bilayer structure leads to a higher frequency shift and allow the possibility to make tests at lower concentrations. Thus, the best sensor, Pd-1500/TiO2-600, with the deposition pressure of 600 mTorr for TiO2 and 1500 mTorr for Pd, had a frequency shift of 1.8 kHz at 2% hydrogen concentration, a sensitivity of 0.10 Hz/ppm and a limit of detection (LOD) of 1210 ppm. SAW sensors based on such porous films allow the detection of hydrogen but also of other gases at RT, and by PLD method such sensitive porous and nanostructured films can be easily developed.
关键词： bilayer films,pulsed laser deposition (PLD),palladium,hydrogen sensor,surface acoustic wave (SAW),Pd/TiO2,porous morphology,titanium dioxide
更新于2025-09-23 15:19:57
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[IEEE 2018 International Conference on Emerging Trends and Innovations In Engineering And Technological Research (ICETIETR) - Ernakulam, Cochin, India (2018.7.11-2018.7.13)] 2018 International Conference on Emerging Trends and Innovations In Engineering And Technological Research (ICETIETR) - Analysis of VOC Using Sensor Array for Early Detection of Breast Cancer
摘要： Breast Cancer is the most common cause of cancer-related deaths among women worldwide. Early detection of the breast cancer can increase the survival rate. Studies show that women whose breast cancer is detected at an early stage have 93% or higher rate of survival in the first 5 years. The available diagnostic methods have limited accuracy in various scenarios. A good screening method is always supported by a report of reduced death rate after the implementation. In the present scenario, Mammography can be considered as best among the screening methods available. But the accuracy of the test is low in the case of women below the age of 50 as their breast has high mammary gland density. Recent research in the region of that Volatile Organic Compounds (VOCs) in the human breath can be used as potential cancer diagnosing tool. This study makes use of the presence of these VOCs to create a non-invasive diagnostic tool with reduced mortality rate upon implementation [1][4][9].
关键词： Breast Cancer,VOCs,Breath Analysis,SAW Sensor
更新于2025-09-23 15:19:57
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[IEEE 2018 IEEE SENSORS - New Delhi, India (2018.10.28-2018.10.31)] 2018 IEEE SENSORS - Finite Element Modelling and Computational Analysis of Mechanical Properties of Carbon Composite-Based Love Wave Sensor
摘要： Structured materials are of interest to emphasize the sensitivity of gas or bio-sensors. This work focuses on carbon-polymer composite (PEDOT:PSS-MWCNT) and additional multiwalled carbon nanotubes (MWCNT), deposited by inkjet printing on Love acoustic wave devices. This combination is studied, both with simulation based on finite element modelling and computational analysis of a reduced model, and experimental measurements. This allows for an estimation of the Young modulus of each material: 70 GPa and 150 GPa for the PEDOT:PSS-MWCNT bilayer composite material (? 450nm) and for the MWCNT bilayer on carbon composite (?140nm), respectively. The value is lower than that obtained in the literature, which has been attributed to the material porosity. An enhanced waveguiding effect is observed, which is interesting for further detection applications.
关键词： MWCNT,PEDOT:PSS,Gas sensor,FEM,SAW,Bio sensor
更新于2025-09-19 17:15:36
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[IEEE 2018 IEEE International Ultrasonics Symposium (IUS) - Kobe, Japan (2018.10.22-2018.10.25)] 2018 IEEE International Ultrasonics Symposium (IUS) - Analysis of SAW Scattering at Discontinuity Between Periodic Gratings Using Travelling Wave Excitation and Hierarchical Cascading Technique
摘要： This paper proposes a technique to analysis SAW scattering at discontinuity in grating structures using the hierarchical cascading technique. The traveling wave excitation is applied to generate a specific SAW mode. Then the displacement distribution is obtained for the passive regions. The incident, reflected and transmitted components are selectively evaluated by the Fourier transform so as to determine the scattering coefficients at the discontinuity. Rayleigh SAWs on the SiO2/128oYX-LiNbO3 structure are used as an example, and the behavior of discontinuity is analyzed, and obtained results are compared with those obtained by the COM model. These results agreed very well for this case.
关键词： SAW scattering,traveling wave source,hierarchical cascading
更新于2025-09-19 17:15:36
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Hydrogen Detection with SAW Polymer/Quantum Dots Sensitive Films
摘要： Regarding the use of hydrogen as a fuel, it is necessary to measure its concentration in air at room temperature. In this paper, sensitive composite films have been developed for surface acoustic wave (SAW) sensors, using quantum dots (QDs) and polymers. Si/SiO2 QDs were used due to having a high specific surface area, which considerably improves the sensitivity of the sensors compared to those that only have a polymer. Si/SiO2 QDs were obtained by laser ablation and analyzed by X-ray diffraction and transmission electron microscopy (TEM). Two types of polymers were used: polydimethylsiloxane (PDMS) and polymethylmethacrylate (PMMA). Polymer and polymer with QDs compositions were deposited on the sensor substrate by drop casting. A heat treatment was performed on the films at 80°C with a thermal dwell of two hours. The sensors obtained were tested at different hydrogen concentrations at room temperature. A limit of detection (LOD) of 452 ppm was obtained by the sensor with PDMS and Si/SiO2 QDs, which was heat treated. The results demonstrated the potential of using QDs to improve the sensitivity of the SAW sensors and to achieve a heat treatment that increases its adsorption capacity of the gas molecules.
关键词： quantum dots,gas detection,gas sensor,hydrogen sensor,surface acoustic wave,polymer,composite,SAW sensor
更新于2025-09-19 17:13:59
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Laser Ablation - From Fundamentals to Applications || Matrix-Assisted Pulsed Laser Evaporation of Organic Thin Films: Applications in Biology and Chemical Sensors
摘要： Polymer and biomolecule processing for medical and electronics applications, i.e. the fabrication of sensors and biosensors, microarrays, or lab on chip devices is a cornerstone field which shows great promise. Laser based thin film deposition techniques such as pulsed laser deposition or matrix-assisted pulsed laser evaporation (MAPLE) are competing with conventional methods for integrating new materials with tailored properties for novel technological developments. Successful polymer and protein thin film deposition requires several key elements for depositing viable and functional thin films, i.e. the characteristics of the laser depositing system, the choice of targets and receiver substrates, etc. This chapter reviews the following topics: brief presentation of the MAPLE process including several examples of polymer materials deposited by MAPLE, thus illustrating the potential of the technique as a gentle laser-assisted deposition method. In particular, the “synthesis” of new materials, their analysis and correlation of the bulk and interface properties to its bio-environment shall be discussed as a method to tackle some bioengineering issues. We will also focus on recent breakthroughs of the MAPLE technique for the fabrication of functional devices, i.e. sensor devices based either on chemoresponsive polymers or on proteins.
关键词： saw,maple,hydroxyapatite nanoparticles,odorant-binding proteins,PEG-PCL-me,polyethylenimine,polyepichlorohydrin,ha,polyethylene glycol-co-polycaprolactone methyl ether,polyisobutylene,lactoferrin
更新于2025-09-19 17:13:59
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[IEEE 2019 4th International Symposium on Instrumentation Systems, Circuits and Transducers (INSCIT) - Sao Paulo, Brazil (2019.8.26-2019.8.30)] 2019 4th International Symposium on Instrumentation Systems, Circuits and Transducers (INSCIT) - Normalized Spectral Responsivity Measurement of Photodiode by Direct Method Using a Supercontinuum Laser Source
摘要： A Taguchi-based-genetic algorithm (TBGA) is used in an adaptive neuro-fuzzy inference system (ANFIS) to optimize design parameters for surface acoustic wave (SAW) gas sensors. The Taguchi method is used to reduce the number of experiments and collect performance data for an SAW gas sensor. The TBGA has two optimization roles. In the ANFIS, the TBGA selects appropriate membership functions and optimizes both the premise and the consequent parameters by minimizing the performance criterion of the root mean squared error. Another role of the TBGA is optimizing design parameters for an SAW gas sensor. Simulated experimental application of the proposed TBGA-based ANFIS approach showed that, in terms of both resonant frequency shift and precision performance, this systematic design approach obtains far superior results compared with the conventional trial-and-error design methods and other Taguchi-based design methods.
关键词： Adaptive network fuzzy inference system,Taguchi-genetic algorithm,surface acoustic wave (SAW) gas sensors
更新于2025-09-19 17:13:59
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Love Wave Surface Acoustic Wave Sensor with Laser-Deposited Nanoporous Gold Sensitive Layer
摘要： Laser-deposited gold immobilization layers with different porosities were incorporated into Love Wave Surface Acoustic Wave sensors (LW-SAWs). Acetylcholinesterase (AChE) enzyme was immobilized onto three gold interfaces with different morphologies, and the sensor response to chloroform was measured. The response of the sensors to various chloroform concentrations indicates that their sensing properties (sensitivity, limit of detection) are considerably improved when the gold layers are porous, in comparison to a conventional dense gold layer. The results obtained can be used to improve properties of SAW-based biosensors by controlling the nanostructure of the gold immobilization layer, in combination with other enzymes and proteins, since the design of the present sensor is the same as that for a Love Wave biosensor.
关键词： pulsed laser deposition,Au,gas sensor,Love Wave,nanoporous film,SAW sensor
更新于2025-09-19 17:13:59
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[IEEE 2019 Photonics & Electromagnetics Research Symposium - Fall (PIERS - Fall) - Xiamen, China (2019.12.17-2019.12.20)] 2019 Photonics & Electromagnetics Research Symposium - Fall (PIERS - Fall) - A Wideband Fabry-Perot Antenna with Low-RCS High-GBP Using Embed-chessboard Polarization Conversion Metasurface
摘要： An improved adaptive neuro-fuzzy inference system (IANFIS) is proposed to build a model to predict the resonant frequency shift performance of surface acoustic wave (SAW) gas sensors. In the proposed IANFIS, by directly minimizing the root-mean-squared-error performance criterion, Taguchi-genetic learning algorithm is used in the ANFIS to find both the optimal premise and consequent parameters and to simultaneously determine the most suitable membership functions. The five design parameters of SAW gas sensors are considered to be the input variables of the IANFIS model. The input variables include the number of electrode finger pairs, the electrode overlap, the separation distance of two interdigital transducers on the substrate, the dimensions of the stable temperature-cut (ST-cut) quartz substrate, and the electrode thickness. The output variable of the IANFIS model is composed of the resonant frequency shift performance. The results predicted by the proposed IANFIS are compared with those obtained by the back-propagation neural network. The comparison has shown that the performance prediction of resonant frequency shift using the proposed IANFIS is effective. In addition, the sensitivity analyses of the five design parameters have also shown that both the electrode overlap and the dimensions of the ST-cut quartz substrate have the most influence on the resonant frequency shift performance.
关键词： Adaptive neuro-fuzzy inference system,surface acoustic wave (SAW) gas sensors,Taguchi-genetic learning algorithm
更新于2025-09-19 17:13:59
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[IEEE 2018 3rd International Symposium on Instrumentation Systems, Circuits and Transducers (INSCIT) - Bento Gon?alves, Brazil (2018.8.27-2018.8.31)] 2018 3rd International Symposium on Instrumentation Systems, Circuits and Transducers (INSCIT) - Finite Element Modelling design and optimization of Love Wave mesoporous transducers for biochemical detection in liquid medium
摘要： We study numerically by a Finite Element Modeling (FEM) approach the design and the optimization of a Love wave transducer coated with a mesoporous sensitive layer. This association could allow to realize an easy functionalizable transducer for biochemical detection in liquid medium. The FEM approach is a good way to design the transducer by estimating many physical parameters in order to obtain a device which could work properly for a given application. Especially, by using a porous layer coated on an acoustic Love wave transducer, we need to be sure that the propagation parameters are still compatible with a usable device. In this paper, after a description of the reduced finite element model of the Love wave transducer, we show that the first experimental results are in a good agreement with the simulations. An “ultra-reduced” FEM approach of the Love wave transducer is carried out for easier consideration of the porous sensitive coating. Finally, experimental transducers are coated with TiO2 porous sensitive layers by the sol gel technique: the porosity is varied in the range from 10% to 25 %, the pore size from 10 nm to 200 nm, and the thickness from 100 nm to 500 nm. Simulated and experimental results are in good accordance, and allow us to conclude that such transducer could achieve a good propagation of the acoustic wave for biochemical sensing.
关键词： liquid medium,biochemical detection,SAW transducers,mesoporous layer,FEM simulation
更新于2025-09-11 14:15:04