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Nanomechanical Microfluidic Mixing and Rapid Labelling of Silica Nanoparticles with Allenamide to Thiol Covalent Link for Bioimaging
摘要： Rapid surface functionalization of nanomaterials using covalent linkage following ‘green chemistry’ remains challenging and the quest for developing simple protocols are persisting. We report a nanomechanical microfluidic approach for the coupling of allenamide functionalized organic derivatives on the surface of thiol modified silica nanoparticles using allenamide-thiol chemistry. The coupling principle involves the use of a microfluidic surface acoustic wave (SAW) device that generates acoustic streaming based chaotic fluid micromixing that enables mixing of laterally flowing fluids containing active components. This approach was used to demonstrate the direct surface labeling of thiol modified silica nanoparticles using a selected group of modified fluorescence tags containing allenamide handles and achieved a total efficiency of 83-90 %. This green approach enabled a highly efficient surface functionalization in aqueous conditions, with tunable control over the conjugation process via the applied field. The dye labelled silica particles were characterized using various analytical techniques and found to be biocompatible with a potential in live cell bioimaging. It is envisaged that this bioconjugation strategy will find numerous applications in the field of bioimaging and drug delivery.
关键词： microfluidics,surface acoustic wave (SAW),allenamide-thiol chemistry,bioimaging,nanoparticles
更新于2025-09-23 15:23:52
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Behavior of Al/Cu/Ti electrodes in surface acoustic wave filter at high power
摘要： Driven by the need for high data-rates and continuous reduction in device size, surface acoustic wave filters are required to work under increasingly high power. In this work, a series of 2.7 GHz surface acoustic wave filters with Al/Cu/Ti three-layered electrode were fabricated and loaded with high power. Those three-layered electrodes showed weaker texture but higher stability than Al-Cu alloy electrode at high power. Morphologies, microstructures and elements distribution in cross section of fingers were analyzed carefully before and after high power loading. Results show that the circular-arc-shaped outline of fingers were appeared in most samples after high power loading, and the number of gains in the finger cross section changed from some into several with much larger volume. The features of distribution of Cu atoms also coincided with these microstructures. By finite element method and phase diagram analysis, the higher stability of Al/Cu/Ti three-layered electrodes are attributed to precipitation of θ-CuAl2 in the bottom edge of electrode finger and Cu-doped α-Al in the center top.
关键词： stress,Al-Cu alloy,high power,surface acoustic wave filter,three-layered electrode
更新于2025-09-23 15:23:52
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Surface Acoustic Wave Gyroscopic Effect in an Interdigital Transducer
摘要： The surface acoustic wave (SAW) gyroscopic effect in an interdigital transducer (IDT) deposited on a piezoelectric substrate is different from that in the piezoelectric substrate due to a reflection induced by IDT. In this work, an extended coupling-of-mode (COM) model including the gyroscopic effect and the reflection was developed to analyze the SAW gyroscopic effect. First, dispersion characteristics parameters of SAW were fitted according to the data derived using the finite element method (FEM). Then, variations of stop band edge frequency were calculated using the extended COM theory by integrating dispersion characteristics parameters into the COM model. We compared its results with those obtained via FEM analysis to confirm the proposed model's validity. We found that the variation in stop band edge frequency related to gyroscope effect reached the maximum value with a zero reflectivity value. For split IDT, the sensitivity of gyroscope effect is 0.036 Hz/rad/s with a lower than 1% normalized thickness. Conversely, the value of sensitivity was almost zero for bidirectional IDT and electrode width controlled single-phase unidirectional transducer (EWC/SPUDT).
关键词： interdigital transducer,surface acoustic wave,gyroscopic effect
更新于2025-09-23 15:23:52
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Monitoring of Film Qualities of Amorphous SiO2 films/Si(100) Substrates by Measuring Bulk and Surface Acoustic Waves in Terms of Brillouin Spectroscopy
摘要： Acoustic properties of amorphous SiO2 thin films deposited on the Si(100) substrate were investigated by using Brillouin spectroscopy. The Brillouin spectrum was obtained by tilting the sample to investigate both the longitudinal acoustic (LA) mode and the surface acoustic wave (SAW) modes. Sound velocities of both modes, the two elastic moduli (longitudinal and shear moduli), and the Poisson ratio of the film could be obtained by combining the Brillouin data and the measured refractive index. The longitudinal sound velocity and the longitudinal elastic modulus increased with increasing Ar ratio in the Ar:O2 gas mixture, which was attributed to the better stoichiometry of the film grown at higher Ar ratio.
关键词： Brillouin scattering,Surface acoustic wave,SiO2 film
更新于2025-09-23 15:22:29
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[ACM Press the 2017 2nd International Conference - Wuhan, China (2017.11.07-2017.11.09)] Proceedings of the 2017 2nd International Conference on Communication and Information Systems - ICCIS 2017 - Effect of Concentration on Surface Acoustic Wave Velocity in A Rayleigh-type Biosensor
摘要： To predict the propagation velocity of different concentrations of bovine serum albumin (BSA) in a Rayleigh-type biosensor, we derived a new calculation method for a Rayleigh surface acoustic wave (SAW) device. The method can calculate propagation velocities of leaky Rayleigh waves and Rayleigh waves when liquid is placed in the groove of a Rayleigh-type SAW device. Different concentration of BSA proteins were used to evaluate the effect of these concentrations. In this study, we used different concentrations of BSA and a Rayleigh-type SAW device consisted of grooves of 0.25 mm width and 0.26 mm height and grooves of 0.40 mm width and 0.25 mm height, quartz as the substrate and interdigital transducers (IDT) with a 25.00 mm distance. The frequency of the Rayleigh-type SAW device was set to 157.6 MHz. Our data suggests that the propagation velocity of SAWs depends mainly upon BSA protein concentration and the size of groove. At the same concentration of BSA, the propagation acoustic wave velocity of BSA depends on the size of groove. The results showed the 0.40 mm width-0.25 mm height groove was more suitable than the 0.25 mm width-0.26 mm height groove for studying the propagation velocity of wave with liquid in a Rayleigh-type SAW device. With the propagation velocity decreased when the concentration of BSA protein increased.
关键词： Surface acoustic wave (SAW),Rayleigh-type SAW device,Leaky Rayleigh wave,Bovine serum albumin (BSA),Rayleigh wave
更新于2025-09-23 15:21:01
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Single-photon emission from single-electron transport in a SAW-driven lateral light-emitting diode
摘要： The long-distance quantum transfer between electron-spin qubits in semiconductors is important for realising large-scale quantum computing circuits. Electron-spin to photon-polarisation conversion is a promising technology for achieving free-space or fibre-coupled quantum transfer. In this work, using only regular lithography techniques on a conventional 15 nm GaAs quantum well, we demonstrate acoustically-driven generation of single photons from single electrons, without the need for a self-assembled quantum dot. In this device, a single electron is carried in a potential minimum of a surface acoustic wave (SAW) and is transported to a region of holes to form an exciton. The exciton then decays and creates a single optical photon within 100 ps. This SAW-driven electroluminescence, without optimisation, yields photon antibunching with g(2)(0) = 0.39 ± 0.05 in the single-electron limit (g(2)(0) = 0.63 ± 0.03 in the raw histogram). Our work marks the first step towards electron-to-photon (spin-to-polarisation) qubit conversion for scaleable quantum computing architectures.
关键词： quantum computing,GaAs quantum well,electron-spin qubits,surface acoustic wave,single-photon emission
更新于2025-09-23 15:19:57
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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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Nondestructive Evaluation of Thermal Aging in Al6061 Alloy by Measuring Acoustic Nonlinearity of Laser-Generated Surface Acoustic Waves
摘要： The structures in high-temperature environments are prone to undergo hardening and embrittlement as a result of thermal aging; this can cause variations in their mechanical properties. Because these changes occur at the microstructural level, it is difficult to evaluate them through linear ultrasonic techniques. In this work, a surface acoustic wave (SAW) was used to measure and compare the acoustic nonlinearity and mechanical properties of Al6061 alloys heat-treated at 220°C for different durations (0 min, 20 min, 40 min, 1 h, 2 h, 10 h, 100 h, 1000 h). The SAW was generated by a pulsed laser and then received by an interferometer. Moreover, the yield strength, ultimate strength, and elongation to failure were measured by tensile tests. The results demonstrate that the critical variations in the mechanical properties can be detected by monitoring the variation features in the acoustic nonlinearity. Transmission electron microscopy images were captured to observe the microstructural changes, which shows that the acoustic nonlinearity varied according to the change in the precipitation phase. This supports the acoustic nonlinearity measurement using the laser-generated SAW being an effective technique for the fully noncontact nondestructive evaluation of material degradations as well as changes in mechanical properties.
关键词： surface acoustic wave,material degradation,laser,heat treatment,mechanical property,thermal aging,nonlinear parameter,precipitation,acoustic nonlinearity
更新于2025-09-19 17:13:59
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Time-frequency analysis of laser-excited surface acoustic waves based on synchrosqueezing transform
摘要： Laser-excited surface acoustic wave (LSAW) techniques can realize the measurement of surface properties through dispersion curve inversion. In addition to the conventional phase spectrum method, time-frequency analysis can also be used as a calculation tool for the dispersion curve. An accurate time-frequency analysis method is important in precisely inverting the surface properties. In this paper, synchrosqueezing transform (SST) is applied to the analysis of LSAW. By comparing the processing results of the constructed LSAW signal, SST shows higher time-frequency resolution and robustness than other common time-frequency analysis algorithms. Finite element model is used to simulate the propagation of LSAW in the film/substrate structure. And SST is used to calculate the dispersion curve of SAW information extracted during the simulation. A fast algorithm is introduced, where the film thickness is initially estimated by calculating the midrange. Through inversion, the resulting film thickness error is only 1.20% from the theoretical value. Therefore, SST is an effective tool for analyzing LSAW and calculating its dispersion curve.
关键词： Synchrosqueezing transform,Surface acoustic wave,Surface properties,Dispersion curve
更新于2025-09-19 17:13:59
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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