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Distributed Strain Sensing Using Electrical Time Domain Reflectometry With Nanocomposites
摘要： The objective of this study is to validate distributed strain sensing using electrical time domain reflectometry (ETDR) with multi-walled carbon nanotube (MWCNT)-based thin film sensing elements. The proposed ETDR sensor composed of two types of transmission lines: parallel-wire-type transmission line and parallel-plate-type transmission line with MWCNT-based sensing elements. The hypothesis was that the greater strain-induced impedance changes of the nanocomposite would enhance ETDR sensing performance. In this paper, four different types of ETDR sensing elements were subjected to one-cycle uniaxial tensile strains to validate strain sensing. Three sensing elements were then integrated in an ETDR setup, and strain patterns were applied for validating their distributed strain sensing behavior.
关键词： transmission line,Carbon nanotubes,thin film,strain sensing,electrical time domain reflectometry
更新于2025-09-09 09:28:46
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[IEEE 2018 International Conference on Optical MEMS and Nanophotonics (OMN) - Lausanne (2018.7.29-2018.8.2)] 2018 International Conference on Optical MEMS and Nanophotonics (OMN) - Elastic Strain Engineering for Ultralow Mechanical Dissipation
摘要： Extreme stresses can be produced in nanoscale structures, a feature which has been used to realize enhanced materials properties, such as the high mobility of silicon in modern transistors. Here we show how nanoscale stress can be used to realize exceptionally low mechanical dissipation, when combined with “soft-clamping” — a form of phononic engineering. Specifically, using a non-uniform phononic crystal pattern, we colocalize the strain and flexural motion of a free-standing Si3N4 nanobeam. Ringdown measurements at room temperature reveal string-like modes with quality (Q) factors as high as 800 million and Q × frequency exceeding 1015 Hz.
关键词： optomechanics,strain engineering,nanomechanics
更新于2025-09-09 09:28:46
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Simultaneous measurement of strain, temperature and refractive index based on a fiber Bragg grating and an in-line Mach–Zehnder interferometer
摘要： A simple sensor for simultaneous measurement of strain, temperature and refractive index (RI) is proposed and demonstrated. The sensor is based on a fiber Bragg grating (FBG) combined with an in-line Mach-Zehnder interferometer (MZI). MZI is formed by introducing a section of thinned core fiber (TCF) between two segments of multimode fiber (MMF). The two MMFs act as couplers that can excite high-order modes and recouple core mode and high-order modes into lead-out SMF, the function of this structure is to form inter-modes interference. The maximum interference fringe visibility exceed 20 dB. By monitoring the wavelength shifts of FBG and interference dips, simultaneous measurement of strain, temperature and RI can be achieved. The experimental results show that the maximum sensitivity of the sensor for strain, temperature and RI are -2.14 pm/με, 35.2 pm/°C and 32.93 nm/RIU, respectively. The proposed sensor has the advantages of easy fabrication, high fringe visibility and high sensitivities. Therefore, it has potential applications in multi-parameters simultaneous measurement.
关键词： Temperature,Refractive index,Mach-Zehnder interferometer,Strain,Fiber Bragg grating
更新于2025-09-09 09:28:46
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[ASME ASME 2018 International Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Microsystems - San Francisco, California, USA (Monday 27 August 2018)] ASME 2018 International Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Microsystems - Investigation of the Effects of High Temperature Aging on the Mechanical Behavior of Lead Free Solders
摘要： Lead free solders are renowned as interconnects in electronic packaging due to their relatively high melting point, attractive mechanical properties, thermal cycling reliability, and environment friendly chemical properties. The mechanical behavior of lead free solders is highly dependent on the operating temperature. Previous investigations on mechanical characterization of lead free solders have mainly emphasized stress-strain and creep testing at temperatures up to 125 °C. However, electronic devices, sometimes, experience harsh environment applications including well drilling, geothermal energy, automotive power electronics, and aerospace engines where solders are exposed to very high temperatures from 125-200 °C. Mechanical properties of lead free solders at elevated temperatures are limited. In this work, we have investigated the mechanical behavior SAC305 (96.5Sn-3.0Ag-0.5Cu) and SAC_Q (SAC+Bi) lead free solders at extreme high temperatures up to 200 °C. Stress-strain tests were performed on reflowed uniaxial specimens at four elevated temperatures (T = 125, 150, 175, and 200 °C). In addition, changes of the mechanical behavior of these alloys due to isothermal aging at T = 125 oC have been studied. Extreme care has been taken during specimen preparation so that the fabricated solder uniaxial test specimens accurately reflect the solder material microstructures present in actual lead free solder joints. High temperature tensile properties of the solders including initial modulus, yield stress, and ultimate tensile strength have been compared. As expected, our results show substantial degradations of the mechanical properties of lead-free solders at higher temperatures. With prior aging, these degradations become even more significant. Comparison of the results has shown that the addition of Bi to traditional SAC alloys improves their high temperature properties and significantly reduces their aging induced degradations.
关键词： Yield Stress,Ultimate Tensile Strength,Stress-Strain Curve,SAC alloy,Modulus,Lead-Free Solder,Aging
更新于2025-09-09 09:28:46
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[IEEE 2018 IEEE Photonics Conference (IPC) - Reston, VA, USA (2018.9.30-2018.10.4)] 2018 IEEE Photonics Conference (IPC) - Cavity Optomechanical Photothermal Sensors
摘要： We experimentally demonstrate a cavity optomechanical sensor that is actuated with gradient optical forces. The sensor can detect incident radiation via absorption and resulting photothermally-induced frequency shifts of the nanomechanical oscillator. Analysis suggests that nanostrain sensitivity and fJ-level energy detection are possible.
关键词： Photothermal effects,Strain measurement,Nanoelectromechanical systems,Nanosensors,Optical waveguides,Nanophotonics
更新于2025-09-09 09:28:46
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Strain-tunable quantum integrated photonics
摘要： Semiconductor quantum dots are crucial parts of the photonic quantum technology toolbox, as they show excellent single photon emission properties in addition to their potential as solid state qubits. Recently, there has been an increasing effort to deterministically integrate single semiconductor quantum dots into complex photonic circuits. Despite rapid progress in the field, it remains challenging to manipulate the optical properties of waveguide-integrated quantum emitters, in a deterministic, reversible, and non-intrusive manner. Here we demonstrate a new class of hybrid quantum photonic circuits combining III-V semiconductors, silicon nitride, and piezoelectric crystals. Using a combination of bottom-up, top-down, and nanomanipulation techniques, we realize strain tuning of a selected, waveguide-integrated, quantum emitter and a planar integrated optical resonator. Our findings are an important step toward realizing reconfigurable quantum integrated photonics, with full control over the quantum sources and the photonic circuit.
关键词： ring resonator,nanowires,strain tuning,quantum dot,single photon,quantum integrated photonics
更新于2025-09-09 09:28:46
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The formation mechanism of globally biaxial strain in He <sup>+</sup> implanted silicon-on-insulator wafer based on the plastic deformation and smooth sliding of buried SiO <sub/>2</sub> film
摘要： In this paper, we proposed an approach to obtain a globally biaxially strained silicon-on-insulator (SOI) wafer, and the strain mechanism was discussed. By this process, both biaxially tensile and compressive strained SOI (sSOI) can be obtained. The strain introduced into the SOI layer is mainly contributed by the plastic deformation of the buried SiO2 film caused by annealing with the deposition of a high-stress SiN film. Furthermore, He+ implantation at the interface between SiO2 and the substrate Si layer is confirmed to effectively enhance the strain by the sliding of the buried SiO2 at the SiO2-substrate Si interface. Raman spectroscopy shows that the strain of the He+ implanted sSOI has a significant enhancement of more than 300% compared with the unimplanted sSOI.
关键词： silicon-on-insulator,biaxial strain,plastic deformation,He implantation,SiO2 film
更新于2025-09-09 09:28:46
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Piezophototronic Effect Modulated Multilevel Current Amplification from Highly Transparent and Flexible Device Based on Zinc Oxide Thin Film
摘要： In this work, a strain modulated highly transparent and flexible ZnO/Ag-nanowires/polyethylene terephthalate optoelectronic device is developed. By utilizing the applied external strain-induced piezophototronic effects of a ZnO thin film, a UV-generated photocurrent is tuned in a wide range starting from 0.01 to 85.07 μA and it is presented in a comprehensive map. Particularly, the performance of the device is effectively enhanced 7733 times by compressive strain, as compared to its dark current in a strain-free state. The observed results are explained quantitatively based on the modulation of oxygen desorption/absorption on the ZnO surface under the influence of applied strains. The presented simple optoelectronic device can be easily integrated into existing planar structures, with potential applications in highly transparent smart windows, wearable electronics, smartphones, security communication, and so on.
关键词： flexible,piezophototronic,amplification,transparent,strain
更新于2025-09-09 09:28:46
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Modeling charge density in AlGaN/AlN/InGaN/GaN-based double heterostructures including InGaN layer strain relaxation
摘要： An analytical model is presented to calculate the two-dimensional electron gas (2DEG) density and barrier height of bare surface AlGaN/AlN/InGaN/GaN double heterostructures, which use InGaN as the conducting layer. The basic model is derived from electrostatic analysis of the di?erent material interfaces. The e?ect of strain relaxation in the InGaN layer is also incorporated here. Further, the impact of a two-dimensional hole gas at the InGaN/GaN interface, formed when the InGaN layer thickness is high, has been considered. The presented results are seen to agree with the available experimental results. Thus, this model can be a useful tool in the design and modeling of InGaN-based III-nitride heterostructures.
关键词： two-dimensional hole gas,AlGaN/InGaN/GaN heterostructure,strain relaxation,two-dimensional electron gas
更新于2025-09-09 09:28:46
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Heterogeneity governs diameter-dependent toughness and strength in SiC nanowires
摘要： Using a combination of density functional theory and molecular dynamics simulations, this paper reveals the atomistic origin of diameter-dependent extreme mechanical behavior of [111] 3C-SiC nanowires obtained from an energy-based framework. Our results suggest that heterogeneity in atomic stress and variations in diameter-dependent potential-energy density have a profound impact on extreme mechanical properties in the nanowires. The heterogeneity in stress evolves from the nonuniform bond lengths mediated by low coordinated surface atoms—and it penetrates the entire cross section in thinner nanowires and constitutes the atomistic basis for their large reduction in fracture strain, toughness, and strength. Although stress heterogeneity is substantially higher in ultrathin nanowires, its intensity drops and saturates rapidly in larger nanowires following a nonlinear dependence on diameter. The maximum stress heterogeneity in a cross section localizes crack nucleation at the core in ultrathin nanowires but near the surface in larger nanowires. Moreover results show that stiffness, toughness, strength, and fracture strain of the nanowires increase nonlinearly with increasing diameter and saturate at a lower value compared to bulk SiC. In addition to resolving wide discrepancies in the reported values of the ?rst-order elastic modulus in SiC nanowires, the ?ndings highlight heterogeneity as a critical factor for inducing diameter-dependent extreme mechanical behavior in brittle nanowires.
关键词： heterogeneity,atomic stress,strength,toughness,potential-energy density,fracture strain,SiC nanowires,diameter-dependent,mechanical properties
更新于2025-09-09 09:28:46