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Camera array-based digital image correlation for high-resolution strain measurement
摘要： Digital image correlation (DIC) is a well-known technique for non-contact, non-destructive, full-field deformation measurement in experimental solid mechanics. Although DIC has been widely used in science and engineering, the resolution of strain measurement with DIC is limited by imaging resolution and is much lower than that obtained with a strain gauge. To achieve a breakthrough in strain measurement using DIC, a camera array-based DIC method is proposed herein for high-resolution strain measurement. Twenty-five industrial cameras were assembled into a plane array, with each camera capturing a part of the specimen. A novel calibration-based image stitching method is proposed and was applied to these images and their corresponding displacement fields. The strain field was then calculated based on the stitched displacement fields. The use of the camera array greatly improved the measurement spatial resolution of DIC and made high-resolution strain measurement possible. Both static error analysis and four point-bending experiments were performed to demonstrate the feasibility and effectiveness of the proposed method, and a full-field strain resolution of 10 με was achieved.
关键词： displacement field stitching,camera array,Digital image correlation,image stitching,high-resolution strain measurement
更新于2025-09-23 15:21:01
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High-sensitivity strain sensor with an in-fiber air-bubble Fabry-Perot interferometer
摘要： We present a laser machining method for fabricating an all-fiber pillar-in-bubble Fabry-Perot interferometer (FPI), which is used for strain sensors with high sensitivity. The micro-structure of the air-bubble is fully controllable, especially the cavity length and sidewall thickness. The measured sensitivity of this strain sensor is as high as 56.69 pm/με, which is several times higher than that of most FPI strain sensors reported to date. This sensor also has a low-temperature sensitivity of 0.682 pm/°C, reducing the cross-sensitivity between tensile strain and temperature to 0.012 με/°C. Furthermore, such a sensor has the benefits of flexible design, simple fabrication, and high reproducibility, making it attractive for practical applications.
关键词： high sensitivity,fiber optic,Fabry-Perot interferometer,laser machining,strain sensor
更新于2025-09-23 15:21:01
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Theoretical characterization of strain and interfacial electronic effects in donor-acceptor bilayers of 2D transition metal dichalcogenides
摘要： Amine Slassi1, Jér?me Cornil1,* E-mail : jerome.cornil@umons.ac.be Bilayers of 2D Transition Metal Dichalcogenides 1Laboratory for Chemistry of Novel Materials, University of Mons, BE-7000 Mons, Belgium Theoretical Characterization of Strain and Interfacial Electronic Effects in Donor-Acceptor Two-dimensional (2D) materials and their van der Waals (vdW) stacked hetero-structures are promising candidates for highly efficient (opto)-electronic applications. The performance of vdW these properties are affected when building a bilayer. We focus on MoS2-based bilayers, including MoS2/MoS2, WS2/MoS2, MoSe2/MoS2 and WSe2/MoS2 structures. The impact of properties of two-dimensional transition metal dichalcogenide (TMDs) monolayers and the way vacancies on the interlayer interactions is also investigated. The main finding of our calculations first?principle calculations, we have explored systematically the structural and electronic is that changes in the properties of 2D monolayers upon building stack do occur and are driven by heterostructures in devices strongly depend on electronic processes at their interfaces. Here, using both strain effects and interfacial electronic processes.
关键词： defect vacancy,first-principles calculations,vdW heterostructures,electronic processes,strain effects
更新于2025-09-23 15:21:01
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Tensilely Strained Ge Films on Si Substrates Created by Physical Vapor Deposition of Solid Sources
摘要： The development of Si-compatible active photonic devices is a high priority in computer and modern electronics industry. Ge is compatible with Si and is a promising light emission material. Nearly all Ge-on-Si materials reported so far were grown using toxic precursor gases. Here we demonstrate the creation of Ge films on Si substrates through physical vapor deposition of toxin-free solid Ge sources. Structural characterization indicates that a high tensile strain is introduced in the Ge film during the deposition process. We attribute the presence of such a tensile strain to the difference in thermal expansion coefficient between Si and Ge. A Ge peak, centered at ~2100 nm, is evident in the photoluminescence spectra of these materials, which might result from direct band gap photoluminescence alone, or from superposition of direct band gap and indirect band gap photoluminescence. These Ge-on-Si materials are therefore promising in light emission applications.
关键词： tensile strain,Si substrates,physical vapor deposition,Ge films,photoluminescence
更新于2025-09-23 15:21:01
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[ACM Press the International Conference - San Diego, California (2018.11.05-2018.11.08)] Proceedings of the International Conference on Computer-Aided Design - ICCAD '18 - Strain-aware performance evaluation and correction for OTFT-based flexible displays
摘要： Organic thin-?lm transistors (OTFTs) are widely used in ?exible circuits, such as ?exible displays, sensor arrays, and radio frequency identi?cation cards (RFIDs), because these technologies offer features such as better ?exibility, lower cost, and easy manufacturability using low-temperature fabrication process. This paper develops a procedure that evaluates the performance of ?exible displays. Due to their very nature, ?exible displays experience signi?cant mechanical strain/stress in the ?eld due to the deformation caused during daily use. These deformations can impact device and circuit performance, potentially causing a loss in functionality. This paper ?rst models the effects of extrinsic strain due to two fundamental deformations modes, bending and twisting. Next, this strain is translated to variations in device mobility, after which analytical models for error analysis in the ?exible display are derived based on the rendered image values in each pixel of the display. Finally, two error correction approaches for ?exible displays are proposed, based on voltage compensation and ?exible clocking.
关键词： Organic thin-?lm transistors (OTFTs),performance evaluation,error correction,strain modeling,?exible displays
更新于2025-09-23 15:21:01
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Dielectric relaxation and resistive switching of Bi0.96Sr0.04Fe0.98Co0.02O3/CoFe2O4 thin films with different thicknesses of the Bi0.96Sr0.04Fe0.98Co0.02O3 layer
摘要： Bi0.96Sr0.04Fe0.98Co0.02O3/CoFe2O4(BSFCO/CFO) bilayered thin films with different thicknesses of the BSFCO layer are synthesized on FTO/glass substrates by chemical solution deposition method (CSD). The influence of BSFCO thickness on the microstructure, dielectric relaxation, ferroelectric properties and resistive switching (RS) of the thin films are researched. Strain exists in the prepared thin films and gives rise to structural distortion, which has an effect on charged defects and ferroelectric polarization. Dielectric relaxation that is closely related to the interfacial polarization at the BSFCO/CFO interface is observed, and the dielectric loss peaks along with decreasing intensity shift to high frequency with decreasing strain. The Maxwell-Wagner two-layer model is adopted to investigate the mechanism of dielectric relaxation, and the relaxation time τ is calculated and it shown to be directly proportional to the strain. It is found that the dielectric properties, including low dielectric loss, can be improved by controlling the BSFCO layer thickness. The ferroelectric properties improve with the decreasing strain, the 12-BSFCO/CFO thin film possesses a large Pr~102.9 μC/cm2 at 660 kV/cm. The observed resistive switching (RS) behavior is attributed to the interfacial conduction mechanism, it is found that strain-dependent the ferroelectric polarization switching modulates the width of depletion layer and the height of potential barrier at the interface, resulting in the different resistance states.
关键词： dielectric relaxation,bilayered thin film,BiFeO3,resistive switching,strain
更新于2025-09-23 15:21:01
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Strain Effect in Highly-Doped n-Type 3C-SiC-on-Glass Substrate for Mechanical Sensors and Mobility Enhancement
摘要： This work reports the strain effect on the electrical properties of highly doped n-type single crystalline cubic silicon carbide (3C-SiC) transferred onto a 6-inch glass substrate employing an anodic bonding technique. The experimental data shows high gauge factors of (cid:1)8.6 in longitudinal direction and 10.5 in transverse direction along the [100] orientation. The piezoresistive effect in the highly doped 3C-SiC film also exhibits an excellent linearity and consistent reproducibility after several bending cycles. The experimental result is in good agreement with the theoretical analysis based on the phenomenon of electron transfer between many valleys in the conduction band of n-type 3C-SiC. Our finding for the large gauge factor in n-type 3C-SiC coupled with the elimination of the current leak to the insulated substrate could pave the way for the development of single crystal SiC-on-glass based MEMS applications.
关键词： piezoresistance,wafer bonding,silicon carbide,MEMS,strain engineering
更新于2025-09-23 15:21:01
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A Synergy of Strain Loading and Laser Radiation in Determining the High-Performing Electrical Transports in the Single Cu-Doped SnSe Microbelt
摘要： Semiconducting microbelts are key components of the thermoelectric micro-devices, and their electrical transport properties play significant roles in determining the thermoelectric performance. Here, we report heavily Cu-doped single-crystal SnSe microbelts as potential candidates employed in thermoelectric micro-devices, fabricated by a facile solvothermal route. The considerable Cu-doping concentration of ~11.8 % up to the solubility contributes to a high electrical conductivity of ~416.6 S m-1 at room temperature, improved by one order of magnitude compared with pure SnSe (38.0 S m-1). Meanwhile, after loading ~1 % compressive strain and laser radiation, the electrical conductivity can be further improved to ~601.9 S m-1 and ~589.2 S m-1, respectively, indicating great potentials for applying to thermoelectric micro-devices. Comprehensive structural and compositional characterizations indicate that the Cu+ doping state provides more hole carriers into the system, contributing to the outstanding electrical conductivity. Calculations based on first-principle density functional theory reveal that the heavily doped Cu lowers the Fermi level down into the valence bands, generating holes, and the 1 % strain can further reduce the bandgap, strengthening the ability to release holes, and, in turn, leading to such an excellent electrical transport performance. This study fills the gaps of finding novel materials as potential candidates employed in the thermoelectric micro-devices and provides new ideas for micro/nanoscale thermoelectric material design.
关键词： Cu-doping,tin selenide,electrical transport performance,laser radiation,strain loading
更新于2025-09-23 15:19:57
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Development of laser speckle blood flowmeter for evaluating the physiological function of skin
摘要： Objective: We developed and demonstrated laser speckle ?owgraphy (LSFG) for two-dimensional (2D) skin blood ?ow (SBF) measurements to facilitate the noninvasive comparisons of SBF between individuals. Approach: By using morphing technology with a face mesh to compare SBF spatial distributions among individuals, we examined the practicability of SBF measurement with LSFG. Main results: (1) The uniformity of SBF measurement was demonstrated by examinations at different distances and angles for healthy subjects. (2) Mean blur rate (MBR)—a blood ?ow index of LSFG—exhibited signi?cant correlation with the thermal diffusion method (TDM)—an established blood ?ow measurement method—suggesting that MBR is an effective index of SBF. (3) Blowout time, the half-width duration/duration of one cardiac cycle, exhibited signi?cant negative correlation with age and positive correlation with stratum corneum hydration. Signi?cance: These results suggest that LSFG is useful for evaluating SBF-related skin properties, and it has signi?cant potential in medicine and cosmetology.
关键词： aging,stratum corneum hydration,skin blood ?ow,laser speckle ?owgraphy,morphing,strain-gauge plethysmography,thermal diffusion
更新于2025-09-23 15:19:57
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Plastic strain localization induced by microstructural gradient in laser cladding repaired structures
摘要： Laser Cladding is an additive manufacturing technology well suited for the repair of complex metallic components. The repair is a two-step process: first, one removes the worn region and then, the initial geometry is reconstructed locally. The aim of this work is to study the influence of the microstructural gradient on the strain localization in repaired structures. More precisely, we perform in-situ SEM tensile tests completed by EBSD observations of the microstructure in the interface neighborhood between the base material and the repaired region. Furthermore, we monitor the evolution of the local plastic strain distribution at the grain level until failure. This is performed by Digital Image Correlation methods and superposition of grains contours and strain maps. The observations of grain size and plasticity are compared with predictions provided by a Hall-Petch model. The study emphasizes the importance of the microstructural gradient in the vicinity of reparation interface, more precisely it reveals that this gradient induce multiaxial strains and that the strain localization phenomenon is governed mainly by a grain size effect.
关键词： Laser Cladding repair,Additive manufacturing,SEM in-situ tests,strain localization,microstructural gradient
更新于2025-09-23 15:19:57