Equibiaxial Stretching Device for High Magnification Live-Cell Confocal Fluorescence Microscopy.

Herein, the effect of tensile and compressive stress on the performance of a 3 × 3 InSb array as an infrared photodetector is investigated. At first, the effect of mesh sizes on simulated results is evaluated and the results are validated with a good agreement. It is shown that the main effect of stress is related to the Γ (bandgap) point of the band structure. This shift causes the densities of intrinsic and minority carriers to decrease in the case of tensile stress and increase in the case of compressive stress. Using a 3D simulation, it is investigated that tensile stress reduces the dark current while compressive stress induces that. However, it is an interesting result that an increment in applied compressive stress interrupts the InSb photodetector performances and vice versa tensile stress helps the photocurrent to have a lower dark current. So, these results can be used to manage the dark current in the field of the photodetector. Finally, the crosstalk of the simulated structure as one of its main characteristics is calculated.

A novel cylindrical composition-gradient electrode is considered to be one of most potential structures in lithium-ion battery. To investigate the mechanism of a cylindrical composition-gradient electrode under potentiostatic operation, we take Li1.2(Mn0.62Ni0.38)0.8O2 for example. The effects of the three main factors, i.e., diffusion coefficient, Youngs modulus, partial molar volume of solute, on the stress field in the cylindrical electrode are discussed. Each of the three material parameters is assumed to be a linear function of the distance from the center to surface. The small deformation theory and thermodynamic theory are employed to establish the mathematical model of composition-gradient cylindrical electrode. The mechanics equations and diffusion equation of cylindrical electrode are derived for an inhomogeneous material in plane strain condition. By comparing with single-phase electrode, it is found that Youngs modulus increasing from the center to the surface greatly reduces the max tensile radial stress and tensile hoop stress and changes the location of max radial stress since the radial displacement of the center is restricted. The time for the lithium-ions to reach the center is longer and the tensile stress near the center decreases at dimensionless time =0.0574 when diffusion coefficient decreases along the radial direction. Owing to the smaller diffusion coefficient at the surface, there is a reduction in the number of lithium-ions through the unit area in unit time when their corresponding concentration gradients are the same. The variation of partial molar volume means that the volume expansion caused by the intercalation of lithium-ions decreases along the radial direction. Therefore the partial molar volume decreasing along the radial direction considerably reduces the radial stress and the distribution of tangential stress becomes flat. The center point is picked, showing the development of hoop stress. The results show that the hoop stress increases and reaches a maximal value close to the dimensionless time =0.0574. Maximal tensile hoop stress at the center is reduced in an inhomogeneous material. The tensile hoop stress turns into compressive stress over time when elastic modulus and partial molar volume are denoted with E(r) and (r) respectively. The results indicate that the cylindrical composition-gradient electrode with core enriched Ni and edge enriched Mn reduces the max tensile radial stress and tensile hoop stress. It is an efficient way to avoid mechanical fracture in electrode since evidence has accumulated that tensile stress is the lead cause of crack in electrode. The result also provides useful guidance for mitigating the stresses in a cylindrical electrode.

The analysis of loading on the chloride penetration into concrete is very important. In this study, we confirmed that the chloride penetration rates for the plain and BFS concrete were increased by 47% and 89% under the compressive stress, respectively. Under the tensile stress, those for the plain and BFS concrete were increased by 29% and 77%, respectively. The diffusion coefficient of BFS concrete was lower than the conventional one with no BFS no loads and stress states. Under the compressive stress, the diffusion coefficient for BFS concrete was higher with increasing stress as well as the plain concrete. Under the tensile stress, the diffusion coefficient for BFS and plain concrete showed higher values with increasing stress. We investigated the effect of the difference of specific surface on diffusion coefficient. As a result, the larger specific surface of BFS exhibited the lower diffusion coefficient. This tendency showed remarkably under the high stress conditions. We confirmed that the diffusion coefficient was lower with increasing the ratio of substitution BFS. This result was the same even under the compressive and tensile stress conditions. The chloride penetration depth was distributed uniformly under the compressive stress or no stress. However, in the case of the tensile stress, the diffusion distribution of chloride ion penetrated into concrete was no uniform, and I showed the prominent characteristics. This result indicates that the analysis using by average values is not proper under the stress conditions.

Effects of compressive and tensile stress on the growth mode of epitaxial oxide films

The evolution of mechanical stress resulting from electromigration in a polycrystalline thin film Al interconnect is simulated as a function of current density assuming zero stress boundary conditions. A polygranular cluster region is introduced into lines with otherwise bamboo microstructures, and results in a pair of atomic flux divergence sites and a tensile-compressive stress dipole. In the tensile stress region, the atomic diffusivity is higher than that in the compressive stress region, leading to more rapid electromigration, so that the tensile stress is initially slightly larger than the compressive stress in the dipole. Eventually though, the tensile stress drops to a small value while the compressive peak in the cluster increases above its initial values due to a stress buildup at the end of the cluster. For a given line, the maximum compressive stress resulting from electromigration is larger than the maximum tensile stress. Increasing the current density leads to an increasing difference in the maximum compressive and tensile stresses.

Solution-deposited ferroelectric films often are under mechanical stress due to the difference in thermal expansion coefficients between films and substrate materials. Knowledge of how stress changes the ferroelectric response under different actuation conditions is essential when selecting a substrate for film deposition. Here, a comparative study of the ferroelectric properties of lead zirconate titanate thin films on transparent fused silica glass and sapphire substrates is presented. Sapphire exerts a compressive in-plane stress on the film, favoring an out-of-plane domain orientation, while fused silica causes tensile in-plane stress and a predominantly in-plane domain configuration. As expected, the out-of-plane polarization is high under in-plane compressive stress but reduced by a factor of nearly 4 by in-plane tensile stress. In contrast, the in-plane polarization shows an unexpectedly weak stress dependence. It is larger by only about 10% under tensile stress compared to compressive stress. Permittivity increases when the major domain orientation does not coincide with the electric field. The observations are explained based on a model taking into account the crystallographic structure of the film.

Free volume and alcohol transport properties of PDMS membranes: Insights of nano-structure and interfacial affinity from molecular modeling

Over the past decade, the certified power conversion efficiency of perovskite solar cells (PSCs) has increased to 26.1%. However, phase instability originating from lattice strains, has limited their commercialization. Strains will inevitably be generated during the PSC fabrication and service process due to the “soft lattice” nature of halide perovskites. In particular, flexible PSCs are subjected to not only mechanical tensile and compressive loads, but also suffer from thermal stresses. In this study, strain-induced changes in the phase stability and the corresponding optoelectronic properties of CsPbI3−xBrx (CsPbI3, CsPbBr3, and CsPbI2Br) systems under tensile and compressive stresses were investigated using first-principles calculations. The results showed that compressive stresses reduce the bandgap value and increase the light absorption coefficient; thus, the optoelectronic performance is improved, whereas the light absorption coefficient decreases regardless of how the bandgap changes under tensile stresses. Moreover, under the same stress, the tensile strain value was twice that of the compressive strain, and the critical value of the transition from the cubic to tetragonal phase was lower, indicating that phase stability was worse under tensile stresses. Therefore, during the fabrication of PSCs, the tensile stress state should be adjusted to the compressive stress state, which is favorable for enhancing PSCs photovoltaic performance and phase stability. The results not only provide direct evidence of tensile and compressive strains influencing the phase stability and optoelectronic property changes in halide perovskites, but also highlight lattice-strain tailoring for the composition design, process optimization, and interface engineering of efficient and stable PSCs.

Apparent fracture toughness of Si 3N 4-based laminates with residual compressive or tensile stresses in surface layers

The three-dimensional periacetabular bone architecture has been established by sectioning multiple pelves in coronal, parasagittal, and horizontal planes. Maximum compressive and tensile stresses were determined by a finite element model of the acetabulum. The architecture is symmetric in a given specimen, and quite similar from specimen to specimen. The subchondral bone is always much thicker than the trabecular bone, and greater stresses were predicted with the model in the subchondral bone (the magnitude of tensile stresses being greater than the magnitude of compressive stresses). There are two general systems of periacetabular trabeculae: the more prominent and regular is generally radial to the center of the acetabulum, and the less prominent, less regular is in more or less concentric spheres about the acetabulum. The direction of predicted compressive stresses corresponded to the radial system and the direction of the predicted tensile stresses corresponded to the concentric system; compressive stresses in trabecular bone were of higher magnitude than tensile stresses.

Toward understanding the surface morphology and microscopic mechanical properties of asphalt after experiencing tensile and compressive stress

Microlens arrays (MLAs) nowadays are critical micro-optical components and they can be applied in many application fields, such as optical communication systems and flat panel display modules. This article describes a novel approach to the fabrication of tunable, highly reliable, and uniform polydimethylsiloxane (PDMS) MLAs. A polydimethylsiloxane (PDMS) membrane is bonded to a micro-milled poly(methyl methacrylate) (PMMA) microfluidic chip and exposed to silicone oil of a specific viscosity. Molecules in the oil insert themselves into the molecular structure of the PDMS membrane, causing it to swell and subsequently form dome-shaped MLAs. From our experiments, we derived the following conclusions. First, the homogeneous swelling of the PDMS resulted in MLAs with a high numerical aperture (0.5), high uniformity illumination (CV of the illumination intensity is between 2.5%∼5.1%), and high uniformity (CV of sag height of MLAs is less than 0.05). Second, the shorter molecular chains in low-viscosity oils diffused more readily into the PDMS membrane, which increased the effects on swelling, resulting in MLAs with higher sag height and higher numerical aperture. For example, the 5 cst silicone oil resulted in sag height of 191 µm with NA of 0.50, whereas the 100 cst silicone oil resulted in sag height of 86 µm with numerical aperture of 0.33. Finally, the integrated mixer module enabled the simultaneous tuning of the 7 × 7 MLAs simply by adjusting the injection flow rates of the constituent silicone oils.

This paper investigates the basic deflection properties of polydimethylsiloxane (PDMS) membrane as an actuator component in a microfluidic device. Polydimethylsiloxane membrane is a widely used structure in various applications in microfluidics. Most of the applications using PDMS membrane as actuators are pumps, valves, microlenses, and cell stimulators. In these applications, PDMS membranes are deflected to function by applied pressure. However, based on our literature survey, correlations between thickness, applied air pressure, and the deflection properties of replaceable PDMS membrane have not been theoretically and experimentally investigated yet. In this paper, we first conducted a simulation to analyze the relationship between deflection of the replaceable PDMS membrane and applied pressure. Then we verified the deflection of the PDMS membrane in different experimental conditions. Finally, we demonstrated that the PDMS membrane functioned as a valve actuator in a cell-capturing device as one application. We expect this study would work as an important reference for research investigations that use PDMS membrane as an actuator.

Effect of external stress on hydride reorientation in zirconium

Fracture wear of grinding wheels