Eddy Current Sensor System for Tilting Independent In-Process Measurement of Magnetic Anisotropy

Modern production equipment is based on the results of quality control as well as process parameters. The magnetic anisotropy of materials is closely connected to internal mechanical stress by the Villari effect, and also to hardening effects due to plastic deformations, and could therefore provide an interesting basis for process control. Nevertheless, the analysis of anisotropic properties is extremely sensitive to sensor and workpiece misalignments, such as tilting. In this work, a novel eddy current sensor system is introduced, performing a non-contact measurement of the magnetic anisotropy of a workpiece and realizing a separation and correction of tilting effects. The measurement principle is demonstrated with the example of two samples with different magnetic anisotropy values induced by cold forming. Both samples are analyzed under different tilt angles between the sensor axis and the surface of the workpiece. In this work, digital signal processing is demonstrated on the acquired raw data in order to differentiate the effects of tilt and of anisotropy, with the use of preliminary results as an example of two prepared samples.

Biofilms deform soft surfaces and disrupt epithelia

During chronic infections and in microbiota, bacteria predominantly colonize their hosts as multicellular structures called biofilms. A common assumption is that biofilms exclusively interact with their hosts biochemically. However, the contributions of mechanics, while being central to the process of biofilm formation, have been overlooked as a factor influencing host physiology. Specifically, how biofilms form on soft, tissue-like materials remains unknown. Here, we show that biofilms of the pathogens Vibrio cholerae and Pseudomonas aeruginosa can induce large deformations of soft synthetic hydrogels. Biofilms buildup internal mechanical stress as single cells grow within the elastic matrix. By combining mechanical measurements and mutations in matrix components, we found that biofilms deform by buckling, and that adhesion transmits these forces to their substrates. Finally, we demonstrate that V. cholerae biofilms can generate sufficient mechanical stress to deform and even disrupt soft epithelial cell monolayers, suggesting a mechanical mode of infection.

Исследование плазменных колебаний в стеклообразных диэлектриках методом полного внешнего отражения рентгеновских лучей

Glass-like dielectrics are studied by methods of plasmon dispersion and asymmetry of the number of localized electrons in the zone of formation of the total external reflection of x-rays and the excitation of plasma vibrations. Defined by the internal mechanical stress and the associated polarization of the investigated dielectrics. The absence of internal mechanical stress in a single crystal of lithium fluoride was found out, and the observed polarization is caused by a large macroscopic dipole moment in this single crystal

Analysis on Effect of Birefringence in an Image Forming Lens of a Laser Scan Unit on Optical Characteristics

In most cases of molding process with glass or optical polymer, it is inevitable to avoid birefringence arisen due to residual internal mechanical stress in a molded material. Even though distribution of the residual stress can be annealed by slow cooling, it has a disadvantage on shape accuracy and manufacturing time. This study mainly analyzes variation in optical performance considering optical phase delay and difference in orientation angles between two principal optical axes due to birefringence. And the simulated optical characteristics are compared with experimental spot profiles from the image forming lens of a laser scan unit, which has specific degree of generation of birefringence. Through this study, we are going to clarify birefringence condition of the image forming lens for a LSU (Laser Scan Unit) to induce degradation in optical performance.

Advanced 3D Packaging of Chips and Materials Integrity: Stress-Induced Effects and Mechanical Properties of New Ultra Low-k Dielectrics for On-Chip Interconnect Stacks

Managing the emerging internal mechanical stress in chips particularly if they are 3D-tscked is a key task to maintain performance and reliability of microelectronic products. Hence, a strong need of a physics-based simulation methodology/flow emerges. This physics-based simulation, however, requires materials parameters with high accuracy. A full-chip analysis can then be performed, balancing the need for local resolution and computing time. Therefore, effective composite-type materials data for several regions of interest are needed. Advanced techniques to measure FEA-and design-relevant properties such as local and effective Youngs modulus and effective CTE values were developed and described in this paper. These data show a clear orientation dependence, caused by the chip design.

Ge/Si Quantum Dots Superlattices Grown at Different Temperatures and Characterized by Raman Spectroscopy and Capacitance Measurements

Ge/Si heterostructures with Ge self-assembled quantum dots (SAQDs) grown at various temperatures by molecular beam epitaxy were investigated using resonant Raman spectroscopy and capacitance measurements. The occurrence of quantum confinement effects was confirmed by both techniques. For the structures grown at low temperatures (300−400°C), the SAQDs optical phonon wavenumbers decrease as the Raman excitation energy is increased; this is an evidence of the scattering sensitivity to the size of the SAQDs and to the inhomogeneity in their sizes. However, the opposite behavior is observed for the SAQDs grown at higher temperatures, as a consequence of the competition between the phonon localization and internal mechanical stress effects. TheE1electronic transition of the Ge in the SAQDs was found to be shifted towards higher energies as compared to bulk Ge, due to biaxial compressive stress and to the electronic confinement effect present in the structures. The intermixing of Si atoms in the quantum dots was found to be much more significant for the sample grown at higher temperatures. The capacitance measurements, besides confirming the existence of the dots in these structures, showed that the deepest Ge layers lose their 0D signature as the growth temperature increases.

VHF Plasma Deposition: A Comparative Overview

ABSTRACTThe use of plasma excitation frequencies f in the VHF band (30–300 MHz), and particularly of f=70 MHz, for the high-rate deposition of amorphous hydrogenated silicon (a-Si:H) is described. Deposition rates, using monosilane (SiH4) as source gas, are thereby increased roughly five fold to over 10 Å/s as compared with the conventional case of RF plasma enhanced chemical vapour deposition with f=13.56 MHz. This may possibly be attributed to an enhancement in the high-energy tail of the electron energy distribution function (EEDF) of the plasma. Thereby, no noticeable deterioration in film properties is found.Characteristics of VHF-deposited a-Si:H films are extensively reported, including properties like microstructure, hydrogen effusion behaviour and its low internal mechanical stress. High quality hydrogenated microcrystalline silicon (μc-Si:H) can be deposited at low substrate temperature and low plasma power densities thanks to VHF glow discharge. This can be linked to a reduction in sheath potential and to the energy of the ions arriving at the growing surface. Thereafter, use of VHF plasma in applications such as 100 μm thick a-Si:H layer for particle detectors and powder-free deposition of solar cells with efficiencies over 8% are reported.