Segmentation of the fascia lata and reproducible quantification of intermuscular adipose tissue (IMAT) of the thigh

Magnetic Resonance Materials in Physics, Biology and Medicine - To develop a precise semi-automated segmentation of the fascia lata (FL) of the thigh to quantify IMAT volume in T1w MR images and...     

Automated immunomagnetic processing and separation of Legionella pneumophila with manual detection by sandwich ELISA and PCR amplification of the ompS gene

The culture-independent and automated detection of bacteria in the environment is a scientific and technological challenge. For detection alone, a number of sensitive methods are known (e.g., PCR, enzyme-linked immunosorbent assay [ELISA], fluorescent in situ hybridization) but a major problem remaining is the enrichment and separation of the bacteria that usually occur at low concentrations. Here, we present an automated capturing and separation system, which can easily be combined with one of the sensitive detection techniques. We have developed a method for enrichment and detection of Legionella pneumophila in liquid media. Concentrated microorganisms were either detected by PCR or by sandwich ELISA. The limit of detection with the immunological assay was about 750 bacteria. Using PCR, the equivalent of about 2000 genomes could be detected. The assays were then transferred to a laboratory prototype for automated processing. It was possible to automatically enrich L. pneumophila by immunomagnetic separation (IMS), and again, the bacteria were detected by sandwich ELISA and PCR amplification of the ompS gene. As a novel aspect, ompS gene was used for the first time as a target for the detection of L. pneumophila on magnetic beads. The aim of this work was to develop an automated procedure and a device for IMS of bacteria. With Legionella as a model organism, we could show that such a novel fully automated system can be an alternative to time-consuming conventional cultivation methods for detecting bacteria or other microorganisms.     

The influence of plasma power on the temperature-dependant conductivity and on the wet chemical etch rate of sputter-deposited alumina thin films

Aluminum oxide (Al₂O₃) thin films are synthesized by reactive d.c. magnetron sputter deposition on silicon substrates. The impact of varying plasma power P_p (i.e. 400 to 1000 W) and of thin film temperatures T up to 540 °C on the electrical performance are evaluated, as these dielectric layers with a thickness of 450 nm are targeted as potential candidates for high temperature sensor applications. From 150 °C to 500 °C, the current-voltage measurements show a leakage current behavior according to the Poole-Frenkel electron emission with an activation energy of 1.16 eV. At T > 500 °C, the conductivity increases above average, in respect to the extrapolated Poole-Frenkel behavior at T < 500 °C, most probably due to the migration of charged ions, such as Ar⁺, incorporated into the film during deposition. Basically, samples synthesized at higher plasma levels show an enhanced electrical insulation behavior. This result is supported by measurements applying optical ellipsometry as well as by the determination of the wet chemical etching behavior in phosphoric-based acid at different bath temperatures. At higher plasma power, the refractive index shows a slight tendency to increase, staying, however, below the value of single-crystalline Al₂O₃. In contrast, the etch rate decreases by a factor of 1.5 at samples deposited at 1000 W when lowering the temperature of the etchant from 90 °C to 60 °C. These results indicate an enhanced film density at higher P_p values as the microstructure of the Al₂O₃ films is X-ray amorphous independent of plasma power and post-deposition annealing temperatures up to 650 °C.     

MEMS-based microthruster with integrated platinum thin film resistance temperature detector (RTD), heater meander and thermal insulation for operation up to 1,000°C

We have fabricated microthruster chip pairs—one chip with microthruster structures such as injection capillaries, combustion chamber and converging/diverging nozzle machined using the deep reactive ion etching process, the other chip with sputtered platinum (Pt) thin film devices such as resistance temperature detectors (RTDs) and a heater. To our knowledge, this is the first microelectromechanical systems-based microthruster with fully integrated temperature sensors. The effects of anneal up to 1,050°C on the surface morphology of Pt thin films with varied geometry as well as with/without PECVD-SiO₂ coating were investigated in air and N₂ and results will also be presented. It was observed that by reducing the lateral scale of thin films the morphology change can be suppressed and their adhesion on the substrate can be enhanced. Chemical analysis with X-ray photoelectron spectroscopy showed that no diffusion took place between neighboring layers during annealing up to 1?h at 1,050°C in air. Electrical characterization of sensors was carried out between room temperature and 1,000°C with a ramp of ±5?Kmin^?1 in air and N₂. In N₂, the temperature-resistance characteristics of sensors had stabilized to a large extent after the first heating. After stabilization the sensors underwent up to eight further temperature cycles. The maximum drift of the sensor signal was observed for temperatures above 950°C and was less than 8.5?K in N₂. To reduce the loss of combustion heat, chip material around microthruster structures was partially removed with laser ablation. The effects of thermal insulation were investigated with microthruster chip pairs which were clamped together mechanically. The heater was operated with up to 20?W and the temperature distribution in the chip pairs with/without thermal insulation was monitored with seven integrated RTDs. The experiments showed that a thermal insulation allows the maximum temperature as well as the temperature gradient within the microthruster chip pairs to be increased.     

Improved surface-micromachined hinges for fold-out structures

We describe a new surface-micromachined polysilicon micromechanical hinge that is designed for “foldout” surface-micromachined elements. The new hinge shows reduced wobble and enhanced accuracy as compared to previous foldout hinge designs. Features of the new hinge, which is built using only two structural layers of polycrystalline silicon, are two sets of cantilevers that are fixed to opposing hinge flanges. These cantilevers overlay an axle and thereby allow rotation while holding the rotating part to the support member. A precise locking mechanism for 90° out-of-plane rotation makes this hinge design especially suitable for applications to fixed-position vertical-foldout micromirrors. Measurements on such mirrors have confirmed predicted high precision in vertical locking. The new hinge has also permitted the construction of a mirror on a movable carriage that has been driven in a one-dimensional (1-D) sliding motion more than 100 μm by on-chip microvibromotors