Reliability aspects of microsensors and micromechatronic actuators for automotive applications

In modern cars microsensors and micromechatronic actuators play an essential and still increasingly important role as the interface between the vehicle with its complex functions of motor management, chassis systems, safety as well as comfort and convenience on the one hand and the respective electronic control units on the other hand. They have to fulfill their task in a harsh environment over the entire lifetime of an automobile. Therefore reliability aspects have moved more and more into the focus of engineering and research activities in microsystem technology. A methodical procedure is described that allows reliability issues to be approached efficiently. The implementation of the methodology is illustrated with real-life examples of reliability aspects of hot film mass air flow sensors, inertial sensors as well as piezoelectric actuators.     

Surface roughness investigation of semi-conductor wafers

Conventionally, surface roughness is predominantly determined through the use of stylus instruments. However, there are certain limitations involved in the method, particularly when a test specimen, such as a silicon wafer, has a smooth mirror-like surface. Hence, it is necessary to explore alternative non-contact techniques. Light scattering has recently been gaining popularity as an optical technique to provide prompt and precise inspection of surface roughness. In this paper, the total integrated scattering (TIS) model is modified to retrieve parameters on surface micro-topography through light scattering. The applicability of the proposed modified TIS model is studied and compared with an atomic force microscope. Experimental results obtained show that the proposed technique is highly accurate for measuring surface roughness in the nanometer range.     

A study of electrostatic spring softening for dual-axis micromirror

Electrostatic spring softening is an important characteristic of electrostatically actuated dual-axis micromirror, since it lowers the resonant frequencies. This paper presents an approach based on approximating the electrostatic forces by the first-order Taylor's series expansion to investigate this characteristic. The dual-axis micromirror studied in this paper has three motion modes, two torsional (about x- and y-axis, respectively) and one translational (about z-axis). The stiffnesses of all these modes are softened by a DC bias voltage applied to the mirror plate. The resonant frequencies are lowered with the increment of the bias voltage. The relationship of the bias voltage and the resonant frequencies of all the motion modes is derived. The analytical results show that the resonant frequency curves are affected by the capacitor geometries, i.e. the gap between the mirror plate and the electrodes and the electrodes size. The lowering curves drop slowly when the bias voltage is small. While for large bias voltage, the lowering curves drop rapidly. The experiment results are consistent with those obtained by the analytical approach.     

A new interpretation of quantum mechanics and its consequences in epistemology

A rather recent interpretation of quantum mechanics, known under the various names of consistent histories, decohering histories, or logical interpretation, has brought interpretation into a standard deductive theory and is now investigated in many places. A key difference with the Copenhagen interpretation is the status of classical physics, now derived completely from quantum principles in both its dynamical and logical aspects. After describing briefly this new interpretation in its essentials, leaving aside technical details, it is shown how its consequences in epistemology differ drastically from the familiar outcomes of the Copenhagen interpretation, leading in particular to a well-defined theory of knowledge. Some more speculative philosophical consequences associated with the unsolved problem of actuality are also mentioned.     

Effects of chemical, physical, and technological processes on the nature of food allergens

A review is presented of studies of different processing techniques and their effect on the allergenicity and antigenicity of certain allergenic foods. An overview of investigated technologies is given with regard to their impact on the protein structure and their potential application in the production of hypoallergenic foods. The use of physical processes (such as heating, high pressure, microparticulation, ultrafiltration, and irradiation), chemical processes (such as proteolysis, fermentation, and refining by extraction), and biotechnological approaches, as well as the effects of these processes on individual allergenic foods, are included. Additionally, the implications of food processing for food allergen analysis with respect to food safety assessment and industrial quality control are briefly discussed.     

Formation of spanning water networks on protein surfaces via 2D percolation transition

The formation of spanning hydrogen-bonded water networks on protein surfaces by a percolation transition is closely connected with the onset of their biological activity. To analyze the structure of the hydration water at this important threshold, we performed the first computer simulation study of the percolation transition of water in a model protein powder and on the surface of a single protein molecule. The formation of an infinite water network in the protein powder occurs as a 2D percolation transition at a critical hydration level, which is close to the values observed experimentally. The formation of a spanning 2D water network on a single rigid protein molecule can be described by adapting the cluster analysis of conventional percolation studies to the characterization of the connectivity of the hydration water on the surface of finite objects. Strong fluctuations of the surface water network are observed close to the percolation threshold. Our simulations also furnish a microscopic picture for understanding the specific values of the experimentally observed hydration levels, where different steps of increasing mobility in the hydrated powder are observed.