MEMS Accelerometers

Micro-electro-mechanical system (MEMS) devices are widely used for inertia, pressure, and ultrasound sensing applications. Research on integrated MEMS technology has undergone extensive development driven by the requirements of a compact footprint, low cost, and increased functionality. Accelerometers are among the most widely used sensors implemented in MEMS technology. MEMS accelerometers are showing a growing presence in almost all industries ranging from automotive to medical. A traditional MEMS accelerometer employs a proof mass suspended to springs, which displaces in response to an external acceleration. A single proof mass can be used for one- or multi-axis sensing. A variety of transduction mechanisms have been used to detect the displacement. They include capacitive, piezoelectric, thermal, tunneling, and optical mechanisms. Capacitive accelerometers are widely used due to their DC measurement interface, thermal stability, reliability, and low cost. However, they are sensitive to electromagnetic field interferences and have poor performance for high-end applications (e.g., precise attitude control for the satellite). Over the past three decades, steady progress has been made in the area of optical accelerometers for high-performance and high-sensitivity applications but several challenges are still to be tackled by researchers and engineers to fully realize opto-mechanical accelerometers, such as chip-scale integration, scaling, low bandwidth, etc

EUROSENSORS XVII : book of abstracts

Fundação Calouste Gulbenkien (FCG).Fundação para a Ciência e a Tecnologia (FCT)

The Conference on High Temperature Electronics

The status of and directions for high temperature electronics research and development were evaluated. Major objectives were to (1) identify common user needs; (2) put into perspective the directions for future work; and (3) address the problem of bringing to practical fruition the results of these efforts. More than half of the presentations dealt with materials and devices, rather than circuits and systems. Conference session titles and an example of a paper presented in each session are (1) User requirements: High temperature electronics applications in space explorations; (2) Devices: Passive components for high temperature operation; (3) Circuits and systems: Process characteristics and design methods for a 300 degree QUAD or AMP; and (4) Packaging: Presently available energy supply for high temperature environment

Experimental Facilities Division progress report 1996--97

This progress report summarizes the activities of the Experimental Facilities Division (XFD) in support of the users of the Advanced Photon Source (APS), primarily focusing on the past year of operations. In September 1996, the APS began operations as a national user facility serving the US community of x-ray researchers from private industry, academic institutions, and other research organizations. The start of operations was about three months ahead of the baseline date established in 1988. This report is divided into the following sections: (1) overview; (2) user operations; (3) user administration and technical support; (4) R and D in support of view operations; (5) collaborative research; and (6) long-term strategic plans for XFD

NASA Tech Briefs, June 1993

Topics include: Imaging Technology: Electronic Components and Circuits; Electronic Systems; Physical Sciences; Materials; Computer Programs; Mechanics; Machinery; Fabrication Technology; Mathematics and Information Sciences; Life Sciences

Structure of Cross-Bridges in Vertebrate Skeletal Muscle Activated by Photolysis of Caged Ca2+

In order to understand the contraction mechanism in vertebrate skeletal muscle, one must correlate the structural and mechanical details of the cross-bridge cycle on the millisecond time scale. Using electron microscopy, I investigated the structure of cross-bridges in fibers activated by photolysis of caged ca2+ and then ultra­rapidly frozen and freeze substituted with tannic acid and OsO4. Sections from relaxed fibers show helical tracks, presumed to be rnyosin heads, on the thick filament surface. Optical diffraction patterns show strong meridional spots and layer lines up to the 6th order of the 429 Å repeat, indicating preservation and resolution of periodic structures smaller than 100 Å . Following photo-release of ca2+, the myosin 1/429 Å-1 layer line becomes less intense, and higher orders disappear, both with a time course which precedes the rise in tension. Å 1/360 Å-1 layer line appears early in contraction ( 12-15 ms) and becomes stronger at later times. The intensity of the 1/143 Å_-1 meridional spot decreases initially and then increases to greater than its value in relaxed fibers, while it broadens six-fold laterally. The 1/430 Å-1 meridional spot is present during contraction but markedly weakened. The 1/215 Å-1 meridional spot is weak or absent. These results are consistent with time resolved X-ray diffraction data on the periodic structures within the fiber. The intensification of the 1/360 Å-1 layer line, with a concomitant decrease in the intensity of the 1/429 Å-1 layer line, supports the view that at least some cross­bridges decorate the thin filament during contraction with an act in based set of periodicities, but not to the same degree as is seen in rigor. The lateral spread of the 1/ 143 Å-1 meridional spot indicates a disorder of axial coherence among thick filaments during tension development. In sections along the (1,1) plane of activated fibers, the individual cross-bridges have a wide range of shapes and angles, perpendicular to the fiber axis or pointing toward or away from the Z-line. Fibers frozen at 12-15 ms, 30-35 ms, and 210-220 ms after photolysis all show surprisingly similar cross-bridges. Thus, a highly variable distribution of cross-bridge shapes and angles is established early in contraction

Cumulative index to NASA Tech Briefs, 1986-1990, volumes 10-14

Tech Briefs are short announcements of new technology derived from the R&D activities of the National Aeronautics and Space Administration. These briefs emphasize information considered likely to be transferrable across industrial, regional, or disciplinary lines and are issued to encourage commercial application. This cumulative index of Tech Briefs contains abstracts and four indexes (subject, personal author, originating center, and Tech Brief number) and covers the period 1986 to 1990. The abstract section is organized by the following subject categories: electronic components and circuits, electronic systems, physical sciences, materials, computer programs, life sciences, mechanics, machinery, fabrication technology, and mathematics and information sciences