Integrating microelectromechanical systems with integrated circuits

From the very beginning, integration of microelectromechanical systems (MEMS) with integrated circuits (ICs) was a major attraction of silicon micromachining technology. Significant progress toward integrating MEMS with ICs technologies has been made over the last four decades. Many products have been introduced and the benefits of such integration have been demonstrated. One of the most attractive developments, during the period of time called the Optical Bubble, was the vertical MEMS-IC integration, pioneered by Transparent Networks. It enabled a short path to merging VLSI electronics with MEMS. This approach can be easily applied to capacitive sensors, such as pressure, acceleration, gyro, and vacuum sensors, as well as to a broad range of other products.     

Citrullination-Resistant LL-37 Is a Potent Antimicrobial Agent in the Inflammatory Environment High in Arginine Deiminase Activity

LL-37, the only member of the mammalian cathelicidin in humans, plays an essential role in innate immunity by killing pathogens and regulating the inflammatory response. However, at an inflammatory focus, arginine residues in LL-37 can be converted to citrulline via a reaction catalyzed by peptidyl-arginine deiminases (PAD2 and PAD4), which are expressed in neutrophils and are highly active during the formation of neutrophil extracellular traps (NETs). Citrullination impairs the bactericidal activity of LL-37 and abrogates its immunomodulatory functions. Therefore, we hypothesized that citrullination-resistant LL-37 variants would retain the functionality of the native peptide in the presence of PADs. To test this hypothesis, we synthetized LL-37 in which arginine residues were substituted by homoarginine (hArg-LL-37). Bactericidal activity of hArg-LL-37 was comparable with that of native LL-37, but neither treatment with PAD4 nor exposure to NETs affected the antibacterial and immunomodulatory activities of hArg-LL-37. Importantly, the susceptibilities of LL-37 and hArg-LL-37 to degradation by proteases did not significantly differ. Collectively, we demonstrated that citrullination-resistant hArg-LL-37 is an attractive lead compound for the generation of new agents to treat bacterial infections and other inflammatory diseases associated with enhanced PAD activity. Moreover, our results provide a proof-of-concept for synthesis of therapeutic peptides using homoarginine.     

Marvelous MEMS

Microelectromechanical systems (MEMS) are a foundation for a broad range of mechanical, chemical, optical, and biotech products (sensors, microstructures and actuators) fabricated as integrated circuits on (primarily) silicon wafers in a batch mode. Commercial MEMS products include pressure sensors, acceleration sensors, gyros, ink-jet nozzles, read-write head positioners in hard drives, and digital light processors (DLPs) in projectors and television sets. The first four decades of MEMS development created a US$8 billion market. During the next decade, the MEMS market is estimated to increase by US$32 billion. Based on the presented overview of emerging MEMS sensors and microstructures, such a magnitude of growth is definitely possible.     

Micromachines on the march

Miniature electromechanical sensors and actuators can be mass produced on silicon wafers much like ICs. They combine readily with signal-processing circuitry into powerful tools that measure, analyze, and control their environments. The authors describe the fabrication techniques, surface activity, atomic bonds, LIGA and SLIGA, and bury and destroy. The following applications are discussed: pressure sensors, medical equipment, industrial/consumer equipment, avionics, and mechanical applications