Multi-wall vertically aligned carbon nanotubes (VACNTs) are nearly ideal absorbers due to their exceptionally low reflectance over a broad wavelength range. Integrating VACNTs as bolometer absorbers, however, can be difficult due to their high growth temperature and fragile nature. Despite these challenges, we have microfabricated many different types of VACNT bolometers, ranging from cryogenic optical power primary standards to room temperature satellite-based solar irradiance monitors and broadband infrared microbolometers. Advantages our VACNT bolometers provide over the bolometers they replace vary by application, but can be reduced size and time constant, increased absorption, and/or microfabrication instead of hand assembly. Depending on the application and operating conditions, our VACNT bolometers are designed with a variety of thermistors and weak thermal links. The thermistors used include commercial surface mount chips, superconducting transition-edge sensors, and vanadium oxide (VOx). Weak thermal links include silicon nitride (SiNx) membranes, Si bridges, and laser-cut polyimide. We summarize a wide variety of microfabricated bolometers with VACNT absorbers that measure optical power levels spanning over seven orders of magnitude.
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We have designed and fabricated a microfluidic system made of glass and polydimethylsiloxane. A micro-magnetometer has been integrated to the system. This sensor is made of a giant magnetoimpedance wire known to have very high magnetic sensitivity at room temperature. A liquid-liquid segmented multiphase flow was generated in the channel using a Y-shaped inlet junction. The dispersed phase plugs contained superparamagnetic iron oxide (20 nm) nanoparticles at a molar concentration of 230 mmol/l. We have shown both theoretically and experimentally that in-flow detection of these nanoparticles is performed by the microsystem for concentration as small as 5.47 Â 10 À9 mol. These performances show that it is conceivable to use this system for ex-vivo analysis of blood samples where superparamagnetic iron oxide nanoparticles, initially used as magnetic contrast agents, could be functionalized for biomarkers fishing. It opens new perspectives in the context of personalized medicine.
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