Dangerous materials present in factories and military combat locations, can cause negative effects to the human body and can be life threatening. Due to this, a portable, easily maintained, and robust sensor is required to detect CWA’s, TIC’s, and TIM’s. We present a method to grow MOFs on quartz crystal microbalances (QCM’s) for sensitive, selective detection of CWA’s. Our next step is to test the sensitivity and selectivity of the MOF to dimethyl methylphosphonate (DMMP) when under varying environmental conditions.
Gas Chromatography (GC) is routinely used in the laboratory to temporally separate chemical mixtures into their constituent components for improved chemical identification. This paper will provide a overview of more than twenty years of development of one-dimensional field-portable micro GC systems, highlighting key experimental results that illustrate how a reduction in false alarm rate (FAR) is achieved in real-world environments. Significantly, we will also present recent results on a micro two-dimensional GC (micro GCxGC) technology. This ultra-small system consists of microfabricated columns, NanoElectroMechanical System (NEMS) cantilever resonators for detection, and a valve-based stop-flow modulator. The separation of a 29-component polar mixture in less than 7 seconds is demonstrated along with peak widths in the second dimension ranging from 10-60 ms. For this system, a peak capacity of just over 300 was calculated for separation in about 6 s. This work has important implications for field detection, to drastically reduce FAR and significantly improve chemical selectivity and identification. This separation performance was demonstrated with the NEMS resonator and bench scale FID. But other detectors, suitably fast and sensitive can work as well. Recent research has shown that the identification power of GCxGC-FID can match that of GC-MS. This result indicates a path to improved size, weight, power, and performance in micro GCxGC systems outfitted with relatively non-specific, lightweight detectors. We will briefly discuss the performance of possible options, such as the pulsed discharge helium ionization detector (PDHID) and miniature correlation ion mobility spectrometer (mini-CIMS).
We are developing a highly miniaturized trapped ion clock to probe the 12.6 GHz hyperfine transition in the
171Yb+ ion. The clock development is being funded by the Integrated Micro Primary Atomic Clock
Technology (IMPACT) program from DARPA where the stated goals are to develop a clock that consumes
50 mW of power, has a size of 5 cm3, and has a long-term frequency stability of 10-14 at one month. One of
the significant challenges will be to develop miniature single-frequency lasers at 369 nm and 935 nm and the
optical systems to deliver light to the ions and to collect ion fluorescence on a detector.
This paper describes results from using a microcombustor to create two hydrocarbon gas sensors: one utilizing calorimetry and the other a flame ionization detector (FID) mechanism. The microcombustor consists of a catalytic film deposited on the surface of a microhotplate. This micromachined design has low heat capacity and thermal conductivity, making it ideal for heating catalysts placed on its surface. The catalytic materials provide a natural surface-based method for flame ignition and stabilization and are deposited using a micropen system, which allows precise and repeatable placement of the materials. The catalytic nature of the microcombustor design expands the limits of flammability (LoF) as compared with conventional diffusion flames; an unoptimized LoF of 1-32% for natural gas in air was demonstrated with the microcombustor, whereas conventionally 4-16% is observed. The LoF for hydrogen, methane, propane and ethane are likewise expanded. Expanded LoF permit the use of this technology in applications needing reduced temperatures, lean fuel/air mixes, or low gas flows. By coupling electrodes and an electrometer circuit with the microcombustor, the first ever demonstration of a microFID utilizing premixed fuel and a catalytically-stabilized flame has been performed; the detection of 1.2-2.9 % of ethane in a hydrogen/air mix is shown.
This paper discusses the fundamental technical challenges and solutions in converting still images from film through the digital domain to video. These include tone scale colorimetry quantization and resolution. The digital signal processing for a particular implementation of a slide-to-video transfer unit which employs a single CCD sensor is described. 2.
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