This paper reports on the development of a hand-held device for on-site detection of
organophosphonate nerve agent degradation products. This field-deployable analyzer relies on
efficient microchip electrophoresis separation of alkyl methylphosphonic acids and their sensitive
contactless conductivity detection. Miniaturized, low-powered design is coupled with promising
analytical performance for separating the breakdown products of chemical warfare agents such as
Soman, Sarin and VX . The detector has a detection limit of about 10 μg/mL and has a good linear
response in the range 10-300 μg/mL concentration range. Applicability to environmental samples is
demonstrated .The new hand-held analyzer offers great promise for converting conventional ion
chromatography or capillary electrophoresis sophisticated systems into a portable forensic laboratory
for faster, simpler and more reliable on-site screening.
Microbubbles have been used as ultrasound contrast agents in medical applications such as imaging, and also for
drug/gene delivery, target destruction and so on. Microbubbles are normally made by sonication techniques and the
resulting size distribution is very large. Microfluidics provides an alternative way of microbubble fabrication due to
recent advances in microfabrication and microfluidics development. The current techniques are capable of making
bubbles with a size of several micrometers. However, the throughput for such a size range is very limited. In this study, a
new microfluidic bubble generation chip was developed, which incorporates a T-junction PDMS microchannel network
with an inserted glass capillary. The flow rate of liquid, gas pressure and the inserted capillary inner diameter are crucial
for control of the bubble size. A series of capillaries with different inner diameters have been used. With co-flow
focusing liquids and a fine-drawn glass capillary, bubble size could be decreased and bubbles with a size of 13 μm in
diameter were generated reliably after the optimizing of liquid flow rate and gas pressure. It was found that a 5 μm
capillary inserted microchip produced 11 μm diameter bubbles with a cross-flow rupturing method.
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