Microdroplet-based microfluidic devices are emerging as powerful tools for a wide range of biochemical screenings and analyses. Monodispersed aqueous microdroplets from picoliters to nanoliters in volume are generated inside microfluidic channels within an immiscible oil phase. This results in the formation of emulsions which can contain various reagents for chemical reactions and can be considered as discrete bioreactors. In this paper an integrated microfluidic platform for the synthesis, screening and sorting of libraries of an organophosphate degrading enzyme is presented. The variants of the selected enzyme are synthesized from a DNA source using in-vitro transcription and translation method. The synthesis occurs inside water-in-oil emulsion droplets, acting as bioreactors. Through a fluorescence based detection system, only the most efficient enzymes are selected. All the necessary steps from the enzyme synthesis to selection of the best genes (producing the highest enzyme activity) are thus integrated inside a single and unique device. In the second part of the paper, an innovative design of the microfluidic platform is presented, integrating an electronic prototyping board for ensuring the communication between the various components of the platform (camera, syringe pumps and high voltage power supply), resulting in a future handheld, user-friendly, fully automated device for enzyme synthesis, screening and selection. An overview on the capabilities as well as future perspectives of this new microfluidic platform is provided.
Capillary Electrophoresis (CE) is a separation technique that can be used as a sample pre-treatment step in
chemical analysis. When coupled with a detection technique, identification of chemical species can be performed
on the basis of the elution signals. However, the sensor signals are often complicated by high signal noise,
varying baseline and overlapping peaks. There is thus a need for a signal processing technique capable of
robustly detecting peaks in acquired sensor data. Here, we report on an algorithm that utilises the Continuous
Wavelet Transform (CWT) for the detection of analyte peaks.
The algorithm that has been developed makes use of a wavelet equal to the first derivative of a Gaussian function
and has been successfully applied to data obtained from a CCD sensor fabricated on a polymer microfluidic
separation chip. The algorithm operates by taking the CWT of the sensor response. It then analyses patterns in
the local maximum and minimum points evident across scales in the CWT coefficients to find the peaks in the
time series data. The performance of two versions of the algorithm have been compared for synthetic data sets
each with known baseline, peaks and noise. The improved algorithm has been shown to successfully find peaks
with a high sensitivity and low False Discovery Rate within a range of sensitivities.
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.