Dean-flow sample Clean-up to Optimise and Extend the Operational Envelope of Biodetection Systems. : Final report for the Centre for Defence Enterprise Research Project

This CDE funded research project sought to establish the applicability of microfluidic devices employing 'Dean-flow', a second order flow effect, to the 'clean-up' of real-world aqueous suspension samples prior to their analysis for bio-threat agents. 'Clean-up' concerns the removal of environmental and man-made materials mixed with 'targets' in collected samples: such materials can interfere with subsequent sample processing and ultimately bio assays. Depending upon the collection modality, contaminants might include soil particles, naturally occurring biological entities or fragments thereof. Dean-flow performs clean-up by means of physical separation exploiting differential hydrodynamic drag forces acting upon target materials and contamination. The project involved the study and experimental evaluation of microfluidic Dean-flow devices in order to begin to characterise Dean-flow behaviour in this regime. Inter alia, this commenced development of a 'process sequence' (manufacturing protocol) to yield suitable, pressure-tolerant, microfluidic devices. Having established the process sequence, a significant number of tests were performed to evaluate separation of synthetic (for instance differently sized, polystyrene-latex, microbeads) and real (BG spores, yeast, soil samples) materials. Considerable effort was put into developing particle measurement skills and techniques using flow cytometry, fluorescence microscopy and dedicated particle counting equipmenti. The project was highly successful. All initial objectives were met, several (in particular minimum particle size) exceeded, and further experiments conducted. The TRL was raised from TRL3 to TRL4 and technique is viewed as having significant potential with further development and integration with other technologies of interest to dstl.