AAAR 35th Annual Conference October 17 - October 21, 2016 Oregon Convention Center Portland, Oregon, USA
Abstract View
Droplet Microfluidics Detector for Bioaerosols
BRIAN DAMIT, Johns Hopkins University Applied Physics Laboratory
Abstract Number: 386 Working Group: Bioaerosols
Abstract Effective detection of bioaerosols is important in fields ranging from environmental health monitoring to biosurveillance. Current detectors are limited by slow response time and expensive consumption of reagents and these weaknesses have compelled the development of new technologies. In this work, a detector was developed which applies the principles of droplet microfluidics to bioaerosol detection. Droplet microfluidics is a subfield of microfluidics based on the creation of nanoliter/femtoliter droplets containing compartmentalized reagents and boasts enhanced assays and easy fluidic manipulations. The bioaerosol detector here functions by precisely focusing aerosols directly into these droplets, and thus harness the benefits offered by a droplet microfluidics platform.
A breadboard detector system, which consisted of an aerodynamic focusing lens, aerosol-focusing nozzle, custom microfluidic droplet chip, and fluorescence microscope, was constructed. Computational fluid dynamic simulations and Lagrangian particle tracking modeling were completed to identify the optimal conditions for aerosol focusing into the droplets. Preliminary experiments, wherein test PSL aerosols were deposited onto solid substrates, demonstrated sub 200-micron spot diameters for aerodynamic sizes of 2-5 micron. After obtaining fine aerosol focusing, collection of aerosols in the droplets was achieved by positioning the chip below the nozzle, forming a pinned air-liquid interface at the chip surface, and then focusing test aerosols into that interface. Real-time inspection via microscopy confirmed aerosol capture at the interface.
Finally, to show proof-of-concept, a simple droplet propidium iodide (PI) assay was performed: the system was able to distinguish between E. coli and non-biological aerosols collected in a microfluidic droplet within 20 s of PI incubation. Overall, this work successfully established the technique of direct collection of aerosols into a convenient droplet microfluidic platform for the purpose of rapid bioaerosol detection.