As part of a ​Bill and Melinda Gates Foundation grant, we (Northwestern Global Health Foundation)  co-developed a PCR-based diagnostic platform for use in both the developed and developing world.  Our responsibility was to develop overall test cartridge architecture to assure very pure nucleic acid is delivered to the PCR chamber.

The test initially takes a sample (e.g. blood, thinned sputum, universal transfer media), lyses the cells, picks up the nucleic acids on treated magnetic beads then moves them through a series of washes and through an oil layer.  The oil layer displaces the water so that contaminent carry over is minimized.   Our project was to take the immiscible phase technology (oil-water) and design a cartridge architecture that allows filling, mixing and bead movement thoughout the cartridge.  Inital prototypes were made using layered laser cut plastics and adhesive to investigate chamber shapes and filling approaches.  The next stage of design further refined chamber geometries and mixing methods using specially coated SLA parts and vapor polished polycarbonate parts.  The final mixing approach selected was sonication with an external horn transmitting ultrasonic energy through the cartrdige and into the fluid. When the final geometery was finally extablished, injection molds were made.  The parts continue to be used for assay development.  The design also served as the starting point for a production version of the cartridge where on-board reagents were incorporated.  The completed system is expected to be in field trials in 2017.

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This project was done at Northwestern University in partnership with Quidel Corporation with funding from the Northwestern Global Health Foundation.