Low-cost polymer microfluidic device for on-chip extraction of bacterial DNA

A polymer microfluidic device for on-chip extraction of bacterial DNA has been developed for molecular diagnostics. In order to manufacture a low-cost, disposable microchip, micropillar arrays of high surface-to-volume ratio (0.152 μm−1) were constructed on polymethyl methacrylate (PMMA) by hot embossing with an electroformed Ni mold, and their surface was modified with SiO2 and an organosilane compound in subsequent steps. To seal open microchannels, the organosilane layer on top plane of the micropillars was selectively removed through photocatalytic oxidation via TiO2/UV treatment at room temperature. As a result, the underlying SiO2 surface was exposed without deteriorating the organosilane layer coated on lateral surface of the micropillars that could serve as bacterial cell adhesion moiety. Afterwards, a plasma-treated PDMS substrate was bonded to the exposed SiO2 surface, completing the device fabrication. To optimize manufacturing throughput and process integration, the whole fabrication process was performed at 6 inch wafer-level including polymer imprinting, organosilane coating, and bonding. Preparation of bacterial DNA was carried out with the fabricated PDMS/PMMA chip according to the following procedure: bacterial cell capture, washing, in situ lysis, and DNA elution. The polymer-based microchip presented here demonstrated similar performance to Glass/Si chip in terms of bacterial cell capture efficiency and polymerase chain reaction (PCR) compatibility.