Shunting microfluidic PCR device for rapid bacterial detection

Polymerase chain reaction (PCR) is commonly used for the analysis of nucleic acids in a variety of applications including clinical. There is, however, a need for a low cost portable PCR device that allows rapid identification of pathogenic bacteria. We report a shunting PCR microfluidic device comprising: polycarbonate microfluidic PCR chip; shunting thermal cycler and fluorescence detector. The microfluidic PCR chip - fabricated using micro milling and thermal fusion bonding for sealing of the cover - was shunted between three double side temperature zones for thermal cycling. Rapid amplification was observed with heating and cooling rates of 1.8 degrees C/s and 2 degrees C/s respectively. Lock-in photodetector for fluorescence detection of the microfluidic PCR chip achieved at 95% confidence an LOD of 75pM FITC and 0.7 ng mu l(-1) of dsDNA using a QuantiFluor assay kit. The device was validated using universal primers - based on chromosomal DNA extracted from non-pathogenic K-12 subtype of Escherichia coil (E. coli) - for amplification of fragments of 250, 552 and 1500 bp. PCR amplification was demonstrated, with annealing temperatures ranging between 54 degrees C and 68 degrees C, and confirmed using gel electrophoresis. The developed shunting PCR microfluidic device will allow for low cost and portable nucleic acid amplification for the detection of infectious diseases.