A fully integrated microfluidic system was developed and incorporates an EC-MWCNT (electrochemical multiwalled
carbon nanotube) sensor for the detection of bacteria. Sample metering, reagent metering and delivery was
implemented with microvalves and pumps embedded inside the microfluidic system. The nucleic acid extraction was
performed using microchannels controlled using automated platforms and a disposable microfluidic silica cartridge.
The target samples were flowed and hybridized with probe ssDNA (single strand DNA) across the MWCNT-EC
sensor (built on a silicon chip), which was embedded in a microfluidic cell. The 9-pad sensor was scanned before
and after hybridization to measure the quantity of RNA (Ribonucleic acid) bound to the array surface. A rapid and
accurate sample-in answer-out nucleic acid system was realized with automated volume metering, microfluidic
sample preparation, and integrated nano-biosensors.
A DNA extraction system was designed and fabricated using an AOM (aluminum oxide membrane) with 200 nm pores and PDMS microfluidic channels. The membrane was patterned using soft lithography techniques and SU-8 photolithography on the membrane. After making the pattern with SU-8, the AOM was observed using an SEM (scanning electro microscope) to verify the AOM structure was not damaged. From the SEM images, the AOM structure was not different after modification with SU-8. To complete the system, a PDMS mold for the microfluidic channels was made by soft lithography. Using the SU-8 mold, PDMS microchannels were cast using PDMS with a low polymer to
curing agent ratio to provide adhesion between the patterned membrane and microfluidic channel. Then, the patterned membrane was sandwiched between PDMS microfluidic channels in a parallel format. The completed system was tested with 10ug of Lambda DNA mixed with the fluorescent dye SYBR Green I. Following DNA extraction, the surface of each well was examined with fluorescence microscopy while embedded in the microfluidic system. Extracted and immobilized DNA on the AOM was observed in almost every separation well. This microsystem, referred to as a membrane-on-a-chip, has potential applications in high-throughput DNA extraction and analysis, with the possibility of
being integrated into polymer-based microfluidic systems.