Microfluidic DNA extraction and quantification using a nanoporous membrane and flow rate analysis

A genomic DNA (gDNA) extraction and quantification system using flow rate analysis was designed and fabricated using a nanoporous membrane-embedded microfluidic system. A nanoporous aluminum oxide membrane was embedded in a microfluidic system that was fabricated using a PDMS/tape composite. To prove the concept of the system, 370nm nanoparticles were used and extracted on a membrane with 200nm pores. As nanoparticles collect on the membrane, the flow rate initially decreases linearly before switching to an exponential decrease. In a similar manner, a gDNA sample was flowed and trapped on the membrane and the measured flow rate change was used to evaluate the mass of gDNA on the membrane. After preliminary testing, gDNA of 6.25ng/(al, 12.5ng/ul, 18.75ng/|ul and 25ng/^l concentrations were extracted over 20nm pore sized membranes and a similar flow rate profile was observed. As the amount of gDNA trapped on the membrane increases, the pressure drop in the microfluidic system increases. Using the experimental data, one can develop an empirical formula for the mass of gDNA collected and the concentration of gDNA in the sample. From this empirical equation, it is possible to estimate the gDNA sample concentration from the measured flow rate change caused by an unknown sample. By integrating this system with a microfluidic gDNA sample preparation system, we not only extract gDNA, but also quantify the mass of gDNA collected, which allows for operators to end tests that will clearly be negative or allows operators to extend the extraction process until sufficient nucleic acid material is obtained.