(A) disposable microfluidic chip for DNA sample preparation of nucleic acid analysis

Abstract

In this thesis, a new DNA sample preparation microfluidic chip for Nucleic Acid (NA) probe assay has been proposed and fabricated using photosensitive glass and PDMS. The proposed microfluidic chip is composed of a mixer and a DNA purification chip. We have demonstrated that the fabricated mixer can achieve the mixing successfully for low Reynolds numbers below 50. At a flow rate of 1ml/min, mixing time on 120msec has been demonstrated. The fabricated DNA purification chip has shown a binding capacity of 15ng/㎠ and a minimum extractable input concentration of 100copies/200μL. We have demonstrated that the fabricated microfluidic system can extract and purify DNAs from the sample solution with comparable results to a conventional commercial kit. These characteristics have demonstrated that the proposed microfluidic chip can be applied for low-cost and disposable microsystems for the sample preparation of nucleic acid probe assays. The NA probe assays typically include PCR to amplify the number of copies of DNA to a detectable level. The PCR technique requires a relatively pure DNA sample in aqueous solution, free of inhibitors during the PCR process. Therefore, the extraction and purification of nucleic acids from biological samples are the critical steps that should be carefully handled in the NA assays. In this thesis, we have proposed a new microfluidic chip to address this sample preparation process for NA probe assays. The proposed microfluidic system is composed of a micromixer and a DNA purification chip. In the mixer, the biological sample is mixed with lysis reagents to release the DNA into the solution and the lysed solution is mixed with chaotropic salt. In the DNA purification chip, the DNAs in the solution will bind to the exposed $SiO^{2}$ surface at a high concentration of chaotropic salt. Photosensitive glass has been chosen as a binding substrate because its process is simple and inexpensive compare to other alternative technologies such as sil...