Alterative methods for fabricating lab-on-a-chip microfluidic platforms.

摘要

High temperature bonding and precise alignment are the major limitations in fabricating present day microfluidic devices. The novelty of the proposed research is to fabricate Lab-on-a-Chip (LOC) devices at a low temperature with the added benefit of maintaining precise alignment during the entire bonding process. The LOC devices were fabricated using photomasks as the substrates material and traditional microfabrication technologies like photolithography, wet etching, thin film deposition, and wafer level bonding. A room temperature "Stamp and Stick (SAS)" transfer bonding technique was developed to bond the LOC devices using a suitable UV curable adhesive.; The fabrication limitations encountered during SAS such as webbing, bleeding and non-bonding are addressed. Various adhesive thickness were explored to address the fabrication limitations and a polymer thickness of approximately 1.9 mum obtained at a spin speed of 8000 rpm and spin time of 60 seconds was selected to bond the final devices.; A study to further understand the fabrication limitations was also performed. In the study adhesive wall width, polymer thickness, spin speed, and spin time were varied. Adhesive wall widths of 200 mum and 400 mum were used and the devices were spun at 6000 rpm and 8000 rpm with spin time of 30 seconds and 60 seconds. From the study it was inferred that a polymer thickness of approximately 2-3mum was ideal to bond LOC devices using SAS. Webbing was due to the polymer thickness and the geometry. Bleeding was due to the adhesive wall width excess polymer thickness. Non-bonding was observed due to problems with planarization. However, in these devices, the channels were not clogged and leakage was not seen in these devices.; The fabricated devices were characterized with a mixture of dopamine (2.0mM) and catechol (2.0mM) in a phosphate buffer (20mM) solution. Both separation and detection of the analytes were achieved in the tested LOC devices. All of the eight electrochemical detection (ECD) electrodes in the array were capable of detecting dopamine with the amplitude of the signal (i.e., peak heights) decreasing as the electrodes distance from the channel exit increased. The overall performance of the new SAS LOC devices exceeded that of the previous thermally bonded devices.