Most clinical chemistry tests are performed on cell-free serum or plasma. Therefore micro assay devices for blood tests require integrated on-chip microfluidics for separation of plasma or serum from blood. Polymers are ideally suited for these applications due to their material properties and their applicability for high volume production. These requirements are achieved by a new on-chip blood separation technique based on microchannel bend structures and a rapid processing technology for micro assay devices using injection molding or hot embossing. Different prototype polymer chips with channel dimensions down to 20 μm and aspect ratios of 4 have been fabricated by injection molding and hot embossing. The inserts for the molding tools were fabricated by an UV-LIGA technology.
The separation efficiency of these chips has been tested with human blood samples. The results show different separation efficiencies up to 100 % for blood cells and plasma depending on microchannel geometry as well as cell concentration. As compared to present microfluidic devices for the separation of blood cells like filters, membranes or filtration by diffusion the microchannel bend is an integrated on-chip blood separation method. It combines the advantages of rapid separation times and a simple geometry that leads to cost-effective high volume production using injection molding.
Microfluidic devices are mainly used within the life sciences or chemical analysis. Polymers are ideally suited for these applications due to their physical and chemical properties. In this report, we describe a rapid low cost processing technology to fabricate mold inserts for microfluidic structures with high aspect ratio, as well as excellent surface quality and high hardness. These tools are used for hot embossing and as mold inserts for injection molding. They enable cost effective structuring of technical polymers like polycarbonate or cycloolefin copolymer. The main advantage of our approach is the availability of the geometry and the specific target material right from the start of the evaluation process of microfluidic devices. The process described enables a rapid prototyping for the development and evaluation of different microfluidic devices, and they can be used for a low-cost mass production of micro structured parts.
Biological applications of micro assay devices require easy implementable on-chip microfluidics for separation of plasma or serum from blood. This is achieved by a new blood separation technique based on a microchannel bend structure developed within the collaborative Micro-Tele-BioChip (μTBC) project. Different prototype polymer chips have been manufactured with an UV-LIGA process and hot embossing technology. The separation mechanisms have been identified and the separation efficiency of these chips has been determined by experimental measurements using human blood samples. Results show different separation efficiencies for cells and plasma up to 100 % depending on microchannel geometry, hematocrit, and feed velocity. This novel technique leads to an alternative blood separation method as compared to existing micro separation technologies.
Biological applications of micro assay devices require integrated on-chip microfluidics for separation of plasma or serum from blood. This is achieved by a new blood separation technique based on a microchannel bend structure developed within the collaborative Micro-Tele-BioChip (μTBC) project co-funded by the German Ministry For Education and Research (BMBF). Different prototype polymer chips have been manufactured with an UV-LIGA process and hot embossing technology. The separation efficiency of these chips has been determined by experimental measurements using human whole blood. Results show different separation efficiencies for cells and plasma depending on microchannel geometry and blood sample characteristics and suggest an alternative blood separation method as compared to existing micro separation technologies.
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