Microtechnology For Realization Of Dielectrophoresis Enhanced Microwells For Biomedical Applications

Microtechnologies are widely used in many applications as e.g. for the automotive or telecommunication industry. But it could be also a versatile tool for biological and biomedical applications. Microwells have been established long in this application field but remained without any additional functionality up to now. Merging new fabrication techniques and handling concepts with microelectronics enables the realization of intelligent microwells suitable for future applications e.g. improved cancer treatment. For the implementation of a dielectrophoresis enhanced microwell device a technology based on standard PCB technology has been developed. But as materials from PCB technology are not biocompatible new materials have to be selected, tested and processes adapted to these new packaging materials. With promising preselected materials for an enhanced microwell device biocompatibility tests have been carried out. As base conducting metal layer aluminum has been selected. Different dielectric materials were evaluated with focus on their processability. Goal of this preselection study was to find materials, which allow a fine structuring and realization of thin layers for the required application geometries. Thin aluminum foils are structured by laser micro machining and laminated successively to obtain minimum registration tolerances of the respective layers. The microwells are also laser machined into the laminate, allowing capturing and handling individual cells within a dielectrophoretic cage realized by the structured aluminum as well as providing access holes for the layer-to-layer interconnection. Furthermore, surface treatments with e.g. thiols and fluorinated acrylates on different materials were inspected by surface tension and wetting analysis to allow designing the hydrophilic/hydrophobic microfluidic networks required for the microwell device. First demonstrators are presenting the developed technologies and structures realized. In summary this paper descri- bes the material selection for a biocompatible microwell device, the development of the individual process steps and results on the microstructuring as well as on biocompatibility of the materials are given.