Microfluidics and bioanalysis systems: issues and examples

Miniaturized fluid systems have emerged in recent years as a serious approach to improved performance and new functionality in the bioanalysis arena. Several important scaling issues are important in the design of fluid systems at the micro scale including surface to volume ratio, flow regime (Reynolds number) and connection and packaging issues. The authors have developed two microfluidic systems including an integrated capillary electrophoresis and nuclear magnetic resonance spectroscopy system and a system for the transport and handling of mammalian embryos. Both glass and polyimide-based systems were built to investigate the integration of capillary electrophoresis (CE) with nuclear magnetic resonance spectroscopy (NMR). Linewidths of 1.4 Hz have been demonstrated in the system. The authors have also designed, built, and tested a micro fluidic system capable of transporting individual, pre-implantation mouse embryos through a network of channels to selected locations. The flow of buffer causes the embryos to roll down the channels. Embryos can be spatially retained and then released or moved to a new location via the manipulation of flows. Typical embryo velocities of 80 μm/s were observed for 400 μm/s center line fluid velocities