Handling individual mammalian embryos using microfluidics.

We have designed, built, and tested microfluidic systems capable of transporting individual, preimplantation mouse embryos (100-microm to 150-microm diameter) through a network of channels. Typical channels are 160 to 200 microm deep, 250 to 400 microm wide at the top, and narrower at the bottom (0 to 250 microm wide) due to the fabrication process. In these channels, a pressure gradient of 1 Pa/mm causes the medium to flow on the order of 10(-10) m3/s (100 nl/s), with an average speed of 1 to 2 mm/s. Under these flow conditions the embryos roll along the bottoms of the channels, traveling at 1/2 the speed of the fluid. By manipulating the pressure at the wells connected to the ends of the channels, the embryos can be transported to (and retained at) specific locations including culture compartments and retrieval wells.

Integrating microfabricated fluidic systems and NMR spectroscopy.

The philosophy of miniature total analysis systems (mu-TAS) hinges on the integration of multiple chemical processing steps and the means of analyzing their results on the same miniaturized system. We have constructed chip-based capillary electrophoresis (CE) devices equipped with an integrated planar radio-frequency detector coil used for nuclear magnetic resonance spectroscopy (NMR). Separations were accomplished in the devices, but satisfactory NMR spectra could only be obtained from samples of high concentration. The relative sensitivity is explained and the scaling law dichotomy of CE and NMR explored.