Micromachined pipette arrays

In this paper, the design and characterization of batch fabricated metallic micromachined pipette arrays is described. The process used to fabricate t he micromachined pipette arrays (MPA) includes p(+) etch-stop membrane tech nology, anisotropic etching of silicon in potassium hydroxide, sacrificial thick photoresist micromolding technology, and electrodeposition, Arrays of one to ten pipettes have been fabricated using nickel as the structural ma terial and palladium as the biocompatible coating of inside walls. The inne r dimensions of the individual pipettes fabricated to date range from 30 mu m to 1.5 mm in width, 0.5 mm to several cm in length, and 5-50 mu m in thi ckness. The center-to-center spacing of these pipettes varies from 100 mu m to several centimeters. The MPA have a number of advantages when compared to the current micropipette technology, including the ability to transfer p recise volumes of samples in the submicroliter range; the ability to manipu late samples, reagents, or buffers In a highly-parallel fashion by operatin g hundreds of individual pipettes simultaneously; and the compatibility wit h the submilimeter center-to-center dimensions of the microscale biochemica l analysis systems. The application of the MPA to high lane density slab ge l electrophoresis is explored. Sample wells are formed in agarose gels by u sing micromachined combs (solid MPA) at center-to-center spacing ranging fr om 250 mu m to 1.9 mm, The samples are loaded using the MPA, The results of the micro-gel separations compare favorably with the standard mini-gel sep arations and show a twofold increase in the number of theoretical plates as well as a sixfold increase in lane density.