To create a small, portable, fully automated biosensor, a compact means of fluid handling is required. We designed, manufactured, and tested a "fluidics cube" for such a purpose. This cube, made of thermoplastic, contains reservoirs and channels for liquid samples and reagents and operates without the use of any internal valves or meters; it is a passive fluid circuit that relies on pressure relief vents to control fluid movement. We demonstrate the ability of pressure relief vents to control fluid movement and show how to simply manufacture or modify the cube. Combined with the planar array biosensor developed at the Naval Research Laboratory, it brings us one step closer to realizing our goal of a handheld biosensor capable of analyzing multiple samples for multiple analytes.

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IEF is a powerful technique which separates proteins and other amphoteric solutes in a pH gradient according to their pI's. The current work evaluates the effect on resolution of increasing electric fields in a novel preparative, vortex-stabilized electrophoresis device. In shallow gradients spanning one pH unit, the variants of myoglobin were separated at applied voltages from 10 to 15 kV. Digital imaging of these separations indicated a 20% reduction in bandwidth and a 60% increase in resolution as the electric field strength is varied across this range. These results were confirmed by IEF-PAGE and ion-exchange chromatography.

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