Precise Dispensing Technology Using Electroformed Tubes for Micro-Volume Blood Diagnosis.

Abstract

Precise dispensing of droplets is a crucial step for acquiring reliable blood diagnostic results. When the source sample volume is limited, the need for precise dispensing of submicroliter and nanoliter quantities is especially important. In this paper, we developed a positive-displacement high-precision dispensing technique using a nickel electroformed tube with an inner diameter accuracy of n}{}5~mu text{m}n or less. When dispensing variation of 100 nL was evaluated by using a photometric method, the most stable coefficients of variation (CV) were observed for a tube thickness of n}{}50~mu text{m}n with hydrophobic treatment, where the average CV value was 1.3%, i.e., 1.3 nL. Furthermore, the glucose concentration of 100- and 200-nL animal-based control serum was colorimetrically measured using enzymatic reactions without drying and mixing reagents. The CV value was approximately 6.36% at 100 nL and 3.23% at 200 nL, suggesting that several biochemical panels can be precisely measured even from less than one drop of blood. This positive-displacement dispenser ensures zero contamination and almost-zero dead volume, thus it would be useful for multi-panel clinical blood testing.