Miniaturized Volumetric Dosing System for Automated Nanoliter Precision Dosing of Liquids

Inhalt:
Microfluidic tasks demand precise dosing. High precision is even more challenging for extremely small volume packages and current closed loop-controlled dosing systems for small volumes are large devices. To enable miniaturization, this study investigates the feasibility of a capacitive volume monitoring system in combination with micropumps. A pair of rectangular electrodes was mounted along glass capillaries to measure the capacitance change due to the change in filling level in the capillaries. The capacitive monitoring system was specifically fitted and optimized in spatial arrangement for the glass capillaries used. For system evaluation, the volume displacement was monitored gravimetrically. The best configuration was able to resolve single pumping strokes with minimal volumes of 25.1 nL and an average capacity change-to-volume ratio of 1.61 digits/nL. The general feasibility of the system was thus proven. Further research regarding additional influencing factors such as temperature is necessary. The presented approach allows the prospect of a closed loop system with a dosing precision of up to 25 nL.