Improved design and experimental demonstration of a bi-directional microfluidic driving system

Abstract

An improvement for a bi-directional driving system and experimental investigation had been performed in the present study. The bi-directional driving module combines two individual components for suction and exclusion. The airflow passes through the air tunnel of the suction component with constriction; therefore, the individual suction component provides suction due to the Bernoulli’s equation. The individual exclusion component produces exclusion through the pneumatic structure, which leads the airflow to the microchannel when the airflow passes through the air tunnel of this component. A driving module with bi-directional pumping provides the net effect of suction or exclusion by adjusting the inlet flow rates for the suction and exclusion components and can be applied on the reaction chip for specific uses. The liquid column of samples and reagents in the microchannel can be hydrostatically pumped forward, backward and stop under control by this driving module and the pneumatic driver without microfabricated electrodes or heaters is most suitable for micro total analysis systems (μTAS). The individual components can be combined either by using a T-shape connection or parallel connectors. The parallel connector includes one vertical microchannel and two horizontal microchannels. The parallel connections of the individual components were explored in three different designs with different widths of vertical and horizontal microchannels. It was observed that the narrow microchannels in both vertical and horizontal microchannels of the design with parallel connection at the junction synthesized the suction and exclusion effects and reduced the interference with the two individual components. The results indicate that the operating range of the parallel-connected driving module with narrow microchannels at the junction is widest and the output liquid velocities exhibit good predictability.