Carbon dioxide priming of micro liquid systems

Abstract

Different methods for the complete priming of micro liquid systems with water were investigated. A new method was found using a carbon dioxide purge, which avoids the known problems with unremovable air bubble inclusions. Under the assumption that the surface tension of the liquid at the silicon interface is the main factor preventing priming, liquids with low surface tension and wetting angle are commonly used. In this work the solubility of the enclosed gas in the priming liquid is used in order to remove the bubbles. From that idea it becomes obvious first to prime the microfluid system with carbon dioxide CO, at room temperature and normal pressure, because the solubility of CO, in water is three decades larger than that for air (Ofl,) in water. With that procedure microfluidic systems with hydrophillic and hydrophobic surfaces (silicon, plastic) can be safely, fast and reproducibly primed with water.