Patent ID: 9726588
Date: 2017-08-08
CPC Classifications: B01L,G01N

Claim:
1. A method of flowing a fluid sample through a micro fluidic channel in a passive micro fluidic device by capillarity, the method comprising: providing a passive microfluidic device comprising an inlet reservoir, an outlet reservoir and a microfluidic channel having an inlet and an outlet and extending between the inlet reservoir and the outlet reservoir, wherein at least one portion of the channel is provided with a structural feature arranged to decrease or increase capillary flow rate of a fluid through the channel; and introducing an aqueous fluid sample into the inlet reservoir and allowing the fluid sample to flow via the inlet through the channel by capillarity to the outlet, wherein the method comprises the step of adding first and second flow control reagents to the fluid within the inlet reservoir or prior to introduction of the fluid sample into the inlet reservoir, and wherein the first flow control reagent is a surfactant which reduces the surface tension of the fluid and the second flow control reagent is a surfactant viscosity enhancer, wherein for a given concentration of each of the first and second flow control reagents in an aqueous fluid the second flow control reagent has a greater effect on increasing fluid viscosity than the first flow control reagent, and wherein the structural feature of the channel arranged to decrease or increase fluid flow rate is independently selected from the group consisting of a delay loop, an increase or decrease in any cross-sectional dimension of the channel, or a variation in material forming the channel walls.