Microfluidic device with capillary chamber

A microfluidic device comprising:

• a microfluidic channel dimensioned to cause flow of fluid by capillary action, the microfluidic channel having a first dimension proximate to a capillary chamber;
• the capillary chamber fluidly connected to the microfluidic channel, and the capillary chamber having an inlet with a second dimension proximate to the microfluidic channel wherein the second dimension is different than the first dimension, wherein:
• a transition between the microfluidic channel and the capillary chamber, including the difference between the second dimension of the inlet of the capillary chamber and the first dimension of the microfluidic channel, and surface tension of the fluid cause occurrence of a meniscus in the fluid and the meniscus is to break the capillary action and to cause a restriction of the flow of fluid therethrough;
• a fluidic actuator positioned proximate to the inlet of the capillary chamber, the fluidic actuator to actuate to displace fluid in the microfluidic channel proximate to the inlet of the capillary chamber and thereby cause flow of fluid through the capillary chamber by overcoming the restriction of the flow of fluid;
• and
• a restriction section fluidly connected to the microfluidic channel and the capillary chamber, the restriction section having a third dimension proximate to the capillary chamber, the third dimension being different than the second dimension, and another transition between the restriction section and the capillary chamber, including the difference between the third dimension and the second dimension, and surface tension of the fluid cause occurrence of another meniscus and the other meniscus is to cause restriction of the flow of fluid initiated by actuation of the fluidic actuator, wherein the other meniscus is formed at the restriction section in response to flow of a predetermined volume of fluid through the capillary chamber.

A method for a microfluidic device comprising:

• moving fluid from a reservoir to a capillary chamber via a capillary action within a microfluidic channel fluidly connected therebetween, the microfluidic channel having a first dimension proximate to the capillary chamber and the capillary chamber having a second dimension proximate to the microfluidic channel;
• restricting flow of the fluid through the capillary chamber by causing occurrence of a meniscus in the fluid and breaking the capillary action via a transition between the first dimension of the microfluidic channel and the second dimension of the capillary chamber and a surface tension of the fluid, wherein the second dimension is different than the first dimension;
• and
• actuating a fluidic actuator disposed in the microfluidic channel proximate to an inlet of the capillary chamber from the microfluidic channel to displace fluid in the microfluidic channel and initiate flow of the fluid through the capillary chamber by overcoming the restriction of the flow of fluid.