National Research Council of Canada

A microfluidic valve comprises: a substrate, relief-patterned at top and bottom surfaces to define: an annular valve seat and a surface for holding an elastomeric membrane inside a generally cylindrical protuberance in the top surface so that the membrane covers the cylindrical inner wall. The relief patterning also provides a through bore defining one valved microfluidic channel and an annular trough around the annular valve seat to which at least one other valved microfluidic channel extends. When the cap is pushed into the recess, it reversibly presses the membrane against the valve seat to form a seal that prevents fluid flow in the channel.

A gravitationally checked microvalve for use in a microfluidic chip/device has a receptacle with a floor and at least one sidewall; a supply channel for non-capillary transport of liquid with an outlet into the receptacle; and an enclosure that permits pressurization-driven flow of tiny volumes of liquid with great control. The microvalve has an accretion surface surrounding the outlet on at least 3 sides thereof, that guides growth and formation of a bolus of the liquid from the supply channel to accrete volume at the outlet, by preventing spread of the liquid beyond the accretion surface, to draw a center of gravity of the bolus away from the sidewall. Once sufficient volume accretes, weight overbears adhesion, and the bolus falls. Preferably a slide is provided to guide the bolus's fall. As the fluid has fallen, gravity checks the valve after the fall. A vertical separation between the outlet and the floor is at least 5.5 mm to ensure checking.

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