System and self-metering cartridges for point of care bioassays

A device for performing a bioassay on a biological sample to determine the presence or quantity of one or more biomolecules when connected to an appliance that provides pressure and vacuum sources and a detection station, the device comprising:

• a planar body comprising a sample chamber, a first conduit, at least one reagent chamber, at least one metering chamber, at least one mixing chamber and at least one detection chamber, wherein:
• the sample chamber has oblong dimensions with a top and a bottom and has a first inlet at its top for accepting a biological sample or a sample fluid containing a biological sample, a lid for sealing the first inlet after a biological sample or sample fluid is inserted, a vent port at its top allowing the passage of air but not liquid, and an outlet at its bottom connected to a first conduit, wherein the vent port is capable of being sealingly connected to a valve in the appliance;
• the metering chamber having a top and a bottom such that the bottom of the metering chamber is (a) connected to and in fluid communication with a reagent chamber, (b) connected to and in fluid communication with the outlet of the sample chamber through the first conduit, (c) connected at the top of the metering chamber to a metering vent port, and (d) connected at the top of the metering chamber to and in fluid communication with a mixing chamber conduit, wherein the metering vent port is capable of being sealingly connected to a valve in the appliance;
• the reagent chamber capable of containing assay reagents, the reagent chamber being connected to the bottom of the metering chamber by a passage and connected to a reagent vent port allowing the passage of air but not liquid, wherein the reagent vent port is capable of being sealingly connected to a valve and pump in the appliance so that the reagent port is capable of accepting air pressure for forcing the assay reagents into the bottom of metering chamber;
• the first conduit being connected to and providing fluid communication between the outlet of the sample chamber and the bottom of the metering chamber and being in fluid communication with the passage connecting the reagent chamber to the bottom of the metering chamber, wherein fluid occupying the first conduit has a fluid resistance such that whenever pressure is applied to the reagent chamber from the reagent vent port a flow of reagents from the reagent chamber moves substantially only into the metering chamber;
• the mixing chamber for mixing the biological sample or sample fluid with the assay reagents, the mixing chamber having a top and a bottom and being in fluid communication with the metering chamber by a passage connecting the bottom of the mixing chamber to the top of the metering chamber, the mixing chamber being connected at its top to a mixing vent port that allows the passage of air but not liquid, wherein the mixing vent port is capable of being sealingly connected to a valve in the appliance, wherein the mixing chamber or the reagent chamber or both chambers contain a predetermined quantity of wax having a melting temperature such that the wax forms a bubble-preventing layer on a reaction mixture whenever the mixing chamber is above the melting temperature;
• the detection chamber has a top and a bottom and is in fluid communication with the mixing chamber by a passage connecting the bottom of the detection chamber to the bottom of the mixing chamber, and the detection chamber is connected at its top to a detection vent port that allows the passage of air but not liquid, wherein the detection vent port is capable of being sealingly connected to a valve and vacuum source in the appliance so that the detection port is capable of accepting a vacuum for drawing the mixture of assay reagents and biological sample or sample fluid into the bottom of detection chamber from the mixing chamber.