Microfluidic device with vented microchambers

Abstract

A microfluidic device with a microfluidic circuit including an array of fluidly coupled microchambers. Each microchamber includes a reaction chamber and an associated vent chamber. The microfluidic circuit may be arranged so that a fluid sample introduced to microfluidic device flows into the reaction chamber and air or other gas present in the reaction chamber is vented from the microchamber through the vent chamber. The microchamber may be configured to allow only the flow of air into the vent chamber from the reaction chamber until the air has been displaced from the reaction chamber by the fluid sample and/or a predefined volume of the fluid sample has been received in the reaction chamber. The microchamber may be further configured to release the fluid sample to thereafter flow from the reaction chamber into the vent chamber.

What is claimed is: 
     
         1 . A method of handling a fluid sample, comprising:
 providing a microfluidic device for handling a fluid sample, the microfluidic device comprising:
 at least one microfluidic well configured to receive the fluid sample, the at least one microfluidic well comprising:
 a primary inlet fluidly coupled to an inlet microfluidic channel, 
 the inlet microfluidic channel fluidly coupled to a plurality of parallel microfluidic channels at inlet ends of the parallel microfluidic channels, each microfluidic channel comprising a plurality of microchambers arranged in series that are fluidly coupled, via an outlet end, to an outlet microfluidic channel, 
 the outlet microfluidic channel fluidly coupled to a primary vent configured to vent gas from the parallel microfluidic channels, 
 wherein each microchamber comprises a reaction chamber configured to receive the fluid sample and a vent chamber configured to vent gas from the reaction chamber as the fluid sample flows into the reaction chamber, 
 wherein the reaction chamber is fluidly coupled to a corresponding microfluidic channel via an inlet and the vent chamber is fluidly coupled to said corresponding microfluidic channel via an outlet, 
 wherein the reaction chamber is configured to flow the fluid sample to the vent chamber after the gas has been vented to the outlet 
 
   applying a flexible plate seal to a top of the microfluidic device and over the at least one microfluidic well;   loading the fluid sample into each microchamber by moving the fluid sample through the microfluidic channel; and   compressing a bottom seal of the microfluidic device to block off the microfluidic channel and isolate the fluid sample held by each of the microchamber.   
     
     
         2 . The method according to  claim 1 , wherein the microfluidic device is placed into an instrument after applying a flexible plate seal to a top of the microfluidic device and over the at least one microfluidic well. 
     
     
         3 . The method according to  claim 2 , wherein the instrument is for conducting a dPCR technique on the fluid sample. 
     
     
         4 . The method according to  claim 2 , wherein the microfluidic device is thermocycled by the instrument to expose the fluid sample to cycles of repeated heating and cooling. 
     
     
         5 . The method according to  claim 4 , wherein the microfluidic device is imaged by the instrument to count the number of positive microchambers. 
     
     
         6 . The method according to  claim 2 , wherein the flexible plate seal is pressed into the primary inlet to move the fluid sample through the microfluidic channel. 
     
     
         7 . The method according to  claim 6 , wherein the flexible plate seal is pressed into the primary inlet by using a piston or other suitable device. 
     
     
         8 . The method according to  claim 1 , wherein a roller is used to compress the bottom seal of the microfluidic device. 
     
     
         9 . The method according to  claim 1 , wherein the reaction chamber is larger than the vent chamber. 
     
     
         10 . The method according to  claim 1 , wherein the vent chamber is configured with a narrow hydrophobic stricture to initially prevent flow of the fluid sample from the reaction chamber while allowing flow of gas from the reaction chamber as the fluid sample flows into the reaction chamber. 
     
     
         11 . The method according to  claim 10 , wherein the vent chamber is configured to release flow of the fluid sample from the reaction chamber when the gas has been vented from the reaction chamber. 
     
     
         12 . The method according to  claim 1 , wherein the reaction chamber has a diameter D and the vent chamber has a length L extending in a direction along the plurality of microfluidic channels arranged in parallel and a width W extending in a direction perpendicular to the length,
 wherein the vent chamber has a diameter-to-width ratio based on the diameter (D) of the reaction chamber compared to the width (W) of the vent chamber of D/W≥2 and length-to-width ratio based on the length (L) and width (W) of the vent chamber of L/W≥0.7.   
     
     
         13 . The method according to  claim 12 , wherein the vent chamber has a length-to-width ratio of L/W≥0.8. 
     
     
         14 . The method according to  claim 12 , wherein the reaction chamber has a diameter D≤600 μm. 
     
     
         15 . The method according to  claim 14 , wherein the reaction chamber has a depth-to-diameter ratio d/D of about 1.5. 
     
     
         16 . The method according to  claim 14 , wherein the reaction chamber has a diameter D of at least 60 μm. 
     
     
         17 . The method according to  claim 1 , wherein each reaction chamber has a depth d and each microfluidic channel comprising a plurality of microchambers has segments connecting the plurality of microchambers, wherein the segments have a depth d 2 , a ratio d/d 2  of the reaction chamber depth to the microfluidic channel segment depth being no more than 2:1. 
     
     
         18 . The method according to  claim 17 , wherein the vent chamber has a depth which is at least 50% of the reaction chamber depth. 
     
     
         19 . A method of handling a fluid sample, comprising:
 providing a microfluidic device for handling a fluid sample, the microfluidic device comprising:
 at least one microfluidic well configured to receive the fluid sample; and 
 a microfluidic circuit provided in the at least one microfluidic well, the microfluidic circuit configured to distribute the fluid sample within the at least one microfluidic well; 
 the microfluidic circuit including a plurality of reaction chambers, at least one microfluidic channel fluidly coupling the plurality of reaction chambers, and a plurality of microfluidic valves associated with the plurality of reaction chambers, each microfluidic valve being fluidly coupled to an associated reaction chamber; 
 each reaction chamber configured to receive a fluid sample from the at least one microfluidic channel and each microfluidic valve configured to vent gas from a corresponding reaction chamber via the at least one microfluidic channel as the fluid sample flows into the reaction chamber, 
 wherein each reaction chamber is arranged in the microfluidic circuit to receive fluid from an upstream segment of the at least one microfluidic channel and each microfluidic valve is arranged in the microfluidic circuit to deliver fluid to a downstream segment of the at least one microfluidic channel; 
   applying a flexible plate seal to a top of the microfluidic device and over the at least one microfluidic well;   loading the fluid sample into each reaction chamber by moving the fluid sample through the microfluidic circuit; and   compressing a bottom seal of the microfluidic device to block off the at least one microfluidic channel and isolate the fluid sample held by each of the reaction chamber.