Chambers to receive fluids by negative pressures

Abstract

An example device includes a chamber including a fluid inlet, a fluid outlet, and a negative-pressure port. The negative-pressure port is positioned relative to the fluid inlet to draw a droplet of a fluid from the fluid inlet into the chamber when the fluid is applied to the fluid inlet and negative pressure is applied to the negative-pressure port. The fluid outlet is positioned relative to the fluid inlet to collect the droplet. The example device further includes a downstream microfluidic channel connected to the fluid outlet of the chamber. The downstream microfluidic channel communicates capillary action to the fluid outlet of the chamber. The capillary action resists flow of the fluid from the fluid outlet into the chamber induced by the negative pressure applied to the negative-pressure port.

1 . A device comprising:
 a chamber including a fluid inlet, a fluid outlet, and a negative-pressure port, the negative-pressure port positioned relative to the fluid inlet to draw a droplet of a fluid from the fluid inlet into the chamber when the fluid is applied to the fluid inlet and negative pressure is applied to the negative-pressure port, the fluid outlet positioned relative to the fluid inlet to collect the droplet; and   a downstream microfluidic channel connected to the fluid outlet of the chamber, the downstream microfluidic channel to communicate capillary action to the fluid outlet of the chamber, the capillary action to resist flow of the fluid from the fluid outlet into the chamber induced by the negative pressure applied to the negative-pressure port.   
     
     
         2 . The device of  claim 1 , further comprising a droplet ejector at an end of the downstream microfluidic channel to eject droplets to draw fluid through the downstream microfluidic channel, the droplet ejector further to provide the capillary action. 
     
     
         3 . The device of  claim 2 , further comprising a target microfluidic network communicating with the downstream microfluidic channel between the chamber and the droplet ejector, the target microfluidic network to perform a process with the fluid. 
     
     
         4 . The device of  claim 3 , wherein the process comprises a nucleic acid amplification process. 
     
     
         5 . The device of  claim 1 , further comprising a droplet ejector connected to the negative-pressure port to provide the negative pressure. 
     
     
         6 . The device of  claim 1 , further comprising a magnet at the chamber. 
     
     
         7 . The device of  claim 1 , further comprising a dried reagent in the chamber. 
     
     
         8 . The device of  claim 1 , wherein the chamber is of a mesofluidic scale. 
     
     
         9 . The device of  claim 1 , wherein a capillary break separates the negative-pressure port from the fluid inlet or the fluid outlet. 
     
     
         10 . A method comprising:
 applying a negative pressure to a negative-pressure port of a chamber to draw a droplet of a fluid from a fluid inlet of the chamber into the chamber;   collecting the droplet at a fluid outlet of the chamber, the fluid outlet positioned below the fluid inlet relative to a force of gravity; and   communicating capillary action from a downstream microfluidic channel to the fluid outlet of the chamber, the capillary action to resist flow of the fluid from the fluid outlet into the chamber induced by the negative pressure applied to the negative-pressure port.   
     
     
         11 . The method of  claim 10 , further comprising ejecting droplets using a droplet ejector at an end of the downstream microfluidic channel to draw fluid through the downstream microfluidic channel. 
     
     
         12 . The method of  claim 11 , further comprising performing a process with the fluid at a target microfluidic network communicating with the downstream microfluidic channel between the chamber and the droplet ejector. 
     
     
         13 . The method of  claim 12 , comprising performing a nucleic acid amplification process with the fluid at the target microfluidic network. 
     
     
         14 . The method of  claim 10 , further comprising ejecting droplets using a droplet ejector connected to the negative-pressure port to apply the negative pressure to the negative-pressure port. 
     
     
         15 . A device comprising:
 a housing;   a chamber defined by the housing, the chamber including a fluid inlet, a fluid outlet, and a negative-pressure port;   a downstream microfluidic channel connected to the fluid outlet of the chamber, the downstream microfluidic channel to resist backflow of fluid from the fluid outlet into the chamber induced by negative pressure applied to the negative-pressure port;   a feature at the housing, the feature shaped to position the fluid outlet below the fluid inlet relative to a force of gravity when the feature is mated with a complementary feature at an analysis device; and   a signal interface to receive a signal from the analysis device to apply the negative pressure to the negative-pressure port to draw a droplet of fluid from the fluid inlet into the chamber.