Reagent delivery networks

1 . A reagent delivery network, comprising:

an inlet microfluidic channel;

a microfluidic cross-channel branching off from the inlet microfluidic channel,

wherein the microfluidic cross-channel includes:

a constriction region, and

a reagent storage chamber having reagent therein;

an outlet microfluidic channel having a side-wall opening connected to the microfluidic cross-channel, the outlet microfluidic channel configured to receive fluid from the microfluidic cross-channel;

a first resistor positioned along the inlet microfluidic channel at a location and configured to redirect fluid from the inlet microfluidic channel into the microfluidic cross-channel;

a second resistor positioned at a location within the outlet microfluidic channel directly opposite the first resistor and configured to pull the fluid received from the inlet microfluidic channel through the microfluidic cross-channel down towards a microfluidic processing channel,

wherein actuation of the first resistor pushes the fluid into the microfluidic cross-channel without passing into the outlet microfluidic channel, and actuation of the second resistor pulls the fluid from the microfluidic cross-channel into the outlet microfluidic channel toward the microfluidic processing channel; and

a controller configured to mix the fluid by, repeatedly:

actuating the second resistor to flow the fluid back toward the first resistor and actuating the first resistor to push the fluid toward the second resistor.

2 . The reagent delivery network of claim 1 , wherein the first resistor is adapted to operate at a power density sufficient to break a capillary retention meniscus at the constriction region and deliver fluid from the inlet microfluidic channel and into the reagent storage chamber.

3 . The reagent delivery network of claim 2 , wherein the power density of the first resistor ranges from 100 MW/m 2 to 1,000 MW/m 2 .

4 . The reagent delivery network of claim 1 , wherein the microfluidic cross-channel further includes a second constriction region adjacent to the outlet microfluidic channel.

5 . The reagent delivery network of claim 1 , further including a chamber resistor located within the reagent storage chamber to generate mixing of the reagent with fluid introduced through the constriction region.

6 . The reagent delivery network of claim 1 , wherein the reagent is a dried reagent to be reconstituted by fluid when introduced through the constriction region.

7 . The reagent delivery network of claim 1 , comprising

multiple microfluidic cross-channels fluidically independently coupling the inlet microfluidic channel with the outlet microfluidic channel in series, wherein the multiple microfluidic cross-channels include:

the microfluidic cross-channel, and

a second microfluidic cross-channel having a second reagent storage chamber having a second reagent stored therein;

a third resistor positioned along the inlet microfluidic channel at a second location and configured to cause the fluid to flow through a second constriction region and into the second reagent storage chamber, wherein actuation of the first resistor causes the fluid to flow through the constriction region and does not cause the fluid to flow through the second constriction region, and wherein actuation of the third resistor causes the fluid to flow through the second constriction region and does not cause the fluid to flow through the constriction region.

8 . The reagent delivery network of claim 7 , wherein the reagent and the second reagent independently include a nucleic acid primer, a secondary antibody, a PCR mastermix component, an optical marker; or a mixture thereof.

9 . The reagent delivery network of claim 1 , wherein the reagent delivery network is fluidly coupled in series with a second reagent delivery network, wherein the outlet microfluidic channel fluidically feeds into or is a second inlet microfluidic channel of the second reagent delivery network.

10 . The reagent delivery network of claim 1 , further comprising a second reagent delivery network including a second inlet microfluidic channel, a second microfluidic cross-channel branching off from the second inlet microfluidic channel, and a second outlet microfluidic channel, wherein the outlet microfluidic channel of the reagent delivery network and the second outlet delivery channel of the second reagent delivery network are fluidly coupled in parallel to the microfluidic processing channel.

11 . A method of reconstituting reagent, comprising:

flowing fluid into an inlet microfluidic channel of a reagent delivery network, the reagent delivery network comprising:

the inlet microfluidic channel;

a microfluidic cross-channel branching off from the inlet microfluidic channel,

wherein the microfluidic cross-channel includes:

a constriction region, and

a reagent storage chamber having reagent therein;

an outlet microfluidic channel having a side-wall opening connected to the microfluidic cross-channel, the outlet microfluidic channel configured to receive fluid from the microfluidic cross-channel;

a first resistor positioned along the inlet microfluidic channel at a location and configured to redirect fluid from the inlet microfluidic channel into the microfluidic cross-channel;

a second resistor positioned at a location within the outlet microfluidic channel directly opposite the first resistor and configured to pull the fluid received from the inlet microfluidic channel through the microfluidic cross-channel down towards a microfluidic processing channel,

wherein actuation of the first resistor pushes the fluid into the microfluidic cross-channel without passing into the outlet microfluidic channel, and actuation of the second resistor pulls the fluid from the microfluidic cross-channel into the outlet microfluidic channel toward the microfluidic processing channel;

forming a capillary retention meniscus at the constriction region of the microfluidic cross-channel branching off from the inlet microfluidic channel, wherein the microfluidic cross-channel includes the reagent storage chamber containing the reagent positioned beyond the constriction region;

firing the first resistor to generate a pressure change to break the capillary retention meniscus at the constriction region;

flowing the fluid through the constriction region and into the reagent storage chamber to combine the fluid with the reagent to form a reconstituted reagent; and

mixing, using a controller, the fluid by:

repeatedly actuating the second resistor to flow the fluid back toward the first resistor and actuating the first resistor to push the fluid toward the second resistor.

12 . The method of claim 11 , further comprising flowing the reconstituted reagent from the reagent storage chamber and into the outlet microfluidic channel.

13 . The method of claim 12 , further comprising mixing the reagent with the fluid in the reagent storage chamber to form the reconstituted reagent using:

chamber resistors located within the reagent storage chamber.

14 . The method of claim 11 , wherein after forming the reconstituted reagent, the method further comprises:

forming a second capillary retention meniscus at a second constriction region of a second microfluidic cross-channel branching off from the inlet microfluidic channel, wherein the second microfluidic cross-channel includes a second reagent storage chamber containing a second reagent positioned beyond the second constriction region;

firing a third resistor to generate a pressure change to break the second capillary retention meniscus at the second constriction region; and

flowing fluid through the second constriction region and into the second reagent storage chamber to combine fluid with the second reagent to form a second reconstituted reagent.