FLOW CELLS

1 . A flow cell, comprising:

a substrate;

a plurality of reactive regions spatially separated from one another across the substrate, each of the plurality of reactive regions including:

a polymeric hydrogel layer; and

a reactive entity attached to the polymeric hydrogel layer; and

a plurality of independently removable coatings respectively positioned over each of the plurality of reactive regions;

wherein at least one of the plurality of independently removable coatings is a composite that includes a thermo-responsive polymer and a photo-thermal additive.

2 . The flow cell as defined in claim 1 , wherein the reactive entity in each of the plurality of reactive regions is a primer set.

3 . The flow cell as defined in claim 2 , wherein the primer set is the same in each of the plurality of reactive regions.

4 . The flow cell as defined in claim 2 , wherein the primer set of at least one of the plurality of reactive regions is different than the primer set of at least one other of the plurality of reactive regions.

5 . The flow cell as defined in claim 1 , wherein:

the substrate includes a plurality of depressions;

each of the plurality of reactive regions is positioned within a respective one of the plurality of depressions; and

each of the plurality of independently removable coatings covers a respective one of the plurality of reactive regions.

6 . The flow cell as defined in claim 1 , wherein:

the substrate includes a plurality of protrusions;

each of the plurality of reactive regions is positioned at a respective one of the plurality of protrusions; and

each of the plurality of independently removable coatings covers a respective one of the plurality of protrusions.

7 . The flow cell as defined in claim 1 , wherein the thermo-responsive polymer is selected from the group consisting of polylactic acid, poly(lactic-co-glycolic) acid, polycaprolactone, agarose, wax, poly(acrylamide-co-acrylonitrile), poly(N-isopropylacrylamide), cyclodextrin, polyethylene glycol homopolymer, polyethylene glycol graft copolymer, polyethylene block copolymer, and combinations thereof.

8 . The flow cell as defined in claim 1 , wherein the photo-thermal filler is selected from the group consisting of gold nanoparticles, silver nanoparticles, iron oxide nanoparticles, polypyrrole, graphene, carbon nanotubes, carbon nanodots, black phosphorus, azobenzene, and combinations thereof.

9 . A method, comprising:

selectively removing at least one of a plurality of independently removable coatings respectively positioned over each of a plurality of reactive regions spatially separated from one another across a substrate, thereby exposing at least one of the plurality of reactive regions and a reactive entity at the at least one of the plurality of reactive regions;

wherein each of the plurality of reactive regions includes a polymeric hydrogel layer and the reactive entity attached to the polymeric hydrogel layer; and

wherein at least one of the plurality of independently removable coatings is a composite including a thermo-responsive polymer and photo-thermal additive; and

initiating a reaction involving the reactive entity.

10 . The method as defined in claim 9 , wherein selectively removing the at least one of the plurality of independently removable coatings involves:

exposing the at least one of the plurality of independently removable coatings to light, thereby rendering the at least one of the plurality of independently removable coatings that has been exposed to the light susceptible to removal using an aqueous solvent; and

removing the at least one of the plurality of independently removable coatings using the aqueous solvent.

11 . The method as defined in claim 9 , wherein:

the substrate includes a plurality of depressions;

each of the plurality of reactive regions is positioned within a respective one of the plurality of depressions; and

each of the plurality of independently removable coatings covers a respective one of the plurality of reactive regions.

12 . The method as defined in claim 9 , wherein:

the substrate includes a plurality of protrusions;

each of the plurality of reactive regions is positioned at a respective one of the plurality of protrusions; and

each of the plurality of independently removable coatings covers a respective one of the plurality of protrusions.

13 . The method as defined in claim 9 , wherein the thermo-responsive polymer is selected from the group consisting of polylactic acid, poly(lactic-co-glycolic) acid, polycaprolactone, agarose, wax, poly(acrylamide-co-acrylonitrile), poly(N-isopropylacrylamide), cyclodextrin, polyethylene glycol homopolymer, polyethylene glycol graft copolymer, polyethylene block copolymer, and combinations thereof.

14 . The method as defined in claim 9 , wherein the photo-thermal filler is selected from the group consisting of gold nanoparticles, silver nanoparticles, iron oxide nanoparticles, polypyrrole, graphene, carbon nanotubes, carbon nanodots, black phosphorus, azobenzene, and combinations thereof.

15 . The method as defined in claim 9 , wherein the reactive entity in each of the plurality of reactive regions is a primer set.

16 . The method as defined in claim 15 , wherein the primer set is the same in each of the plurality of reactive regions.

17 . The method as defined in claim 15 , wherein the primer set of at least one of the plurality of reactive regions is different than the primer set of at least one other of the plurality of reactive regions.