Microfluidic valve, method for its manufacture, and uses thereof

1 . A method for the manufacture of a microfluidic valve, wherein said method comprises performing the following steps:

forming a structural portion of the valve by arranging a substrate, wherein said substrate comprises a mechanically inert material;

forming a functional portion of the valve by printing a succession of filaments of a mechanically responsive material comprising a liquid crystal polymer (LCP);

depositing the filaments on the substrate while applying an anti-adhesion treatment on one or more interfaces of said filaments and the substrate;

wherein the substrate and the filaments together at least partially define a fluid flow channel of the valve, wherein the filaments are arranged within the fluid flow channel, such that variations in at least one physicochemical parameter cause contraction or expansion of the mechanically responsive material along a longitudinal or transversal direction of the filaments, thereby modulating fluid flow rate through the channel.

2 . The method according to claim 1 , wherein the filaments are arranged in the fluid flow channel as a plurality of substantially parallel filaments, forming a rectangular or square surface.

3 . The method according to claim 1 , wherein the filaments are arranged in the fluid flow channel adopting a substantially planar radial distribution, wherein each filament starts from a central region common to all the filaments.

4 . The method according to claim 1 , wherein the filaments are arranged in the fluid flow channel as a substantially planar azimuthal or spiral distribution starting from a central region common to at least some of the filaments.

5 . The method according to claim 1 , further comprising adding a coupling agent between at least one part of the filaments and the substrate.

6 . The method according to claim 5 , wherein the coupling agent is a hybrid organic-inorganic coupling agent.

7 . The method according to claim 1 , wherein the anti-adhesion treatment comprises at least one of the group consisting of:

adding a chemical agent with anti-adhesion capability to the filaments;

introducing micro-roughness on a surface of the substrate onto which the filaments are to be deposited;

selecting a material with a surface energy lower than 40 mJ/m 2 for the manufacture of the substrate or the filaments;

applying an anti-adhesion coating on the substrate or on the filaments; and

arranging the filaments on the substrate to provide spatial separation.

8 . The method according to claim 7 , wherein the chemical agent comprises one or more long-chain aliphatic or fluorinated modifiers.

9 . The method according to claim 1 , further comprising a step of arranging one or more layers of a mechanically inert material after printing the filaments, configuring one or more additional elements of the structural portion of the valve.

10 . The method according to claim 9 , further comprising a step of applying an anti-adhesion treatment to the one or more layers of the mechanically inert material in the arranging step.

11 . The method according to claim 1 , comprising a step of applying a curing treatment after finishing the printing of the filaments.

12 . The method according to claim 11 , wherein the curing treatment is performed selectively in certain regions of the valve, or wherein the curing treatment comprises applying a succession of multiple curing operations on said regions.

13 . The method according to claim 1 , wherein the filaments are successively printed so as to form a three-dimensional shape.

14 . The method according to claim 13 , wherein the filaments are successively printed so as to form a conical shape.

15 . A valve for regulating a flow of a fluid through a microfluidic device, wherein the valve is manufactured by the method according to claim 1 .

16 . The valve according to claim 15 , wherein the mechanically responsive material comprises a main-chain LCP with reactive acrylate end groups and one or more photoinitiators.

17 . The valve according to claim 15 , wherein the LCP exhibits a mechanical response when exposed to a change in light, temperature, humidity, pH or electromagnetic field.

18 . The valve according to claim 15 , wherein the LCP is capable of responding to light photothermally or photochemically.

19 . The valve according to claim 18 , wherein the LCP comprises azobenzene, spiropyran, diarylethene, rotaxane, absorbent nanoparticles, or absorbent chromophores.

20 . The valve according to claim 15 , wherein the substrate comprises PDMS or a cyclic olefin polymer structure.

21 . The valve according to claim 15 , wherein the structural portion of the valve comprises:

one or more anti-adhesion openings arranged between the structural portion and the mechanically responsive material of the filaments; and/or

micro-roughness arranged between the structural portion and the mechanically responsive material of the filaments; and/or

a mechanically inert material with a surface energy lower than 40 mJ/m 2 ; and/or

an anti-adhesion coating.

22 . A peristaltic pump comprising a successive arrangement of two or more valves according to claim 15 or one or more valves according to claim 15 in combination with a passive flow restriction element.

23 . A microfluidic system comprising:

a valve according to claim 15 ; and

an actuator of said valve adapted for regulating the at least one physicochemical parameter to which the mechanically responsive material configuring the functional portion of the valve is sensitive.

24 . The system according to claim 23 , wherein the actuator comprises a lighting subsystem, a temperature regulation subsystem, a humidity regulation subsystem, a pH regulation subsystem, or an electromagnetic field regulation subsystem.

25 . A microfluidic valve comprising: the valve according to claim 15 configured for in vitro biomedical analyses, the manufacture of organ-on-a chip devices, drug screening analysis, in vitro biological studies, the monitoring and control of environmental pollution, biological risk detection, or food analysis.