# US 2019/0168217 A1 · Fluid flow device and method for making the same > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2019/0168217 A1 - Document ID: US20190168217A1 - Status: Published application - Kind: A1 - Application number: 16/306,255 - Filed: 2017-05-10 - Published: 2019-06-06 - Earliest claimed: 2016-06-02 - Assignees: University of Southampton - Applicants: University of Southampton - Inventors: Robert EASON; Collin SONES; loannis KATIS; Peijun HE - Web page: https://patentgrep.com/patent/US20190168217A1 ## CPC - B01L 3/502707: {characterised by the manufacture of the container or its components} - B01L 3/5023: {with a sample being transported to, and subsequently stored in an absorbent for analysis} - D21H 25/06: of impregnated or coated paper (D21H25/08 takes precedence) - G03F 7/0015: {Production of aperture devices, microporous systems or stamps} - G03F 7/095: having more than one photosensitive layer (G03F7/075 takes precedence) - G03F 7/0955: {one of the photosensitive systems comprising a non-macromolecular photopolymerisable compound having carbon-to-carbon double bonds, e.g. ethylenic compounds} - G03F 7/2006: {using coherent light; using polarised light} - G03F 7/2053: {using a laser (ablative removal B41C)} - G03F 7/70025: {by lasers} - G03F 7/70383: {Direct write, i.e. pattern is written directly without the use of a mask by one or multiple beams (maskless lithography using a programmable mask G03F7/70291)} - G03F 7/704: {Scanned exposure beam, e.g. raster-, rotary- and vector scanning (mask projection exposure involving relative movement of patterned beam and workpiece during imaging G03F7/70358)} - B01L 2200/12: Specific details about manufacturing devices - B01L 2300/126: Paper - B01L: CHEMICAL OR PHYSICAL LABORATORY APPARATUS FOR GENERAL USE - D21H: PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR - G03F: PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR; (phototypographic composing devices B41B; photosensitive materials or processes for photographic purposes G03C; electrophotography, sensitive layers or processes therefor G03G) ## Abstract Techniques for making fluid flow devices are described. The technique is based on radiation-induced conversion of a radiation-sensitive substance from a first state to a second state. With adjustment of the radiation parameters such as power and scan speed we can control the depths of barriers that are formed within a substrate which can produce 3D flow paths. We have used this depth-variable patterning protocol for stacking and sealing of multilayer substrates, for assembly of backing layers for two-dimensional (2D) lateral flow devices and for fabrication of 3D devices. Since the 3D flow paths can be formed via a single laser-writing process by controlling the patterning parameters, this is a distinct improvement over other methods that require multiple complicated and repetitive assembly procedures. ## Claims ### Claim 1 A method for making a fluid flow device, comprising: providing a stack comprising a plurality of layers, wherein at least one of the layers is made of porous material and at least part of at least one layer is impregnated with a radiation-sensitive substance; and after providing the stack, applying radiation onto at least part of the stack to change the radiation-sensitive substance from a first state to a second state through at least part of the thickness of the stack. ### Claim 2 (depends on 1) The method of claim 1, wherein in one of the first state and the second state, the radiation-sensitive substance is at least one of: less permeable to fluid than when in the other of the first state and the second state; more solid than when in the other of the first state and the second state; or less soluble to a developer than when in the other of the first state and the second state. ### Claim 3 (depends on 1) The method of claim 1, wherein the radiation is applied to a surface layer at a surface of the stack to change the radiation-sensitive substance from the first state to the second state in at least one layer other than said surface layer. ### Claim 4 (depends on 1) The method of claim 1, wherein the radiation is applied to change the radiation-sensitive substance from the first state to the second state in aligned parts of at least two layers of the stack. ### Claim 5 (depends on 1) The method of claim 1, wherein the radiation is applied to change the radiation-sensitive substance from the first state to the second state in selected parts of the stack to form regions intended to receive, contain, guide and/or control the flow of fluid during use of the device. ### Claim 6 (depends on 5) The method of claim 5, wherein at least one of the formed regions extends through at least two layers of the stack. ### Claim 7 (depends on 5) The method of claim 5, wherein the regions form at least part of a three-dimensional fluid flow network comprising at least one fluid flow path for permitting fluid flow between different layers of the stack. ### Claim 8 (depends on 1) The method of claim 1, wherein the radiation is applied to change the radiation-sensitive substance from the first state to the second state in part of the stack to bond at least two of the layers together. ### Claim 9 (canceled) ### Claim 10 (depends on 1) The method of claim 1, wherein at least one of the layers is partially impregnated with the radiation-sensitive substance in one or more selected parts of the layer. ### Claim 11 (depends on 1) The method of claim 1, wherein at least one of the layers comprises at least one pre-formed region intended to receive, contain, guide and/or control the flow of fluid during use of the device, the pre-formed region formed prior to forming the stack. ### Claim 12 (depends on 1) The method of claim 1, wherein the plurality of layers are made of the same material. ### Claim 13 (depends on 1) The method of claim 1, wherein the plurality of layers include at least one layer made of a first material and at least one layer made of a second material different to the first material. ### Claim 14 (depends on 1) The method of claim 1, wherein the plurality of layers include at least one isolation layer for blocking fluid flow from at least one neighbouring layer made of porous material. ### Claim 15 (canceled) ### Claim 16 (depends on 14) The method of claim 14, wherein the isolation layer comprises at least one hole for permitting fluid flow from the at least one neighbouring layer. ### Claim 17 (depends on 13) The method of claim 13, wherein the radiation is applied to change the radiation-sensitive substance from the first state to the second state in at least part of the at least one neighbouring layer to bond the isolation layer to the at least one neighbouring layer. ### Claim 18 (depends on 1) The method of claim 1, comprising applying solvent to remove parts of the radiation-sensitive substance which are in said other of the first state and the second state after the radiation has been applied. ### Claim at position 19 19-22. (canceled) ### Claim 23 (depends on 1) A fluid flow device made by the method of claim 1. ### Claim 24 (depends on 1) An apparatus configured to make a fluid flow device in accordance with the method of claim 1. ### Claim 25 A method for making a fluid flow device, comprising: providing a substrate of porous material, the substrate having a first surface and a second surface opposite the first surface; applying a beam of radiation onto the first surface of the substrate and causing relative translation between the substrate and the beam, to change a state of a radiation-sensitive substance impregnated in at least part of the substrate; and applying a beam of radiation onto the second surface of the substrate and causing relative translation between the substrate and the beam, to change a state of a radiation-sensitive substance impregnated in at least part of the substrate. ### Claim at position 23 26-41. (canceled) ### Claim 42 A method for making a fluid flow device, comprising: providing a substrate of porous material, where at least part of the substrate is impregnated with a radiation-sensitive substance in a first state; and applying radiation onto the substrate to change the radiation-sensitive substance from the first state to a second state, to form a backing layer of radiation-sensitive substance in the second state extending through part of the thickness of the substrate, wherein the substrate including the backing layer has greater mechanical strength than the porous material of the substrate. ### Claim at position 25 43-53. (canceled)