Sheet for uptake of a liquid sample

Abstract

Provided herein is a sheet (100) having a sheet first side (116) and an opposing sheet second side (118) wherein the sheet first side (116) is disposed with a plurality of adjacent capillary channels, channels (140, 140'), wherein exposure of one end of the sheet to a liquid induces formation in the sheet (100) of a tubular extending portion, TEP, (122, 122', 122") having a tubular structure (124, 124', 124") and having a length (120, 120', 120") that increases gradually over time in a flow direction (114) of the liquid along the plurality of channels (140, 140').

Description

[0001] Sheet for uptake of a liquid sample

[0002] Field

[0003] The invention is broadly in the field of liquid sampling, in particular, for testing liquid samples.

[0004] Background

[0005] Effective liquid sampling is crucial in many technological sectors including healthcare, foods and beverages, manufacturing, environmental. Typical steps of sampling involving inducing passage of a known volume of the liquid into a sampling device, reading of the results, often with a step of reacting the liquid with one or more reagents to test the liquid. The reagent is often attached to a wall of the sample device in order to reduce a number of processing steps. Ideally, tests need be fast, offer a large surface-to-volume ratio to achieve rapid and precise results, while consuming a small volume of liquid. The liquid sampling device is ideally light weight, is disposable to avoid cleaning and reproducibility problems, is low cost to manufacture, and has a minimum of mechanical parts.

[0006] It is an aim of the present invention to provide a sampling device that achieves the above- mentioned aims.

[0007] Summary

[0008] Provided herein is a sheet (100) having a sheet first side (116) and an opposing sheet second side (118) wherein

[0009] - only the sheet first side (116) is disposed with a plurality of adjacent and parallel capillary channels, channels (140, 140’);

[0010] - each and every channel (140, 140’) comprises a channel inlet end (142, 142’) at one longitudinal end of the channel (140, 140’) and a liquid inlet (144, 144’) at the channel inlet end (142, 142’) configured for inlet of the liquid;

[0011] - each and every channel liquid inlet (144, 144’) is aligned on the sheet first side along a start line (138), wherein the start line (138) is disposed at an immersion end (110) of the sheet;

[0012] - the sheet (100) has a first edge (102) and an opposing second edge (104), both edges (102, 104) parallel with the plurality of channels (140, 140’); - the sheet (100) comprises a native state prior to exposing the liquid inlets (144, 144’) to the liquid, and an activated state induced by exposure of the liquid inlets (144, 144’) to the liquid;

[0013] - in the native state of the sheet (100) each and every channel (140, 140’) is an open channel having a channel longitudinal open edge (158, 158’) along an entire longitudinal length of the channel (140, 140’);

[0014] - wherein the sheet (100) is configured such that in the active state, the exposure of the immersion end (110) of the sheet to the liquid induces the formation in the sheet (100) of a tubular portion, TP, (122, 122’, 122”) that is a portion of a length of the sheet (100) parallel to the plurality of channels (140, 140’), wherein the TP (122, 122’, 122”) has:

[0015] - a tubular structure (124, 124’, 124”) wherein:

[0016] - each and every of channel (140, 140’) of the plurality of channels is present and disposed on an internal surface (116a) of the tubular structure (124, 124’, 124”);

[0017] - each and every channel (140, 140’) of the plurality of channels (140, 140’) is closed thereby forming a separate longitudinal channel lumen (164, 164’) for each and every channel (140, 140’) in the TP (120, 120’, 120”); and

[0018] - the tubular structure is curved around a folding axis (109) disposed parallel to the plurality of channels (140, 140’) within the TP (122, 122’, 122”);

[0019] - a length (120, 120’, 120”) that increases gradually (over time) in a flow direction (114) of the liquid along the plurality of channels (140, 140’);

[0020] - wherein, in the gradually increasing length (120, 120’, 120”) of tubular structure (124, 124’, 124”), a portion of the opposing first edge (102) and a portion of the second opposing edge (104) of the sheet (100) co-operate together to form a length of closed edge (132) thereby forming the tubular structure (124, 124’, 124”) in the TP (122, 122’, 122”).

[0021] Further provided herein is a sheet (100) having a sheet first side (116) and an opposing sheet second side (118) wherein the sheet first side (116) is disposed with a plurality of adjacent capillary channels, channels (140, 140’), wherein exposure of one end of the sheet to a liquid induces formation in the sheet (100) of a tubular extending portion, TEP, (122, 122’, 122”) (also known as a tubular portion, TP, (122, 122’, 122”)) having a tubular structure (124, 124’, 124”) and having a length (120, 120’, 120”) that increases gradually over time in a flow direction (114) of the liquid along the plurality of channels (140, 140’).

[0022] According to a preferred aspect:

[0023] - the sheet (100) comprises a native state prior to exposing the liquid inlets (144, 144’) to the liquid, and an activated state induced by exposure of the liquid inlets (144, 144’) to the liquid; and

[0024] - in the native state of the sheet (100) each and every channel (140, 140’) is an open channel having a channel longitudinal open edge (158, 158’) along an entire longitudinal length of the channel (140, 140’).

[0025] Preferably, each and every channel (140, 140’, 140’”) of the plurality of channels is formed from a pair of adjacent longitudinal barrier bodies (150, 150’, 150’”) that flank and separate the channel.

[0026] Preferably, each and every channel (140, 140’, 140’”) of the plurality of channels is closed in the TP (122, 122’, 122”), the adjacent longitudinal barrier bodies (150, 150’, 150’”) that flank and separate each and every channel (140, 140’, 140’”) are in mutual contact, thereby closing the channel along a longitudinal closed edge, CLCE (162, 162’, 162’”) within the TP (122, 122’, 122”).

[0027] Preferably, a quantity of channels is N, and a dimension of the channels satisfy the condition: wherein: a is an average channel width (a) and b is an average channel height (b) for the sheet, where

[0028] - (a) is a channel width as determined from a transverse cross-sectional view of the sheet when the sheet is planar;

[0029] - (b) is a channel height as determined from a transverse cross-sectional view of the when the sheet is planar. The sheet (100) is preferably configured such that in the activated state:

[0030] - the tubular structure (124, 124’, 124”) of the TEP (120, 120’, 120”) contains a central tubular lumen (128) defined by a plurality of longitudinal barrier bodies (150, 150’), wherein the plurality of adjacent channels are mutually separated by the plurality of longitudinal barrier bodies (150, 150’) in the sheet (100).

[0031] The sheet (100) is preferably configured such that in the activated state each and every open channel (158, 158’) of the plurality of channels (140, 140’) is closed in TEP (120, 120’, 120”) thereby forming a longitudinal channel lumen (164, 164’) for each and every channel (140, 140’) in the TEP (120, 120’, 120”).

[0032] The sheet (100) is preferably configured such that in the activated state each and every channel longitudinal open edge (158, 158’) of the plurality of channels (140, 140’) is closed in TEP (120, 120’, 120”) thereby forming for each and every channel in the TEP (120, 120’, 120”):

[0033] - the closed channel; and

[0034] - the longitudinal channel lumen (164, 164’).

[0035] According to a preferred aspect the plurality of channels (140, 140’) is configured such that:

[0036] - a transport by the capillary action of the liquid in the plurality of channels (140, 140’) in the flow direction (114) generates an increase of the capillary force; and

[0037] - the increase of the capillary force creates the tubular extending portion, TEP, (122, 122’, 122”) of the sheet (100) containing tubular structure (124, 124’, 124”).

[0038] Preferably each and every channel of the plurality of channels (140, 140’) has a channel longitudinal wall (152, 154, 156) along a longitudinal length of the channel (140, 140’), and at least one of the channel longitudinal wall (152, 154, 156) is modified for testing of the liquid.

[0039] Preferably the at least one of the modified channel longitudinal wall (152, 154, 156) is not modified in an immersion zone (143, 143’) that is a longitudinal portion of the channel disposed at the immersion end (110) of the sheet (100). Provided herein is a method of sampling simultaneously multiple separate volumes of a liquid comprising:

[0040] - providing a sheet (100) as described herein;

[0041] - exposing the plurality of liquid inlets (144, 144’) to the liquid thereby inducing uptake of the liquid by capillary action into the plurality of channels (140, 140’) and formation of the tubular extending portion, TEP, (122, 122’, 122”); wherein as a result of the exposing, multiple separate volumes of the liquid are sampled within the plurality of adjacent channels (140, 140’).

[0042] Provided herein is a method for measuring viscosity of a liquid comprising:

[0043] - providing a sheet (100) as described herein;

[0044] - exposing the plurality of liquid inlets (144, 144’) to the liquid thereby inducing uptake of the liquid by capillary action into the plurality of channels (140, 140’) and formation of the tubular extending portion, TEP, (122, 122’, 122”);

[0045] - determining, from a time (vt) taken to reach a reference state which is a determinable state of the sheet (100) in the sheet activated state, the viscosity of the liquid.

[0046] A larger time (vt) is typically indicative of a higher liquid viscosity compared with a shorter time (vt).

[0047] Provided herein is a method for testing a liquid comprising:

[0048] - providing a sheet (100) as described herein, wherein one or more of the plurality of channels (140, 140’) contains a modified wall (152, 154, 156) for testing the liquid;

[0049] - exposing the plurality of liquid inlets (144, 144’) to the liquid thereby inducing uptake of the liquid by capillary action into the plurality of channels (140, 140’) and formation of the tubular extending portion, TEP, (122, 122’, 122”) such that the modified wall(s) comes into contact with the liquid; wherein as a result of the exposing and the modified wall(s) coming into contact with the liquid, the liquid is tested. Where the exposing of the liquid to one or more reactants of the modified wall(s) effects a change in the liquid in the one or more of the plurality of channel (140, 140’);

[0050] - method preferably further comprises:

[0051] - contacting the plurality of liquid inlets (144, 144’) of the TEP (122, 122’, 122”) with an absorbent substrate, thereby offloading the liquid contained in each channel of the plurality of channels (140, 140’) onto the absorbent substrate;

[0052] - applying one or more assays to the absorbent substrate.

[0053] Where the exposing of the liquid to one or more reactants of the modified wall(s) effects a change in the modified wall(s);

[0054] - the method preferably further comprises:

[0055] - uncurling the tubular extending portion, TEP, (122, 122’, 122”) such that the sheet (100) is flat; and

[0056] - reading the flat sheet using an optical reader.

[0057] Brief description of the drawings

[0058] The following description of the figures of specific embodiments of the invention is merely exemplary in nature and is not intended to limit the present teachings, their application or uses.

[0059] FIG. 1 illustrates a plan view of a sheet described herein.

[0060] FIG. 1A a transverse cross-sectional view of the sheet of FIG. 1 across a plane (A-A’).

[0061] Fig. 1 B is an enlargement of a portion of FIG. 1A.

[0062] Fig. 2 Panels A to D illustrate a formation of a tubular extending portion of the sheet as described herein.

[0063] FIG. 3 a transverse cross-sectional view of a sheet tubular extending portion.

[0064] FIG. 3A is an enlargement of a portion of FIG. 3.

[0065] FIG. 4 a transverse cross-sectional view of the sheet with dimensional indicators marked.

[0066] FIG. 5 shows a time series of photographs of a sheet as described herein after exposure to a liquid.

[0067] FIGs. 6 to 8 are different transverse cross-sectional views of the sheet, each having a different shape of longitudinal upper surface. FIG. 6 shows a linear longitudinal upper surface, FIG. 7 shows a plateaued longitudinal upper surface, FIG. 8 shows a rounded longitudinal upper surface. FIG. 9 shows a sheet of FIG. 1 disposed with an immersion zone

[0068] Description of embodiments

[0069] As used herein, the singular forms “a”, “an”, and “the” include both singular and plural referents unless the context clearly dictates otherwise.

[0070] The terms “comprising”, “comprises” and “comprised of’ as used herein are synonymous with “including”, “includes”, “containing”, or “contains”, and are inclusive or open-ended and do not exclude additional, non-recited members, elements or method steps. The terms also encompass “constituted of”, “consists in”, “consisting of”, and “consists of”, and also the terms “consisting essentially of’, “consisting essentially in” and “consists essentially of’, which enjoy well-established meanings in patent terminology.

[0071] The recitation of numerical ranges by endpoints includes all intervening values between the lower and upper endpoints, as well as the recited endpoints. Intervening values may be integers or, where applicable, fractions, i.e., more broadly any real numbers such as any rational numbers. This applies to numerical ranges irrespective of whether they are introduced by the expression “from... to...” or the expression “between... and...” or another expression. Any numerical range recited herein is intended to include all sub-ranges subsumed therein. For example, each sub-range between any stated value in a stated range and any other stated value in that stated range is also specifically disclosed. Each sub-range between any stated value in a stated range and either the lower endpoint or the upper endpoint of the stated range is also specifically disclosed. The stated value may be an isolated value or an endpoint of a range subsumed by or overlapping with the stated range. For example, for a stated range with lower endpoint L1 and upper endpoint U1 (i.e., stated range L1-LI1) and a stated sub-range nested within the stated range with lower endpoint L2 and upper endpoint U2 (i.e., stated subrange L2-LI2), also specifically disclosed are the subranges L1-L2, L1-LI2, L2-LI1 , and U2-LI1 .

[0072] The terms “about” or “approximately” as used herein when referring to a measurable value such as a parameter, an amount, a temporal duration, and the like, are meant to encompass variations of and from the specified value, such as variations of + / - 10% or less, preferably + / - 5% or less, more preferably + / -1% or less, and still more preferably + / -0.1 % or less of and from the specified value, insofar such variations are appropriate to perform in the disclosed invention. It is to be understood that the value to which the modifier “about” or “approximately” refers is itself also specifically, and preferably, disclosed.

[0073] Furthermore, the terms first, second, third and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequential or chronological order, unless specified. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other sequences than described or illustrated herein.

[0074] Whereas the terms “one or more” or “at least one”, such as one or more members or at least one member of a group of members, is clear per se, by means of further exemplification, the term encompasses inter alia a reference to any one of said members, or to any two or more of said members, such as, e.g., any >3, >4, >5, >6 or >7 etc. of said members, and up to all said members. In another example, “one or more” or “at least one” may refer to 1 , 2, 3, 4, 5, 6, 7 or more.

[0075] As used herein, the term “and / or” when used in a list of two or more items, means that any one of the listed items can be employed by itself or any combination of two or more of the listed items can be employed. For example, if a list is described as comprising group A, B, and / or C, the list can comprise A alone, B alone, C alone, A and B in combination, A and C in combination, B and C in combination, or A, B, and C in combination.

[0076] The discussion of the background to the invention herein is included to explain the context of the invention. This is not to be taken as an admission that any of the material referred to was published, known, or part of the common general knowledge in any country as of the priority date of any of the claims.

[0077] Throughout this disclosure, various publications, patents and published patent specifications are referenced by an identifying citation. All documents cited in the present specification are hereby incorporated by reference in their entirety. In particular, the teachings or sections of such documents herein specifically referred to are incorporated by reference. Unless otherwise defined, all terms used in disclosing the invention, including technical and scientific terms, have the meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. By means of further guidance, term definitions are included to better appreciate the teaching of the invention. When specific terms are defined in connection with a particular aspect of the invention or a particular embodiment of the invention, such connotation or meaning is meant to apply throughout this specification, i.e. , also in the context of other aspects or embodiments of the invention, unless otherwise defined.

[0078] In the following passages, different aspects or embodiments of the invention are defined in more detail. Each aspect or embodiment so defined may be combined with any other aspect(s) or embodiment(s) unless clearly indicated to the contrary. In particular, any feature indicated as being preferred or advantageous may be combined with any other feature or features indicated as being preferred or advantageous.

[0079] Reference throughout this specification to “one embodiment”, “an embodiment” means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment, but may. Furthermore, the particular features, structures or characteristics may be combined in any suitable manner, as would be apparent to a person skilled in the art from this disclosure, in one or more embodiments. Furthermore, while some embodiments described herein include some but not other features included in other embodiments, combinations of features of different embodiments are meant to be within the scope of the invention, and form different embodiments, as would be understood by those in the art. For example, in the appended claims, any of the claimed embodiments can be used in any combination.

[0080] Similarly, it should be appreciated that in the description of illustrative embodiments of the invention, various features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of one or more of the various inventive aspects. In the present description of the invention, reference is made to the accompanying drawings that form a part hereof, and in which are shown by way of illustration only of specific embodiments in which the invention may be practiced. Parenthesized or emboldened reference numerals affixed to respective elements merely exemplify the elements by way of example, with which it is not intended to limit the respective elements. Unless otherwise indicated, all figures and drawings in this document are not to scale and are chosen for the purpose of illustrating different embodiments of the invention. In particular the dimensions of the various components are depicted in illustrative terms only, and no relationship between the dimensions of the various components should be inferred from the drawings, unless so indicated.

[0081] By longitudinal as used in relation to an element means that a shape of the element has a longer dimension and a shorter dimensions A longitudinal axis is along the longer dimension. For example, a capillary channel is longitudinal, having a longer dimension along direction of flow.

[0082] By transverse as used herein in relation to a cross-section element means a cross-section across a plane perpendicular to the longitudinal direction or axis.

[0083] Provided is a sheet (100) having a sheet first side (or face) (116) and an opposing sheet second side (or face) (118). An exemplary sheet in a planar form is shown in FIGs. 1 and 1A.

[0084] The sheet first side (116) is disposed with a plurality of adjacent capillary channels (“channels”) (140, 140’).

[0085] Exposure of one end of the sheet to a liquid induces formation in the sheet (100) of a tubular portion, TP, (122, 122’, 122”). The term “tubular portion”, TP, (122, 122’, 122”) is also known as a “tubular extending portion”, TEP (122, 122’, 122”), and these terms are used interchangeably or synonymously herein. The TP, (122, 122’, 122”) has a tubular structure (124, 124’, 124”) and having a length (120, 120’, 120”) that increases gradually over time in a flow direction (114) of the liquid along the plurality of adjacent channels (140, 140’). Each and every channel (140, 140’) comprises a channel inlet end (142, 142’) at one longitudinal end of the channel (140, 140’). Each and every channel (140, 140’) comprises a channel opposing end (146, 146’) an opposing longitudinal end of the channel (140, 140’).

[0086] Each and every channel (140, 140’) comprises a liquid inlet (144, 144’) at the channel inlet end (142, 142’) configured for inlet of the liquid.

[0087] Each and every channel (140, 140’) comprises an open or blind end (148, 148’) at the channel opposing end (146, 146’).

[0088] Each and every channel (140, 140’) is configured for a liquid transport, by capillary action, of the liquid in a flow direction (114).

[0089] The flow direction is direction of flow from the liquid inlet (144, 144’) along the channel (140, 140’). More in particular, the flow direction (114) is a direction from the liquid inlet (144, 144’) towards the open or blind end (148, 148’). More in particular, the flow direction (114) is a direction from the channel inlet end (142, 142’). More in particular, the flow direction (114) is a direction from the channel inlet end (142, 142’) towards the channel opposing end (146, 146’).

[0090] The channels (140, 140’) of the plurality of channels (140, 140’) are disposed mutually parallel, wherein the plurality of adjacent channels are mutually separated by a plurality of longitudinal barrier bodies (150, 150’).

[0091] The sheet (100) comprises a native state prior to exposing the liquid inlets (144, 144’) to the liquid and an activated state induced by exposure of the liquid inlets (144, 144’) to the liquid. Examples of the sheet in the activated state are shown in FIG. 2 Panels A to D and in FIGs. 3 and 3A.

[0092] In the native state of the sheet (100) each and every channel (140, 140’) is an open channel having a channel longitudinal open edge (158, 158’) along (an entire) longitudinal length of the channel. The sheet (100) is configured such that in the activated state the tubular structure (124, 124’, 124”) of the TP (120, 120’, 120”) contains a central tubular lumen (128) defined by a plurality of longitudinal barrier bodies (150, 150’), wherein the plurality of adjacent channels are mutually separated by the plurality of longitudinal barrier bodies (150, 150’) in the sheet (100).

[0093] The sheet (100) is further configured such that in the activated state each and every open channel (158, 158’) of the plurality of channels (140, 140’) is (becomes) closed in TP (120, 120’, 120”) (only) thereby forming a longitudinal channel lumen (164, 164’) for each and every channel (140, 140’) in the TP (120, 120’, 120”). Each and every longitudinal channel lumen (164, 164’) is separate. By separated, is meant that adjacent every longitudinal channel lumen (164, 164’) is not connected.

[0094] The sheet (100) is further configured such that in the activated state each and every channel longitudinal open edge (158, 158’) of the plurality of channels (140, 140’) is (becomes) closed in TP (120, 120’, 120”) (only) thereby forming for each and every channel in the TP (120, 120’, 120”):

[0095] - the closed channel; and

[0096] - the longitudinal channel lumen (164, 164’).

[0097] In other words, the sheet (100) is configured such that in the activated state:

[0098] - the tubular portion, TP, (122, 122’, 122”) acquires the tubular structure (124, 124’, 124”) and the length (120, 120’, 120”) of the TP (122, 122’, 122”) increases gradually over time in the flow direction (114);

[0099] - wherein in the TP (only):

[0100] - the tubular structure (124, 124’, 124”) contains a (closed) central tubular lumen (128) defined by the plurality of longitudinal barrier bodies (150, 150’);

[0101] - each and every open channel (158, 158’) of the plurality of channels (140, 140’) is (becomes) closed, wherein:

[0102] - each and every longitudinal open edge (158, 158’) of the plurality of channels (140, 140’) of the tubular structure (124, 124’, 124”) in the TP (120, 120’, 120”) is (becomes) a longitudinal closed edge (162, 162’), thereby forming a longitudinal channel lumen (164, 164’) for each and every channel (140, 140’)

[0103] The ability of a channel, as a result of liquid transport, to transition gradually longitudinally from an open to a closed state allows a large and rapid liquid uptake in a protective tube. In the open state each channel has a longitudinal open edge (158, 158’) where liquid rise is more rapid because of an absence of impeding friction caused by a lack of wall where the longitudinal open edge (158, 158’) is present. The longitudinal open edge (158, 158’) only closes at a point after the liquid has passes through that point. Rapid and voluminous liquid uptake is desirable especially in warm climates where evaporation of small volume samples is problematic.

[0104] The volume of the channel in the open state is larger than in the close state, allow a larger volume of liquid to be transported in a shorter period of time.

[0105] Further, the progressively increasing longitudinal closed edge (162, 162’, 162””) of each channel provides resistance to evaporation of the liquid as the channel transforms to the closed state. Reducing evaporation of the sample is particularly important where the liquid contains an organic liquid.

[0106] Further, in the closed state, each closed channel protects the sample from mechanical shock. Where the sheet is subject to mechanical shock (e.g. is transported or is dropped), cross-contamination between channels or loss of liquid from a channel is minimised.

[0107] Since the sheet has potential to be planar, multiple sheets can be stacked so occupying a minimal volume compared with cylindrical shapes typical of conventional devices for liquid uptake. Reduction of package space reduces transport and storage costs. Additionally, a planar sheet is less fragile compared with cylindrical structures of the same wall thickness. Less protective packaging is needed for a two-dimensional form compared with the three- dimensional form of typical cylindrical devices. There is also a weight reduction.

[0108] Unloading the sample in a tubular configuration by contacting the liquid inlets (144,144') with a sheet of absorbent substrate (e.g. paper) results in less inter-channel cross-contamination compared to unloading from the planar state. With the tubular shape, the liquid is absorbed radially outward, and the distance between the orthoradial centres of mass of the liquid from adjacent channels increases as the radial distance expands. In contrast, in the planar configuration, the lateral distance between the centres of mass of the absorbed liquid from adjacent areas remains constant. Consequently, since the liquid spreads laterally over time during absorption, the tubular geometry reduces cross-contamination more effectively than the planar geometry.

[0109] The sheet (100) has a sheet native state wherein the sheet (100) which has not been exposed to the liquid. In particular, the liquid inlets (144, 144’) have not been exposed to the liquid. The sheet in the sheet native state is typically dry. The sheet in the sheet native state is typically planar and / or is able to adopt and maintain a planar form without application of forces needed to overcome the activated state.

[0110] In the sheet native state, each and every channel (140, 140’) of the plurality of channels is open along an entire longitudinal length of the channel. In the sheet native state, each and every channel (140, 140’) of the plurality of channels comprises a channel longitudinal open edge CLOE (158, 158’) along an entire longitudinal length of the channel. The CLOE (158, 158’) is formed from adjacent longitudinal barrier bodies (150, 150’) that are mutually apart. More in particular, the CLOE (158, 158’) of a channel is formed from adjacent longitudinal barrier bodies (150, 150’) that flank (and separate) the channel and which are mutually apart. More in particular, the upper surfaces (faces) of the adjacent longitudinal barrier bodies (150, 150’) are mutually apart (and mutually non-contacting). Each longitudinal barrier body (150, 150’) is a protruding longitudinal strip, in particular protruding in an upper direction from a surface of the sheet first side (116).

[0111] The sheet in the native state planar form has two opposing edges - first and second edges (102, 104) - that are opposing edges of the sheet (100) parallel with the plurality of channels (140, 140’). The first and second edges (102, 104) are preferably each perpendicular to the folding axis (109). The two opposing first and second edges (102, 104) are each preferably linear. The two opposing first and second edges (102, 104) are each preferably mutually parallel. The sheet (100) in the native state planar form has two opposing edges - third and fourth edges (106, 108) - that are other opposing edges of the sheet (100), and connect the first and second edges (102, 104). The third and fourth edges (106, 108) are preferably each perpendicular to the plurality of channels (140, 140’). The third and fourth edges (106, 108) are preferably each perpendicular to the folding axis (109). The third and fourth edges (106, 108) are each preferably linear. The third and fourth edges (106, 108) are each preferably mutually parallel.

[0112] The sheet (100) in the native state planar form may be rectangular (square or oblong). The edges of the rectangular are the first, second, third and fourth edges. In the oblong sheet (100), the plurality of channels (140, 140’) is disposed aligned with the first and second edges (102, 104). The sheet (100) has a folding axis (109) that an axis is parallel to the plurality of channels (140, 140’). The folding axis (109) is an axis around which the sheet folds or curls into a tubular structure in the activated state. The tubular structure (124, 124’, 124”) is curved around the folding axis (109) disposed parallel to the plurality of channels (140, 140’) within the TP (122, 122’, 122”). The folding axis (109) can be identified in both the native state and activated state.

[0113] The sheet (100) in the native state has a sheet first side (116) and an opposing sheet second side (118). An exemplary sheet is shown in FIGs. 1 (Plan view), 1A (transverse cross section), and 1 B (detail of transverse cross section).

[0114] The sheet first side (116) is disposed with the plurality of channels (140, 140’). The second side (118) is preferably devoid of capillary channels. Preferably only the sheet first side (116) is disposed with the plurality of channels (140, 140’).

[0115] The sheet (100) in the native state has an upper direction which is a direction of the sheet starting from the sheet first side (116) and moving upwards as if the sheet second side (118) was placed on a level surface. The sheet (100) in the native state has a lower direction which is a direction of the sheet starting from the sheet second side (118) and moving downwards as if the sheet second side (118) was placed on a level surface. It is appreciated that the terms upper direction and lower direction are relative that are not dependent the sheet orientation. For instance, a first side of the sheet would be regarded pointing in an upper direction regardless of the orientation of the sheet.

[0116] The sheet (100) has an immersion end (110) and an opposing dry end (112). The immersion end (110) is at one end of the sheet towards the third edge (106). The immersion end is configured for immersion (of the entire immersion end) into a liquid, preferably into one and the same liquid for all the channels. The dry end (112) is an opposing end to the immersion end (110) of the sheet towards the fourth edge (108).

[0117] Each and every channel liquid inlet (144, 144’) is aligned on the sheet first side along a start line (138), wherein the start line (138) is disposed at the immersion end (110) of the sheet. Exposure of the immersion one end (110) of the sheet to the liquid induces formation in the sheet (100) of the tubular portion, TP, (122, 122’, 122”). The start line (138) is preferably a linear line when the sheet (100) is planar. The start line (138) may or may not be separately marked as a line. The start line (138) may be along the sheet third edge (106).

[0118] Each and every channel open or blind end (148, 148’) is aligned on the sheet first side along a finish line (139), wherein the finish line is disposed at a dry end (112) of the sheet. The finish line (139) is preferably a linear line when the sheet (100) is planar. The finish line (139) may or may not be separately marked as a line. The finish line (139) may be along the sheet fourth edge (108).

[0119] The sheet (100) has a sheet activated state which is induced by exposing (only) the liquid inlets (144, 144’) to the liquid.

[0120] The sheet in the sheet activated state has a momentary curled state, prior to formation of a tubular portion, TP (122, 122’, 122”). In the curled state, the sheet (100) starts to curl around the folding axis (109). In the curled state, sheet first side (116) is on an inner side (116b) of the curl. The inner side (116b) of the curl faces the folding axis. In the curled state, capillary channels, channels (140, 140’) are disposed on an inner side (116b) of the curl. No portion of the opposing first and second edges (102, 104) of the sheet co-operate together to form a closed edge. No portion of sheet forms a tube. An exemplary curled state is shown in FIG. 2, Panel A. At the immersion end (110) of the sheet (100), the curling is to a greater extent compared with at the free end (112) of the sheet. When a distance of liquid transported by capillary action into the channels reaches a critical imbibition distance, the tubular portion forms (122, FIG. 2, Panel B).

[0121] The sheet in the sheet activated state has a tubular portion, TP (122, 122’, 122”).

[0122] A TP, (122, 122’, 122”) is a portion of a length of the sheet (100) parallel to the plurality of channels (140, 140’). In particular, a tubular portion, TP (122, 122’, 122”), is a portion of a length of the sheet (100) parallel the folding axis (109) in which the sheet (100) adopts a tubular structure (124, 124’, 124”). The tubular structure is typically understood as a tube or is tube-shaped. The TP (122, 122’, 122”) at one end (126, 126’, 126”) includes or is delimited by the liquid inlets (144, 144’). The TP (122, 122’, 122”) at an opposing end (127, 127’, 127”) is delimited by a breach of the tubular structure ( / .e. the tube wall is no longer circumferentially intact, by virtue of a channel longitudinal open edge CLOE (158, 158’) (see elsewhere herein)). The TP (122, 122’, 122”) has an (longitudinal) axis parallel to folding axis (109).

[0123] In the tubular portion, TP (122, 122’, 122”), the opposing first and second edges (102, 104) of the sheet co-operate together to form a closed edge (132). In the tubular portion, TP (122, 122’, 122”), the opposing first and second edges (102, 104) of the sheet co-operate together to form the closed edge (132) and form a new channel (140’”) (see elsewhere herein).

[0124] In the TP (122, 122’, 122”), the sheet first side (116) is (only) on an interior (116a) of, or forms (only) an internal surface (116a) of or is (only) inside (116a) the tubular structure (124, 124’, 124”). The interior (116a) of, or internal surface (116a) of, or inside (116a) the tubular structure refers to a region or volume enclosed by the sheet second side in the TP. In the TP (122, 122’, 122”), the capillary channels (140, 140’) are disposed (only) on an interior (116a) of, or (only) on an internal surface (116a) of, or (only) inside (116a) the tubular structure (124, 124’, 124”).

[0125] In the tubular portion, TP (122, 122’, 122”), the opposing first and second edges (102, 104) of the sheet co-operate together to form a closed edge (132). The closed edge has a length equal to a length of the TP (122, 122’, 122”). The closed edge (132) is only in the TP (122, 122’, 122”). In the tubular portion, TP (122, 122’, 122”), the opposing first and second edges (102, 104) of the sheet co-operate together to form the tubular structure (124, 124’, 124”) (only) in the TP (122, 122’, 122”). The tubular structure (124, 124’, 124”) has a length equal to a length of the TP (122, 122’, 122”). The tubular structure (124, 124’, 124”) is only in the TP (122, 122’, 122”).

[0126] A length of the TP, (122, 122’, 122”) increases gradually over time in the flow direction (114) after the exposing (only) of the liquid inlets (144, 144’) to the liquid. The length of the TP (122, 122’, 122”) increases as a function of the capillary length (distance along which the liquid has travelled in the channel). The gradual increase in the TP, (122, 122’, 122”) may or may not be at a constant rate; typically it is not at a constant rate. For instance, the rate of increase in TP length is typically faster at the start of the exposure to the liquid, and typically slows down after the TP > 30% of the length of the channels. The variable rate of increase, in particular a presence of a slower phase, allows the time (vt) taken to form a reference state to be used as a measure of viscosity (see elsewhere herein).

[0127] The length of the TP, (122, 122’, 122”) increases gradually over time in the flow direction (114) after the exposing (only) of the liquid inlets (144, 144’) to the liquid. In gradually increasing length (120, 120’, 120”) of tubular structure (124, 124’, 124”), a (gradually increasing) portion of the opposing first edge (102) and a (gradually increasing) portion of the second opposing edge (104) of the sheet (100) co-operate together to form a (gradually increasing (length of)) closed edge (132) thereby forming the tubular structure (124, 124’, 124”) (only) in the TP (122, 122’, 122”).

[0128] The sheet (100) in the TP (122, 122’, 122”) has a tubular structure (124, 124’, 124”), meaning that a transverse cross section of the sheet in the TP contains a central lumen (128) having a continuous lumen wall that encloses the central lumen (128). By tubular structure, it is meant a closed tube having a continuous lumen wall enclosing the central lumen (128), wherein the continuous lumen wall is circumferentially intact by virtue of a plurality of channel longitudinal closed edges, CLCE (162, 162’, 162’”) (see elsewhere herein). By tubular structure, it is meant a closed tube having an exterior tube wall is circumferentially intact by virtue of the opposing first and second edges (102, 104) of the sheet co-operating together to form the closed edge (132). The tubular structure (124, 124’, 124”) may or may not have a hollow cylindrical form; other prism shapes are foreseen such as an oval profile prism. The sheet (100) in the sheet activated state has a sheet final state in which TP (122, 122’, 122”) has stopped extending. The sheet final state is a stable state - namely the tubular shape of the sheet (100) is stably maintained for a period of time (typically hours or days). The sheet can remain in the sheet final state indefinitely if the immersion end remains in contact with the liquid. The activated sheet in the sheet final state may or may not be fully tubular along its length parallel to the folding axis (109). Where the activated sheet in the sheet final state is fully tubular along its length parallel to the folding axis (109), it is appreciated that the TP (122, 122’, 122”) at the opposing end (127) is delimited by the end of the sheet (100). An exemplary sheet final state is shown in FIG. 2 Panel D.

[0129] The sheet (100) in the sheet activated state also has a non-tubular portion, NTP, (129, 129’) whose length decreases gradually over time in the flow direction (114) after the exposing (only) of the liquid inlets (144, 144’) to the liquid. The non-tubular portion, NTP, a portion of a length of the sheet (100) along the folding axis (109) that is a remainder of the sheet (100) after taking into account the TP. Exemplary NTPs, (129, 129’) are shown in FIG. 2 Panels B and C.

[0130] The sheet in the NTP has a non-tubular structure, meaning that it does not have a central lumen and does not have continuous wall that encloses the central lumen. The sheet in the NTP has a non-tubular structure meaning that the tube wall is no longer circumferentially intact by virtue of a channel longitudinal open edge CLOE (158, 158’) (see elsewhere herein). The sheet in the NTP has a non-tubular structure meaning that the tube wall is no longer circumferentially intact by virtue of the opposing first and second edges (102, 104) of the sheet co-operating together to form the closed edge (132).

[0131] The sheet in the NTP may be planar or curled around the folding axis (109) of the sheet (100).

[0132] The sheet (100) may be made from any suitable material having requisite flexibility as described elsewhere herein. Examples of suitable materials include, for instance, silicone rubber, natural latex, polyurethane, and the like.

[0133] The material is preferably an elastic material (spring-like), meaning that it returns to its original shape after the capillary forces which cause a deformation (into a curl or tube) are removed. In particular, the elastic material is a material which can be deformed (activated state e.g. curled or tubular state) from its original shape (native state, e.g. planar), will return to the original shape when the capillary forces are removed, for instance when the liquid is discharged from the sheet. The elastic material may or may not be compressible. The elastic material may or may not be stretchable.

[0134] The material may be non-elastic, meaning it will not return to its original shape after the capillary forces which cause a deformation (into a curl or tube) are removed. It may return to its original shape by the application of an external force (e.g. to uncurl the activated state).

[0135] If the material of the sheet is prone to swelling, the sheet may be pre-swollen by soaking and then excess liquid is then wiped off - usually in a planar form.

[0136] Where the sheet is made from silicone rubber and the liquid is aqueous, silicone rubber may be pre-treated to increase its wettability. For instance, the sheet may be plasma-treated, followed by a treatment with 2% albumin solution, and then dried - usually in a planar form (e.g. by heating).

[0137] The sheet may be manufactured according to any known method. For instance, the sheet made my made by moulding, 3D printing, spin-coating on a corrugated surface, injection moulding, hot embossing, laser ablation, micro milling, photo-lithography, soft-lithography, and the like.

[0138] Each and every channel (140, 140’) of the plurality of channels in the sheet is configured for a liquid transport, by capillary action, of the liquid in a flow direction (114). The capillary action as understood in the art is observed when the liquid wets the sheet. As is understood by the person skilled in the art, liquid transport by capillary action into a channel (140, 140’) arises when a channel width (a) is less than the lcwhich is a length over which gravitational effects are stronger than capillary effects, wherein:

[0139] - lc , with y the surface tension of the liquid, p its density and g the gravitational acceleration); As mentioned elsewhere herein, the activated state generates a central tubular lumen (128).

[0140] Capillary rise into the central tubular lumen (128) arises when the condition of Eq. 1 is met bd / a < lc[Eq. 1],

[0141] Wherein:

[0142] - p is the liquid density;

[0143] - y is surface tension of the liquid;

[0144] - g is gravitational acceleration;

[0145] - a is a channel width as determined from a transverse cross-sectional view of the sheet (see for instance FIG. 4). More in particular it is an average of each shortest distance between two adjacent longitudinal barrier bodies (150, 150’) that flank (and separate) each channel (140, 140’) when the sheet is planar;

[0146] - b is a channel height as determined from a transverse cross-sectional view of the sheet (see for instance FIG. 4). More in particular it is an average shortest height of the longitudinal barrier bodies (150, 150’) measured from a within each channel when the sheet is planar. The height in particular is an average shortest height of a channel longitude side wall (152, 154) of the channel; and

[0147] - d is a longitudinal barrier body (150, 150’) width as determined from a transverse cross- sectional view of the sheet (see for instance FIG. 4). More in particular it is an average smallest width of the longitudinal barrier bodies (150, 150’) present within the sheet when the sheet is planar.

[0148] The sheet (100) is configured such in the activated state a portion of the sheet, a tubular portion, TP, (122, 122’, 122”) acquires the tubular structure (124, 124’, 124”). As is understood by the person skilled in the art, the sheet (100) is sufficiently flexible such that a moving front of elastocapillarity forces overcomes a resistance to curling in the sheet.

[0149] A sufficiently flexible sheet has the following properties, namely when the condition of Eq. 2 is fulfilled:

[0150] . 8 B a2F . , 2d , _ - - , / a\2„

[0151] A = - 1 + — + 0.556 - < 1, [Eq. 2]

[0152] 27 Yb3lc[ b \bjL J wherein:

[0153] B = - — is a bending modulus of the material used in the sheet;

[0154] 12 (1— v2)a

[0155] - E is the Young modulus of the material used in the sheet;

[0156] - L the length of the sheet;

[0157] - v is Poisson’s ratio;

[0158] - a is an average channel width (a) as mentioned above;

[0159] - b is an average channel height (b) as mentioned above;

[0160] - c is an average sheet thickness (c) for the sheet as determined from a transverse cross- sectional view of the sheet (see for instance FIG. 4). More in particular it is an average thickness of the sheet measured from a within each channel (excluding the longitudinal barrier bodies (150, 150’)) when the sheet is planar; lcis the typical length over which gravitational effects are stronger than capillary effects as mentioned above;

[0161] The above formulas apply to a vertical sheet.

[0162] Each and every channel (140, 140’, 140’”) of the plurality of channels in the TP (122, 122’, 122”) is closed. Each and every channel (140, 140’, 140’”) of the plurality of channels in the TP (122, 122’, 122”) comprises a channel longitudinal closed edge, CLCE (162, 162’, 162’”) along a longitudinal length of the channel where side walls of adjacent channels mutually meet and contact. More in particular, the CLCE (162, 162’, 162’”) of a channel is formed from adjacent longitudinal barrier bodies (150, 150’) that flank the channel and whose longitudinal side walls (152, 154) mutually meet and contact. To form a CLCE (162, 162’, 162’”) for each and every channel, the skilled person would understand how to configure a dimension of the channels. For instance, a number (N) of channels (140, 140’, 140’”) must satisfy the condition of Eq. 3.

[0163] 2 T b N = — (Eq. 3) a wherein: a is an average channel width (a) and b is an average channel height (b) as mentioned earlier. Each and every channel of the plurality of channels preferably has the same channel width (±10%). However, it is within the scope of the invention that at least two channels of the plurality of channels has a different channel width.

[0164] Each and every channel of the plurality of channels preferably has the same channel height (±10%).

[0165] Each and every channel of the plurality of channels preferably has the same channel length (±10%). However, it is within the scope of the invention that at least two channels of the plurality of channels has a different channel length.

[0166] Each and every longitudinal barrier body (150, 150’) preferably has the same width (±10%). However, it is within the scope of the invention that at least two longitudinal barrier body (150, 150’) of the plurality of longitudinal barrier body (150, 150’) has a different width.

[0167] Eq. 3 herein defines a quantity of pillars required to form a CLCE (162, 162’, 162’”) for each and every channel to forming the TP (122, 122’, 122”) regardless of the shape of the upper portion (160). By adjusting a geometry of the upper portions (160), a geometry of a transverse cross-section of the central tubular lumen (128) can be adjusted. The maximum span (Spanmax) of the central tubular lumen (128) (in transverse cross-section) is given by Eq. 4. Spanmax = bd / a [Eq. 4] where a is an average channel width (a) and b is an average channel height (b) of the sheet as mentioned earlier, and d is an average width of the barrier bodies (FIG. 4) in the sheet.

[0168] Intermediate span values can be achieved by using upper portions (160) of different upper width (e.g. FIG. 7). In this case, the span (Span) of the central tubular lumen (128) is given by Eq. 5:

[0169] Span = bd' / a [Eq. 5] where d’ represents an average upper width of the upper portions (160) in the sheet. The upper width of an upper portions (160) is a width of an upper-most end of an upper portion (160) (see, for instance, FIG. 7).

[0170] Each and every channel of the plurality of channels (140, 140’) is longitudinal.

[0171] Each and every channel of the plurality of channels (140, 140’) is preferably linear. Each and every channel of the plurality of channels (140, 140’) preferably linear and has a longitudinal axis.

[0172] Each and every channel of the plurality of channels (140, 140’) preferably has the same dimensions.

[0173] Each and every channel of the plurality of channels (140, 140’) has a channel longitudinal wall (152, 154, 156) along a longitudinal length of the channel. The channel longitudinal wall (152, 154, 156) is between the liquid inlet (144, 144’) and the open or blind end (148, 148’). The channel longitudinal wall (152, 154, 156) is formed from a body of the sheet (100).

[0174] The channel longitude wall (152, 154, 156) has two channel longitude side walls (152, 154) and a channel longitude base wall (156). The channel longitude base wall (156) connects the two channel longitude side walls (152, 154). The two channel longitude side walls (152, 154) are each part of adjacent longitudinal barrier bodies (150, 150’, 150”, 150’”).

[0175] Each and every channel (140, 140’, 140’”) of the plurality of channels in the TP (122, 122’, 122”) (and hence in the tubular structure (124, 124’, 124”)) is closed. Each and every channel (140, 140’, 140’”) of the plurality of channels in the TP (122, 122’, 122”) comprises a channel longitudinal closed edge, CLCE (162, 162’, 162’”) along a longitudinal length of the channel devoid of side (upper) wall. The CLCE (162, 162’, 162’”) is formed from adjacent longitudinal barrier bodies (150, 150’, 150”, 150’”) that are in mutual contact. More in particular, the CLCE (162, 162’, 162’”) of a channel is formed from adjacent longitudinal barrier bodies (150, 150’, 150”, 150’”) that flank the channel and which are in mutual contact. In particular the CLCE (162, 162’) of a channel is formed from longitudinal upper surfaces (faces) (160, 160’, 160’”) of the adjacent longitudinal barrier bodies (150, 150’, 150”, 150’”) that flank the channel and which are in mutual contact.

[0176] Each and every channel (140, 140’, 140’”) of the plurality of channels of the TP (122, 122’, 122”) is closed. By closed in relation to a channel, it is meant that the two longitudinal barrier bodies (150, 150’, 150’”) that longitudinally flank the channel relocate in the TP to form the CLCE (162, 162’, 162’”), thereby forming a lumen, a longitudinal channel lumen (164, 164’, 164’”). The longitudinal channel lumen (164, 164’, 164’”) is bound by the channel longitudinal wall (152, 154, 156) closed along channel longitudinal closed edge, CLCE (162, 162’, 162’”). By “closed”, it is meant that a transverse profile of the longitudinal channel lumen (164, 164’, 164”’) shows said lumen bound by a closed loop (see for instance FIGs. 3 and 3A). By “closed”, it is meant that a transverse profile of the longitudinal channel lumen (164, 164’, 164’”) shows said lumen bound by a continuous wall. The continuous wall is the channel longitudinal wall (152, 154, 156).

[0177] The CLCE (162, 162’, 162’”) and longitudinal channel lumen (164, 164’, 164’”) are each limited to a longitudinal portion of the channel in the TP (122, 122’, 122”). Neither the CLCE (162, 162’, 162’”) nor the longitudinal channel lumen (164, 164’, 164’”) are present in the longitudinal portion of the channel in the NTP (129, 129’).

[0178] It is appreciated that one of the closed channels of the plurality of channels of the TP (122, 122’, 122”) is a new channel (140’”) is formed by the two longitudinal barrier bodies (150, 150’”) disposed along or next to the opposing longitudinal edges (102, 104) of the sheet (100) that become adjacent as a result of the sheet adopting the tubular structure in the TP (122, 122’, 122”) and opposing longitudinal edges (102, 104) of the sheet co-operating together (mutually contact) to form the closed edge (132).

[0179] It is appreciated one of the CLCE of the TP (122, 122’, 122”) is a new CLCE (162’”), formed by the two longitudinal barrier bodies (150, 150’”) disposed along or next to the opposing longitudinal edges (102, 104) of the sheet (100) is formed from longitudinal barrier bodies (150, 150’”) that become adjacent, flank the new channel (140’”) and become in mutual contact as a result of the sheet adopting the tubular structure in the TP (122, 122’, 122”) and opposing longitudinal edges (102, 104) co-operating together (mutually contact) to form the closed edge (132).

[0180] It is appreciated that one of longitudinal channel lumens is a new longitudinal channel lumen (164’”) formed by the two longitudinal barrier bodies (150, 150’”) disposed along or next to the opposing longitudinal edges (102, 104) of the sheet (100) that become adjacent, flank the new channel (140’”) and form the new longitudinal channel lumen (164’”) as a result of the sheet adopting the tubular structure in the TP (122, 122’, 122”) and opposing longitudinal edges (102, 104) co-operating together (mutually contact) to form the closed edge (132). A majority of, preferably each and every channel (140, 140’) of the plurality of channels in the NTP, (129, 129’) comprises a channel longitudinal open edge CLOE (158, 158’) along a longitudinal length of the channel. As mentioned earlier herein, a CLOE (158, 158’) is formed from adjacent longitudinal barrier bodies (150, 150’) that are mutually apart. More in particular, the CLOE (158, 158’) of a channel is formed from adjacent longitudinal barrier bodies (150, 150’) that flank the channel and which are mutually apart.

[0181] Each and every channel (140, 140’) of the plurality of channels of the NTP (129, 129’) is open. By open in relation to a channel, it is meant that the two longitudinal barrier bodies (150, 150’) that longitudinally flank the channel remain separated (non-contacting).

[0182] By “open”, it is meant that a transverse profile of the open channel (140, 140’) contains a fill area (141), bound by the channel longitudinal wall (152, 154, 156) and the channel longitudinal open edge, CLOE (158, 158’) in transverse profile. See for instance FIG. 1B.

[0183] More in particular, by “open”, it is meant that a transverse profile of the open channel (140, 140’) contains a fill area (141) bound by a discontinuous wall. The discontinuous wall is the channel longitudinal wall (152, 154, 156) and the corresponding channel longitudinal open edge, CLOE (158, 158’) in transverse profile.

[0184] The CLOE (158, 158’) and longitudinal channel open lumen (158, 158’) are each limited to a longitudinal portion of the channel in the NTP (129, 129’) in the sheet activated state. Neither the CLOE (158, 158’) nor the longitudinal channel open lumen (158, 158’) are present in the longitudinal portion of the channel in the NTP (129, 129’).

[0185] Each and every longitudinal open edge (158, 158’) of the plurality of channels (140, 140’) of the tubular structure (124, 124’, 124”) of the TP (120, 120’, 120”) is transformed into a longitudinal closed edge (162, 162’, 162’”).

[0186] Each and every channel (140, 140’) of the plurality of channels (140, 140’) of the tubular structure (124, 124’, 124”) of the TP (120, 120’, 120”) is transformed by into a longitudinal channel lumen (164, 164’, 164’”). A length of the TP, (122, 122’, 122”) increases gradually over time in the flow direction (114) after the exposing (only) of the liquid inlets (144, 144’) to the liquid. In the TP (122, 122’, 122”) the sheet (100) adopts the tubular structure (124, 124’, 124”). In the gradually increasing length (120, 120’, 120”) of tubular structure (124, 124’, 124”), each and every channel (140, 140’) becomes closed (only in the TP (122, 122’, 122”)). In the gradually increasing length (120, 120’, 120”) of tubular structure (124, 124’, 124”), each and every channel (140, 140’) becomes a longitudinal channel lumen (164, 164’, 164’”) (only in the TP (122, 122’, 122”)).

[0187] Each and every longitudinal barrier body (150, 150’, 150”, 150’”) is longitudinal.

[0188] Each and every longitudinal barrier body (150, 150’, 150”, 150’”) is preferably linear.

[0189] Each and every longitudinal barrier body (150, 150’, 150”, 150’”) is preferably linear and has a longitudinal axis.

[0190] Each and every longitudinal barrier body (150, 150’, 150”, 150’”) is disposed parallel to an adjacent channel (140, 140’).

[0191] Each and every longitudinal barrier body (150, 150’, 150”, 150’”) is preferably disposed parallel to the two opposing first and second edges (102, 104).

[0192] Each and every longitudinal barrier body (150, 150’, 150”, 150’”) may have the same dimensions.

[0193] Each and every longitudinal barrier body (150, 150’, 150”, 150’”) comprises a pair of longitudinal side walls (152, 154), LBB side walls (152, 154). Each LBB side wall from adjacent longitudinal barrier bodies (150, 150’, 150”, 150’”) forms a respective channel side longitudinal wall (152, 154).

[0194] Each and every longitudinal barrier body (150, 150’, 150”, 150’”) comprises a longitudinal upper surface (160, 160’, 160’”). The longitudinal upper surface (160, 160’, 160’”) of the longitudinal barrier bodies (150, 150’, 150”, 150’”) joins the pair of LBB side walls within a longitudinal barrier body (150, 150’, 150”, 150’”).

[0195] The longitudinal upper surface (160, 160’, 160’”), may have transverse profile ( / .e. a profile when viewed in transverse cross-section of the longitudinal barrier body (150, 150’, 150”, 150”’)) of any suitable shape, such as a linear shape (e.g. FIG. 6), a curved shape (e.g. FIG. 8)), two bends (may be trapezoid shape (e.g. FIG. 7)). A suitable shape is a shape that, when co-operating with adjacent longitudinal upper surfaces (160, 160’, 160’”) forms the closed channel in the TP.

[0196] The sheet (100) in the TP (120, 120’, 120”) is disposed with a central tubular lumen (128). The central tubular lumen (128) is a longitudinally closed lumen. The central tubular lumen (128) is limited to the TP (120, 120’, 120”). The central tubular lumen (128) is formed from the longitudinal barrier bodies (150, 150’, 150’”). More in particular, the central tubular lumen (128) is formed from the longitudinal barrier body (150, 150’, 150’”) longitudinal upper surfaces (faces) (160, 160’, 160’”), which in the TP (120, 120’, 120”) are joined by contact in series to form a closed loop.

[0197] The central tubular lumen (128) may or may not be suitable for liquid transport by capillary action. The suitability for liquid transport by capillary action is determined by a transverse cross-sectional size of the central tubular lumen (128). In particular, capillary rise into the central tubular lumen (128) arises when the condition of Eq.1 is met.

[0198] Where the central tubular lumen (128) is suitable for fluid transport by capillary action, it provides additional capacity, and thereby the sheet able to uptake additional liquid volume. Further, the central tubular lumen (128) is a closed lumen thereby providing resistance to evaporation and shock.

[0199] The liquid may be any, for instance, aqueous or non-aqueous (organic) or a mixture of aqueous or non-aqueous liquids. Examples of non-aqueous liquids include, for instance silicone oil, mineral oil, ethanol, acetone, or a mixture of these.

[0200] The liquid may be a liquid sample.

[0201] The liquid may be a biological liquid such as, for instance, blood, urine, saliva.

[0202] The liquid may be a food sample such as soup, yoghurt,

[0203] The liquid may be a beverage sample such as juice (e.g. orange juice), drink concentrate, dairy product (milk, drinkable yoghurt), alcoholic product (e.g. beer, wine), and the like. The liquid may be any raw product or any final product (e.g. oil, paint, cleaner, disinfectant, pharmaceutical, and the like).

[0204] The skilled person understands that the liquid and longitudinal wall (152, 154, 156) surface are selected such that the liquid wets the longitudinal wall surface; an effect of the wetting is capillary action. In particular, a liquid and longitudinal wall surface are selected such that a contact angle and between liquid and longitudinal wall surface is less than 90 deg.

[0205] It is well understood in the art that where the liquid is an aqueous solution the longitudinal wall surface is selected to be hydrophilic. T echniques are well known in the art to adapt or enhance a surface for hydrophilicity. For instance, one technique is to apply a surface treatment, such as plasma treatment, followed by deposition of bovine serum albumin or antisera.

[0206] Conversely, where a liquid is an oil it is well understood in the art that the longitudinal wall surface is selected to be hydrophobic. Techniques are well known in the art to adapt or enhance a surface for hydrophobicity For instance, one technique is silanization.

[0207] The skilled person understands how to pair a liquid and longitudinal wall surface such that capillary action is achieved.

[0208] It is noted that viscosity has no effect on the pairing. It is noted that there is no upper or lower limit on the liquid viscosity within a practical realm of a liquid sample. It is understood that, for instance, a higher viscosity liquid will take longer to rise and for the formation of the TP will be slower, compared with a lower viscosity liquid. A temperature for achieving capillary action is typically in an ambient range (e.g. 10 deg to 45 deg) for most liquids, including aqueous liquids and oils. The skilled person will readily understand how to optimize temperature conditions that are balanced between reducing evaporation of the liquid and increasing viscosity that slows down capillary action.

[0209] The principles of design for systems that employ capillary action are described, for example, in “Capillarity and wetting phenomena: drops, bubbles, pearls, waves”, De Gennes, P. G., Brochard-Wyart, F., & Quere, D. (2003).. Springer Science & Business Media. The sheet (100) is:

[0210] - configured to acquire a tubular structure (124, 124’, 124”) gradually over time and gradually in the flow direction (114) after exposure of the liquid inlets (144, 144’) to the liquid;

[0211] - wherein the plurality of channels (140, 140’) is configured such that:

[0212] - the transport by the capillary action of the liquid in each and every channel (140, 140’) in the flow direction (114) generates an increase of the capillary forces;

[0213] - the moving front of liquid and the resulting increase of capillarity forces creates the tubular portion, TP, (122, 122’, 122”) of the sheet (100) containing tubular structure (124, 124’, 124”).

[0214] The sheet (100) is:

[0215] - configured to acquire a tubular structure (124, 124’, 124”) gradually over time and gradually in the flow direction (114) after exposure of the liquid inlets (144, 144’) to the liquid,

[0216] - wherein the acquiring of the tubular structure (124, 124’, 124”):

[0217] - driven by an increase of capillary forces generated by the liquid in the plurality of channels, wherein the moving front:

[0218] - starts at the immersion end (110) / channel inlet end (142, 142’),

[0219] - advances gradually over time in the flow direction (114);

[0220] - synchronised with the transport by the capillary action of the liquid in each and every channel (140, 140’) in the flow direction (114).

[0221] After exposure of the liquid inlets (144, 144’) to the liquid, the sheet in the activated state starts to curl around its longitudinal direction such that that the channel longitudinal open edges (158, 158’) form an inner (concave) surface of the curl (e.g. FIG 2, Panel A). At a critical imbibition distance of liquid transported by capillary action in the plurality of channels (140, 140’), the tubular portion, TP (122, 122’, 122”) forms starting from the liquid inlets (144, 144’) (e.g. FIG 2, Panel B). As liquid transported by the capillary action advances in the flow direction (114), a length of the TP (122, 122’, 122”) increases gradually also in the flow direction (114) (e.g. FIG 2, Panel C). As liquid transported by the capillary action reaches an end point (equilibrium) the length of the TP (122, 122’, 122”) stops increasing and the sheet reaches a final sheet state (e.g. FIG 2, Panel D).

[0222] The sheet may be disposed in any orientation conducive to capillary action such as vertical, horizontal, inclined to horizontal, and the like, prior to and during the exposing of the liquid inlets (144, 144’) to the liquid. Preferably the sheet (100) is disposed in a vertical orientation prior to and during the exposing of the liquid inlets (144, 144’) to the liquid. The vertical orientation means with respect to the earth vertical as determined, for instance by a plumb line.

[0223] One or more of the plurality of channel (140, 140’) of the sheet (100) as described herein wherein may contain a modified channel longitudinal wall (152, 154, 156) for testing the liquid. When the plurality of liquid inlets (144, 144’) (only) or immersion end (110) (only) are exposed to the liquid, capillary action induces uptake of the liquid into the plurality of channels (140, 140’) and formation of the tubular extending portion, TEP, (122, 122’, 122”) such that the modified longitudinal wall(s) comes into contact with the liquid.

[0224] The modified (channel longitudinal) wall is modified with one or more reactants. The one or more reactants of the modified (channel longitudinal) wall(s) may effect a change in the liquid. For instance, the one or more reactants may detach from the modified (channel longitudinal) wall and solubilise into the liquid, and react with one or more components in the liquid.

[0225] Alternatively or in addition, the liquid may effect a change of the one or more reactants of the modified (channel longitudinal) wall(s). For instance, the one or more reactants may remain attached to the modified wall and be modified by reacting with one or more components in the liquid.

[0226] The testing of the liquid is a result of a reaction between the liquid and one or more reactants. The reaction outcome may be measured using any method, e.g. spectroscopy, visual colour change, immunoassay, fluorescence, and the like. Optical changes (visible, UV, IR, fluorescence) may be read by an optical reader. The samples may be unloaded from the plurality of channels e.g. contacting of the liquid inlets (144,144’) with an absorbent substrate (e.g. paper), and read.

[0227] Each and every channel longitudinal wall (152, 154, 156) may be modified along at least a part of a longitudinal length of the wall. Preferably, each and every channel longitudinal wall (152, 154, 156) is not modified in an immersion zone (143, 143’, FIG. 9). The immersion zone (143, 143’) is disposed at the immersion end (110) of the sheet (100). The immersion zone(143, 143’) is a portion of the channel (140, 140’) starting at the immersion end (110) in particular at the third edge (106) of the sheet (100), in particular at the start line (138). It extends towards the dry end (112) in particular towards the fourth edge (108) of the sheet, in particular towards the finish line (138). A length (izl) of the immersion zone ((143, 143’)) (in a direction from the start towards the dry end (112) or fourth edge (108)) is preferably less than 1 to 20 % of a total length (tl) of a channel (140, 140’) (FIG. 9). The presence of the immersion zone avoids that one or more reactants detach from a modified wall and enter the liquid, thereby contaminating the liquid and all the channels.

[0228] Further provided is a method of sampling simultaneously multiple separate volumes of a liquid comprising:

[0229] - providing the sheet (100) as described herein;

[0230] - exposing (only) the plurality of liquid inlets (144, 144’) or immersion end (110) to the liquid thereby inducing uptake of the liquid by capillary action into the plurality of channels (140, 140’) and formation of the tubular portion, TP, (122, 122’, 122”); wherein as a result of the exposing, multiple separate volumes of the liquid are disposed within the plurality of adjacent channels (140, 140’).

[0231] Further provided is a method of testing a liquid comprising:

[0232] - providing the sheet (100) as described herein, wherein one or more of the plurality of channel (140, 140’) contains a modified (longitudinal) wall (152, 154, 156) for testing the liquid;

[0233] - exposing (only) the plurality of liquid inlets (144, 144’) or immersion end (110) to the liquid thereby inducing uptake of the liquid by capillary action into the plurality of channels (140, 140’) and formation of the tubular portion, TP, (122, 122’, 122”) such that the modified (longitudinal) wall(s) comes into contact with the liquid; thereby testing the liquid.

[0234] The modified (longitudinal) wall is modified with one or more reactants. The one or more reactants of the modified (longitudinal) wall(s) may effect a change in the liquid. For instance, the one or more reactants may detach from the modified (longitudinal) wall and solubilise into the liquid, and react with one or more components in the liquid.

[0235] Alternatively or in addition, the liquid may effect a change of the one or more reactants of the modified (longitudinal) wall(s). For instance, the one or more reactants may remain attached to the modified wall and be modified by reacting with one or more components in the liquid.

[0236] The testing of the liquid is a result of a reaction between the liquid and one or more reactants. The reaction outcome may be measured using any method, e.g. spectroscopy, visual colour change, immunoassay, fluorescence, and the like. Optical changes (visible, UV, I R, fluorescence) may be read by an optical reader. The samples may be unloaded from the plurality of channels e.g. contacting of the liquid inlets (144,144’) with an absorbent substrate (e.g. paper), and read.

[0237] According to one aspect, the exposing of the liquid to one or more reactants of the modified wall(s) effects a change in the liquid in the one or more of the plurality of channel (140, 140’); and

[0238] - method further comprises:

[0239] - contacting the plurality of liquid inlets (144, 144’) of the TP (122, 122’, 122”) with an absorbent substrate, thereby offloading the liquid contained in each channel of the plurality of channels (140, 140’) (via the plurality of liquid inlets (144, 144’)) onto an absorbent substrate;

[0240] - applying one or more assays to the absorbent substrate.

[0241] According to one aspect, the exposing of the liquid to one or more reactants of the modified wall(s) effects a change in the modified wall(s); and

[0242] - method further comprises:

[0243] - uncurling the tubular portion, TP, (122, 122’, 122”) such that the sheet (100) is flat; and - reading the flat sheet using an optical reader;

[0244] Further provided is a method for measuring viscosity of a liquid comprising:

[0245] - providing a sheet (100) as described herein;

[0246] - exposing (only) the plurality of liquid inlets (144, 144’) or immersion end (110) to the liquid thereby inducing uptake of the liquid by capillary action into the plurality of channels (140, 140’) and formation of the tubular portion, TP, (122, 122’, 122”);

[0247] - determining, from a time (vt) taken to reach a reference state which is a state of the sheet (100) in the sheet activated state, the viscosity of the liquid

[0248] The reference state may be any determinable state of the sheet (100) in sheet activated state, such as, for instance, a first appearance of a TP ( / .e. the partial closure of the structure), or a sheet final state. The presence or absence of the reference state may be determined from the sheet (100) in the sheet activated state, for instance, by machine reading {e.g. optical sensor) and / or visual inspection.

[0249] The shorter time (vt) is associated with a lower viscosity. The longer time (vt) is associated with a higher viscosity. A calibration curve for a particular sheet (100) may be prepared based on using methods known to the person skilled in the art.

[0250] The present device provides a fast and inexpensive means to test viscosity of small liquid quantities. The method is non-destructive and the sample can be readily recovered. No additional equipment is needed such as a microscope. The device does not rely on visualisation of the liquid in the channel. The liquid may have a same refractive index as the sheet i.e. not distinguishable from the channel, or the channel may be too small to see the liquid. The time (vt) is read from readily-discernible changes in structure - i.e. from a sheet to a tubular form. In other words, the device is an amplifier of an indicator of speed of transport by the liquid by capillary action.

[0251] A sheet as described herein in the sheet native state.

[0252] A sheet as described herein in the sheet activated state and sheet final state.

[0253] A sheet as described herein in the sheet activated state and sheet final state, prepared by exposing (only) the liquid inlets (144, 144’) to the liquid. A kit comprising a plurality of sheets in the sheet native state as described herein, wherein two or more of the sheets in the sheet native state have different dimensions.

[0254] While the invention has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications, and variations will be apparent to those skilled in the art in light of the foregoing description. Accordingly, it is intended to embrace all such alternatives, modifications, and variations as follows in the spirit and scope of the appended claims.

[0255] Examples

[0256] The herein disclosed aspects and embodiments of the invention are further supported by the following non-limiting example.

[0257] A sheet as described here was prepared according to the following configuration:

[0258] - The sheet in the native state could be made planar;

[0259] - The sheet in the native planar state had dimensions 26.1 x 9.6 mm;

[0260] - The sheet was provided with 8 channels aligned mutually parallel;

[0261] - The sheet had an average channel width (a) of 700 m ± 40 pm;

[0262] - The sheet had an average channel height (b) of 800 pm ± 50 pm;

[0263] - The sheet had an average sheet thickness (c) of 135 pm ± 10 pm;

[0264] - The sheet had a longitudinal barrier body width (d) of 400 pm ± 40 pm;

[0265] - The sheet had an average channel length (L) of 26.1 mm ± 0.2 mm;

[0266] - The material of the sheet was silicone rubber.

[0267] The immersion end of the sheet was exposed to silicone oil having viscosity p = 9.5 x10-3Pa s, surface tension y = 0.021 N / m. Snapshots were taken at t = 0 s (sheet native state, prior to exposure to the liquid), after exposure to the liquid (sheet activated state), and until no further extension of the tubular portion (sheet final state). The results are shown in FIG. 5. Observed was a gradual formation of the tubular portion within a period of 20 seconds. Initially, the liquid is transported into the plurality of channels by capillary action and the sheet gradually curls without any formation of a tubular portion (t = 0.1 s to 0.7 s). Subsequently a distance of liquid transported by capillary action into the channels reaches a critical imbibition distance and a tubular portion forms (t = 0.8 s). Subsequently, as liquid transported by capillary action into the channels continues, the tubular portion extends (t = 1 s to 3 s). Where the distance of liquid transported by capillary action reaches an equilibrium, tubular portion stops extending (sheet final state) (t = 20 s). Each channel has become a closed channel in the tubular portion. A central tubular lumen has formed in the tubular portion.

Claims

37Claims1. A sheet (100) having a sheet first side (116) and an opposing sheet second side (118) wherein- only the sheet first side (116) is disposed with a plurality of adjacent and parallel capillary channels, channels (140, 140’);- each and every channel (140, 140’) comprises a channel inlet end (142, 142’) at one longitudinal end of the channel (140, 140’) and a liquid inlet (144, 144’) at the channel inlet end (142, 142’) configured for inlet of the liquid;- each and every channel liquid inlet (144, 144’) is aligned on the sheet first side along a start line (138), wherein the start line (138) is disposed at an immersion end (110) of the sheet;- the sheet (100) has a first edge (102) and an opposing second edge (104), both edges (102, 104) parallel with the plurality of channels (140, 140’);- the sheet (100) comprises a native state prior to exposing the liquid inlets (144, 144’) to the liquid, and an activated state induced by exposure of the liquid inlets (144, 144’) to the liquid;- in the native state of the sheet (100) each and every channel (140, 140’) is an open channel having a channel longitudinal open edge (158, 158’) along an entire longitudinal length of the channel (140, 140’);- wherein the sheet (100) is configured such that in the active state, the exposure of the immersion end (110) of the sheet to the liquid induces the formation in the sheet (100) of a tubular portion, TP, (122, 122’, 122”) that is a portion of a length of the sheet (100) parallel to the plurality of channels (140, 140’), wherein the TP (122, 122’, 122”) has:- a tubular structure (124, 124’, 124”) wherein:- each and every of channel (140, 140’) of the plurality of channels is present and disposed on an internal surface (116a) of the tubular structure (124, 124’, 124”);- each and every channel (140, 140’) of the plurality of channels (140, 140’) is closed thereby forming a separate longitudinal channel lumen (164, 164’) for each and every channel (140, 140’) in the TP (120, 120’, 120”); and- the tubular structure is curved around a folding axis (109) disposed parallel to the plurality of channels (140, 140’) within the TP (122, 122’, 122”);- a length (120, 120’, 120”) that increases gradually in a flow direction (114) of the liquid along the plurality of channels (140, 140’); and38- wherein, in the gradually increasing length (120, 120’, 120”) of tubular structure (124, 124’, 124”), a portion of the opposing first edge (102) and a portion of the second opposing edge (104) of the sheet (100) co-operate together to form a length of closed edge (132) thereby forming the tubular structure (124, 124’, 124”) in the TP (122, 122’, 122”).

2. The sheet according to claim 1, wherein each and every channel (140, 140’, 140’”) of the plurality of channels is formed from a pair of adjacent longitudinal barrier bodies (150, 150’, 150’”) that flank and separate the channel.

3. The sheet according to claim 1 or 2, wherein: where each and every channel (140, 140’, 140’”) of the plurality of channels is closed in the TP (122, 122’, 122”), the adjacent longitudinal barrier bodies (150, 150’, 150’”) that flank and separate each and every channel (140, 140’, 140’”) are in mutual contact, thereby closing the channel along a longitudinal closed edge, CLCE (162, 162’, 162’”) within the TP (122, 122’, 122”).

4. The sheet according to any one of claims 1 to 3, where a quantity of channels is N, and a dimension of the channels satisfy the condition:wherein: a is an average channel width (a) and b is an average channel height (b) for the sheet, where- (a) is a channel width as determined from a transverse cross-sectional view of the sheet when the sheet is planar;- (b) is a channel height as determined from a transverse cross-sectional view of the when the sheet is planar.

5. The sheet (100) according to any one of claims 1 to 4, configured such that in the activated state:- the tubular structure (124, 124’, 124”) of the TP (120, 120’, 120”) contains a central tubular lumen (128) defined by a plurality of longitudinal barrier bodies (150, 150’),wherein the plurality of adjacent channels are mutually separated by the plurality of longitudinal barrier bodies (150, 150’) in the sheet (100).

6. The sheet (100) according to any one of claims 1 to 5, wherein the plurality of channels (140, 140’) is configured such that:- a transport by the capillary action of the liquid in the plurality of channels (140, 140’) in the flow direction (114) generates an increase of the capillary force; and- the increase of the capillary force creates the tubular portion, TP, (122, 122’, 122”) of the sheet (100) containing tubular structure (124, 124’, 124”).

7. The sheet (100) according to any one of claims 1 to 6, wherein each and every channel of the plurality of channels (140, 140’) has a channel longitudinal wall (152, 154, 156) along a longitudinal length of the channel (140, 140’), and at least one of the channel longitudinal wall (152, 154, 156) is modified for testing of the liquid.

8. The sheet (100) according to claim 7, wherein the at least one of the modified channel longitudinal wall (152, 154, 156) is not modified in an immersion zone (143, 143’) that is a longitudinal portion of the channel disposed at the immersion end (110) of the sheet (100).

9. A method of sampling simultaneously multiple separate volumes of a liquid comprising:- providing a sheet (100) according to any one of claims 1 to 8;- exposing the plurality of liquid inlets (144, 144’) to the liquid thereby inducing uptake of the liquid by capillary action into the plurality of channels (140, 140’) and formation of the tubular portion, TP, (122, 122’, 122”); wherein as a result of the exposing, multiple separate volumes of the liquid are sampled within the plurality of adjacent channels (140, 140’).

10. A method for measuring viscosity of a liquid comprising:- providing a sheet (100) according to any one of claims 1 to 8;- exposing the plurality of liquid inlets (144, 144’) to the liquid thereby inducing uptake of the liquid by capillary action into the plurality of channels (140, 140’) and formation of the tubular portion, TP, (122, 122’, 122”);- determining, from a time (vt) taken to reach a reference state which is a determinable state of the sheet (100) in the sheet activated state, the viscosity of the liquid.

11. The method according to claim 10, wherein a larger time (vt) is indicative of a higher liquid viscosity compared with a shorter time (vt).

12. A method for testing a liquid comprising:- providing a sheet (100) according to any one of claims 1 to 8, wherein one or more of the plurality of channels (140, 140’) contains a modified wall (152, 154, 156) for testing the liquid;- exposing the plurality of liquid inlets (144, 144’) to the liquid thereby inducing uptake of the liquid by capillary action into the plurality of channels (140, 140’) and formation of the tubular portion, TP, (122, 122’, 122”) such that the modified wall(s) comes into contact with the liquid; wherein as a result of the exposing and the modified wall(s) coming into contact with the liquid, the liquid is tested.

13. The method according to claim 12 wherein the exposing of the liquid to one or more reactants of the modified wall(s) effects a change in the liquid in the one or more of the plurality of channel (140, 140’); and- method further comprises:- contacting the plurality of liquid inlets (144, 144’) of the TP (122, 122’, 122”) with an absorbent substrate, thereby offloading the liquid contained in each channel of the plurality of channels (140, 140’) onto the absorbent substrate;- applying one or more assays to the absorbent substrate.

14. The method according to claim 12 wherein the exposing of the liquid to one or more reactants of the modified wall(s) effects a change in the modified wall(s); and- method further comprises:- uncurling the tubular portion, TP, (122, 122’, 122”) such that the sheet (100) is flat; and- reading the flat sheet using an optical reader.

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