A method of fabricating a self-wicking monolith for processing a fluid sample, the method comprising: providing a hydrophilic monomer and a linker monomer, the linker monomer having two polymerizable groups spaced apart by a linker comprising at least one -C 2 O- group; wherein each R is individually a hydrogen or an organic group; optionally wherein one or more further monomers are provided; optionally wherein one or more different linker monomers are provided; obtaining a polymerizable composition by combining said hydrophilic monomer and linker monomer in a porogenic solvent; and obtaining at least one additional polymerizable composition containing a hydrophilic monomer and a linker monomer in a porogenic solvent; wherein the polymerizable composition and the at least one additional polymerizable composition vary in at least one of: hydrophilic monomer and/or linker monomer identity; total non-linker monomer to linker monomer ratio; porogenic solvent; the concentration of hydrophilic monomer, linker monomer, and further monomer, if present, in the solution; the presence and identity of one or more further monomers and the presence and identity of an initiator; and then - polymerising the polymerizable composition to form the monolith, the method comprising the step of providing the compositions at different locations within a mold prior to polymerization, such that the monolith comprises a plurality of zones, wherein different zones have different wicking properties and/or chemical properties. providing a hydrophilic monomer and a linker monomer, the linker monomer having two polymerizable groups spaced apart by a linker comprising at least one -C 2 O- group; wherein each R is individually a hydrogen or an organic group; optionally wherein one or more further monomers are provided; optionally wherein one or more different linker monomers are provided; optionally wherein one or more further monomers are provided; optionally wherein one or more different linker monomers are provided; obtaining a polymerizable composition by combining said hydrophilic monomer and linker monomer in a porogenic solvent; and obtaining at least one additional polymerizable composition containing a hydrophilic monomer and a linker monomer in a porogenic solvent; wherein the polymerizable composition and the at least one additional polymerizable composition vary in at least one of: hydrophilic monomer and/or linker monomer identity; total non-linker monomer to linker monomer ratio; porogenic solvent; the concentration of hydrophilic monomer, linker monomer, and further monomer, if present, in the solution; the presence and identity of one or more further monomers and the presence and identity of an initiator; and then - polymerising the polymerizable composition to form the monolith, the method comprising the step of providing the compositions at different locations within a mold prior to polymerization, such that the monolith comprises a plurality of zones, wherein different zones have different wicking properties and/or chemical properties. hydrophilic monomer and/or linker monomer identity; total non-linker monomer to linker monomer ratio; porogenic solvent; the concentration of hydrophilic monomer, linker monomer, and further monomer, if present, in the solution; the presence and identity of one or more further monomers and the presence and identity of an initiator; and then - polymerising the polymerizable composition to form the monolith, the method comprising the step of providing the compositions at different locations within a mold prior to polymerization, such that the monolith comprises a plurality of zones, wherein different zones have different wicking properties and/or chemical properties. - polymerising the polymerizable composition to form the monolith, the method comprising the step of providing the compositions at different locations within a mold prior to polymerization, such that the monolith comprises a plurality of zones, wherein different zones have different wicking properties and/or chemical properties.