A device for the detection and/or quantification of an analyte in a sample, wherein (a) said device comprises: an aqueous two-phase system (ATPS) comprising a mixed phase solution that separates into a first phase solution and a second phase solution where, in use, said first phase solution becomes a leading phase and said second phase solution becomes a lagging phase; a lateral-flow assay or a flow-through assay; and a probe that associates with said first phase solution in said leading phase of said ATPS; and a development reagent that associates with said second phase solution in said lagging phase of said ATPS; or (b) said device comprises: a flow-through system comprising: a concentration component comprising an aqueous two-phase system (ATPS) comprising a mixed phase solution where, in use, said first phase solution becomes a leading phase and said second phase solution becomes a lagging phase; a probe that associates with said first phase solution in said leading phase of said ATPS; and a development reagent that associates with said second phase solution in said lagging phase of said ATPS; and a detection component disposed beneath said concentration component; wherein, for device (a) and device (b), said probe comprises an enzyme decorated on the surface of said probe and said development reagent comprises a substrate that reacts with said enzyme to form a visible product, or said probe is decorated with an enzyme substrate and said development reagent comprises an enzyme that reacts with said enzyme substrate to form a visible product, or said development reagent comprises a reagent that reacts with a said probe to form a visible signal. (a) said device comprises: an aqueous two-phase system (ATPS) comprising a mixed phase solution that separates into a first phase solution and a second phase solution where, in use, said first phase solution becomes a leading phase and said second phase solution becomes a lagging phase; a lateral-flow assay or a flow-through assay; and a probe that associates with said first phase solution in said leading phase of said ATPS; and a development reagent that associates with said second phase solution in said lagging phase of said ATPS; or an aqueous two-phase system (ATPS) comprising a mixed phase solution that separates into a first phase solution and a second phase solution where, in use, said first phase solution becomes a leading phase and said second phase solution becomes a lagging phase; a lateral-flow assay or a flow-through assay; and a probe that associates with said first phase solution in said leading phase of said ATPS; and a development reagent that associates with said second phase solution in said lagging phase of said ATPS; or (b) said device comprises: a flow-through system comprising: a concentration component comprising an aqueous two-phase system (ATPS) comprising a mixed phase solution where, in use, said first phase solution becomes a leading phase and said second phase solution becomes a lagging phase; a probe that associates with said first phase solution in said leading phase of said ATPS; and a development reagent that associates with said second phase solution in said lagging phase of said ATPS; and a detection component disposed beneath said concentration component; wherein, for device (a) and device (b), said probe comprises an enzyme decorated on the surface of said probe and said development reagent comprises a substrate that reacts with said enzyme to form a visible product, or said probe is decorated with an enzyme substrate and said development reagent comprises an enzyme that reacts with said enzyme substrate to form a visible product, or said development reagent comprises a reagent that reacts with a said probe to form a visible signal. a flow-through system comprising: a concentration component comprising an aqueous two-phase system (ATPS) comprising a mixed phase solution where, in use, said first phase solution becomes a leading phase and said second phase solution becomes a lagging phase; a probe that associates with said first phase solution in said leading phase of said ATPS; and a development reagent that associates with said second phase solution in said lagging phase of said ATPS; and a detection component disposed beneath said concentration component; a concentration component comprising an aqueous two-phase system (ATPS) comprising a mixed phase solution where, in use, said first phase solution becomes a leading phase and said second phase solution becomes a lagging phase; a probe that associates with said first phase solution in said leading phase of said ATPS; and a development reagent that associates with said second phase solution in said lagging phase of said ATPS; and a detection component disposed beneath said concentration component; wherein, for device (a) and device (b), said probe comprises an enzyme decorated on the surface of said probe and said development reagent comprises a substrate that reacts with said enzyme to form a visible product, or said probe is decorated with an enzyme substrate and said development reagent comprises an enzyme that reacts with said enzyme substrate to form a visible product, or said development reagent comprises a reagent that reacts with a said probe to form a visible signal.