Abstract: An assay method comprising the step of binding a second substance to a first substance immobilized to a solid phase surface, the first substance being either a ligand or a species bound directly or indirectly thereto. The method is characterized in that the solid phase surface having the first substance immobilized thereto exhibits and electric charge, and that the reaction for binding the second substance to the first substance is performed at an ionic strength below 100 mM, and at such pH conditions that the electric charge of the second substance is opposite to that of the solid phase surface so that the second substance is electrostatically attracted by the solid phase surface to be concentrated thereto.

Abstract: In a method of determining the refractive index of a gaseous, liquid or solid sample, preferably a gaseous or liquid sample, there is used a waveguide resonator (1) which includes an open waveguide (4) and a closed waveguide (5) located adjacent the open waveguide. The sample is brought to the vicinity of the closed waveguide (5) so as to influence the proximal surroundings of the waveguide and therewith its effective refractive index. Light derived from a light source (9) is coupled to one end of the open waveguide (4) and transmitted light is measured at the other end of the open waveguide to establish the influence of the sample on the resonance wavelength and therewith determine the refractive index of the sample or a sample-related refractive index difference. A device for carrying out the method includes a waveguide resonator having a sample contact area (12) adjacent the closed waveguide (5) of the waveguide resonator.

Abstract: In assays of the type which comprise contacting the sample containing the analyte to be detected with a solid phase surface supporting a ligand capable of binding the analyte, undesired binding to the surface is prevented to a substantial degree by adding to the sample one or more components of the material forming the ligand supporting solid phase surface, which components are in at least partially soluble form and capable of interacting with constituents of the sample medium.

Abstract: A valve of the membrane valve type comprises a valve body with two fluid flow channels (5, 5') separated by a land portion which forms a valve seat (6) having a sealing surface for co-operation with a flexible membrane (7) mounted over a duct (8) which opens in front of the valve seat and is arranged for fluid pressure actuation of the membrane between a closing position, where the membrane (7) sealingly contacts the valve seat (6), and an opening position where there is a flow channel communicating space ( 11) between the valve seat (6) and the membrane (7).

Abstract: A method of characterizing a macromolecule by studying its interactions with ligands comprises the determination of the mutual influence of ligand interactions by, after the macromolecule has interacted with at least one ligand, contacting the macromolecule with at least one additional ligand, either the macromolecule or the additional ligand or ligands having been bound to a sensor surface, determining interaction by detecting a consequential change in the physico-chemical properties of the sensor surface, and on the basis of the determined mutual dependence between the ligand interactions discriminating between epitopes of the macromolecule and mapping their relative positions.

Abstract: Methods for functionalizing sensing surfaces to be used in systems for measuring simultaneously several properties of one biomolecule as well as for simultaneously measuring the concentrations of a plurality of biomolecules in a sample. The invention furthermore also relates to sensor units containing such surfaces, to the use thereof for surface characterization of biomolecules, and to a reagent kit for functionalization of sensing surfaces.

Abstract: A leakage-proof sealing means is provided in a microfluidic channel assembly of the type having first and second flat surface members which when pressed against each other define a microfluidic channel system between them, by recessing a sealing groove structure into the flat surface of the first member, and applying against the first member a counter mould surface having an aligned groove and/or ridge structure of smaller width than the sealing groove structure to define a mould cavity therewith, into which a fluid sealing material is introduced and hardened to form a resilient seal, the top part of which projects above the edges of the sealing groove structure while leaving sufficient space in the upper part thereof to permit complete accommodation of the top part of the resilient seal when compressed by the second assembly member.

Abstract: A matrix coating suitable for use in a biosensor is provided. This matrix coating comprises a hydrogel bound to a surface and via which a desired ligand can be bound. This hydrogel is activated to contain charged groups for bringing about the concentration of biomolecules carrying an opposite charge to that of said charged groups, and reactive groups for covalently binding the biomolecules concentrated to the matrix coating.

Abstract: The microfluidic structure comprises first and second substantially planar form-stable base layers and an intermediate spacing layer of elastic material, said spacing layer being recessed to define a microcavity or channel system with at least one of said first and second base layers. The structure is produced by moulding the spacing layer, optionally applied to or integral with a first base layer, against a planar mould, and the microcavity or channel system is completed by applying a second base layer, and optionally said first base layer, to the spacing layer.

Abstract: An optical biosensor system using internal reflection versus angle of incidence determination for the detection of biomolecules, the system comprising a sensor unit (10) with at least two sensing surfaces (39A-D), a source of light (1), and lens means (2) for forming a convergent beam of light which is focused in wedge-shape fashion to form a streak of light (5) extending transversely over all the sensing surfaces; a photodetector device (7) in the form of a two-dimensional matrix of individual photodetector; optical imaging instrumentation in the form of an anamorphic lens system (6) for the purpose of imaging rays of reflected light from the sensing surfaces on each its own column of photodetectors, so that for each sensing surface there is a corresponding set of columns of photodetectors; and an evaluation unit (8) for determining the minimum reflectance or the resonance angle at each of the sensing surfaces.

Abstract: A sensing surface suitable for use in a biosensor, comprising:a film of a free electron metal selected from the group consisting of copper, silver, aluminum and gold; anda densely packed monolayer of an organic molecule X-R-Y coated on one of the faces of said film where X is a group selected from the group consisting ofasymmetrical or symmetrical disulfide (--SSR'Y', -SSRY, sulfide (-SR'Y', -SRY), diselenide (-SeSeR'Y', -SeSeRY), selenide (SeR'Y', -SeRY),thiol (-SH), isonitrile, nitro (-NO.sub.2), selenol (-SeH), trivalent phosphorus compounds, isothiocyanate, xanthate, thiocarbamate, phosphine,thio acid and dithio acid (-COSH, -CSSH)where R and R' are hydrocarbon chains optionally interrupted by hetero atoms, of a length exceeding 10 atoms, wherein in the case of an asymmetrical molecule, R' or R may be H, and Y and Y' are active groups for covalently binding ligands or a biocompatible porous matrix.

Abstract: An optical interface means for non-permanent passive coupling of light between two optically transparent media comprises a support member (3), and at least one shaped body (6) of an optically transparent elastic material supported thereby and adapted to resiliently contact said solid medium or media, said elastic material having a matching refractive index in respect of said media.