Method and device for electrochemical immunoassay of multiple analytes

A device for detecting or quantifying one or more analytes in a liquid sample, said device comprising

• a sample chamber for holding the liquid sample,
• at least two redox reversible species located for contact with the liquid sample in the chamber, each redox reversible species capable of diffusion in said liquid sample at least in the presence of a respective predetermined analyte, said redox reversible species having respective redox potentials differing by at least 50 millivolts, and at least one of said redox reversible species comprising a ligand capable of binding to a specific binding partner for the analyte,
• an electrode structure for contact with the liquid sample, said electrode structure including a reference electrode and working electrodes dimensioned to allow diffusional recycling of a diffusible redox reversible species in the liquid sample in contact with the electrode structure when a predetermined redox-reversible-species-dependent cathodic potential is applied to one working electrode and a predetermined redox-reversible-species-dependent anodic potential is applied to a second working electrode, said diffusional recycling of said species being sufficient to sustain a measurable current through each working electrode, and
• conductors communicating with the respective electrodes for applying said anodic potential and said cathodic potential and for carrying the current conducted by the electrode.

A kit for measuring the concentration of one or more analytes in a liquid sample, said kit comprising

• at least two redox reversible species for contact with the liquid sample, each capable of diffusion in the liquid sample at least in the presence of a predetermined analyte, at least one species comprising a conjugate of a ligand analog of an analyte and a redox reversible label, said redox reversible species having respective redox potentials differing by at least 50 millivolts;
• a specific binding partner for each analyte;
• an electrode structure for contact with the liquid sample, said electrode structure including a reference electrode and working electrodes dimensioned to allow diffusional recycling of diffusible redox reversible species in the sample when a predetermined redox-reversible-species-dependent-cathodic potential is applied to one working electrode and a predetermined redox-reversible-species-dependent-anodic potential is applied to the second working electrode, said diffusional recycling of said species means sufficient to sustain a measurable current through the sample;
• and
• conductors communicating with the respective electrodes for applying said anodic potential and said cathodic potential and for carrying the current conducted by the electrodes.