A sensor unit for detecting an analyte in an aqueous medium, the sensor unit comprising: a surface for receiving the aqueous medium thereon; capture species for reversibly binding said analyte, the capture species being immobilized on said surface; a detector for detecting, determining or assessing analyte bound to said capture species; and an electrolysis assembly comprising: at least three spatially separated electrically conductive areas on said surface; and a power supply configured to implement: a first setting in which a voltage sufficient to electrolyse the aqueous medium received on said surface is supplied across a first pairwise combination of said at least three conductive areas; and characterized in that the power supply is further configured to implement a second setting in which a voltage sufficient to electrolyse the aqueous medium received on said surface is supplied across a second pairwise combination of said at least three conductive areas, the second pairwise combination being different from said first pairwise combination. a surface for receiving the aqueous medium thereon; capture species for reversibly binding said analyte, the capture species being immobilized on said surface; a detector for detecting, determining or assessing analyte bound to said capture species; and an electrolysis assembly comprising: at least three spatially separated electrically conductive areas on said surface; and a power supply configured to implement: a first setting in which a voltage sufficient to electrolyse the aqueous medium received on said surface is supplied across a first pairwise combination of said at least three conductive areas; and characterized in that the power supply is further configured to implement a second setting in which a voltage sufficient to electrolyse the aqueous medium received on said surface is supplied across a second pairwise combination of said at least three conductive areas, the second pairwise combination being different from said first pairwise combination. at least three spatially separated electrically conductive areas on said surface; and a power supply configured to implement: a first setting in which a voltage sufficient to electrolyse the aqueous medium received on said surface is supplied across a first pairwise combination of said at least three conductive areas; and characterized in that the power supply is further configured to implement a second setting in which a voltage sufficient to electrolyse the aqueous medium received on said surface is supplied across a second pairwise combination of said at least three conductive areas, the second pairwise combination being different from said first pairwise combination. a first setting in which a voltage sufficient to electrolyse the aqueous medium received on said surface is supplied across a first pairwise combination of said at least three conductive areas; and characterized in that the power supply is further configured to implement a second setting in which a voltage sufficient to electrolyse the aqueous medium received on said surface is supplied across a second pairwise combination of said at least three conductive areas, the second pairwise combination being different from said first pairwise combination. <EOS>