Provided is a sensor unit (104) for detecting an analyte (128) in an aqueous medium. The sensor unit comprises a surface (124) for receiving the aqueous medium thereon. Capture species (126) immobilized on the surface reversibly bind the analyte. A detector (130) detects the analyte when the analyte is bound to the capture species. The sensor unit further comprises an electrolysis assembly (132). The electrolysis assembly comprises a plurality of spatially separated electrically conductive areas (134) on the surface, and a power supply (136) for supplying a voltage across at least two of the electrically conductive areas. The voltage is sufficient to electrolyse the aqueous medium received on the surface. Further provided is a body fluid monitoring device (101) comprising the sensor unit, and a method for detecting an analyte.
