There are provided nonselective, nonenzymatic electrochemical sensor systems for detection and/or measurement of a redox-active analyte in a liquid sample. Sensor systems comprise a nonenyzmatic electrode system having a working electrode, a counter electrode, and a reference electrode, where the working electrode comprises a nonenzymatic modifier selected to increase sensitivity and/or selectivity of the working electrode for an analyte. Sensor systems are wearable, washable and reusable, and can be used for detection of multiple analytes in a sample.