An input device includes a plurality of sensor electrodes and a processing system that is operable in at least a first mode or a second mode. The processing system is configured to receive an input current from a pair of the sensor electrodes. When operating the first mode, the processing system is configured to measure a capacitance across the pair of sensor electrodes based on the received input current. When operating the second mode, the processing system is configured to measure a resistance between the pair of sensor electrodes based on the received input current.