Abstract: The invention relates to “solid state” chemiresistor sensors with electric control of the affinity of a chemosensitive material. The configurations of the present invention enable the fast regeneration of the sensor after analyte binding, which therefore increases selectivity. In one embodiment the chemiresistor sensor is implemented as a multi-electrode chemiresistor, comprising 4 electrodes for the separate measurement of the resistance of the chemosensitive material and the contact resistance, and 2 further electrodes to control the redox state of the chemosensitive sensor material, thereby facilitating fast and effective regeneration of the sensor.