A method for sensing analyte. The method includes the steps of sensing one or more parameters in reaction to the presence of one or more analytes and outputting a current therefrom in accordance with level of the sensed parameter by each of a plurality of sensors, each of the plurality of sensors being provided in one or more sensor array columns, selectively heating one or more of the sensor array columns by a heating element, and receiving an output current from one of the plurality of sensors from each of the plurality of sensor arrays by a Voltage Controlled Oscillator (VCO) arranged in a VCO array. The method further includes the steps of generating an output oscillation frequency by each VCO in accordance with the level of the received output current, and counting a number of oscillations over a predetermined time received from each of the plurality of VCOs in the VCO array by a plurality of counters arranged in a counter array.