An ionic current sensor array includes a master bias generator and a plurality of sensing cells. The master bias generator is configured to generate a bias voltage. Each sensing cell includes an ionic current sensor, an integrating capacitor, a sense transistor coupled between the integrating capacitor and the ionic current sensor, and an amplifier coupled to provide a reference voltage to bias the ionic current sensor. The amplifier includes a first transistor and a second transistor. The first transistor is coupled to receive the bias voltage, and the second transistor is coupled to the first transistor to provide the reference voltage to the ionic current sensor. The second transistor is also coupled between a source of the sense transistor and the gate of the sense transistor.