An ion-sensitive sensor includes a dielectric layer comprising Al2O3 having a functionalized surface configured to bond with an analyte. The ion-sensitive sensor is immersed in an electrolytic solution containing a concentration of alkali ions. An electrode is arranged to apply an electric potential to the functionalized surface of the ion-sensitive sensor. In some embodiments the ion-sensitive sensor is an ion-sensitive silicon FET. In some embodiments the ion-sensitive sensor is an ion-sensitive polymer FET. In some embodiments, the electrode comprises a perforated gate metal layer disposed on the gate dielectric layer of an ion-sensitive FET, and the functionalized surface is disposed in openings of the perforated gate metal layer. In some embodiments the dielectric layer comprises a multi-layer dielectric stack including at least one Al2O3 layer. In some embodiments the dielectric layer is deposited by atomic layer deposition (ALD).
