An apparatus includes an oxide layer having ion transport channels that facilitate the migration of oxygen ions from a first side to a second side of the layer. Specifically, molecular oxygen is decomposed into oxygen ions at the first side, and oxygen ions recombine into molecular oxygen at the second side. The apparatus includes a first chamber having a polarizable medium located on the second side of the oxide layer; a second chamber having an analyte that includes dissolved oxygen is located on the first side. The apparatus further includes a gate electrode that is in contact with, and applies a voltage to, the polarizable medium; in this manner, an electric field is applied to the second side of the oxide layer, which drives oxygen ions across the oxide layer. The apparatus can be used as an oxygen sensor, e.g., for detecting oxygen in a liquid such as blood.