Ion sensitive detector

An ISFET detector for determining concentration of target ions in a fluid, the ISFET detector comprising:

• a transistor comprising:
• a semiconductor substrate comprising a source and a drain having source and drain electrodes respectively and a channel region between them in the semiconductor substrate;
• an insulating material overlying the channel region;
• and
• a gate electrode formed on the insulating material;
• a reference electrode electrifiable to establish an electric field in the channel region;
• a conducting layer comprising an electrically conducting material;
• an accumulator layer formed on the conducting layer, the accumulator layer comprising a layer of material of thickness less than or equal to about 2 nm (nanometers) that accumulates target ions responsive to a concentration of the target ions in the fluid;
• and
• a conducting element comprising a switch selectively operable to electrically connect the conducting layer to, or disconnect the conducting layer from, the gate electrode.