Dual-gate Organic Field-Effect Transistrors as Potentiometric Sensors an Aqueous Solution

Buried electrodes and protection of the semiconductor with a thing passivation layer are used to yield dual gate organic transducers. The process technology is scaled up to 150 mm wafers. The transducers are potentiometric sensors where the detectors relies on measuring a shift in the threshold voltage caused by changes in the electrochemical potential at the second gate dielectric. Analytes can only be detected within the Debye screeing length. The mechanism is assessed by pH measurements. The threshold voltage shift depends on pH as Delta V(th) = (C(top)/C(bottom)) x 58 mV per pH unit, indicating that the sensitivity can be enhanced with respect to conventional ion-sensitive field-effect transistors (ISFETs) by adjusting the ratio of the top and bottom gate capacitances. Remaining challenges and opportunities are discussed.