Polymeric ion-selective membrane functionalized gate-electrodes: Ion-selective response of electrolyte-gated poly (3-hexylthiophene) field-effect transistors

We demonstrate the ion-selective response of an electrolyte-gated organic field-effect transistor (IS-OFET) towards the two prominent second messengers for cell-cell communication: K⁺ and Ca²⁺. The ion-selective response is achieved by modifying the gate-electrode with different polymeric ion-selective membranes. The sensing mechanism relies on the transduction of the ionic signal in an electrical one due to a concentration-dependent change in the membrane potential at the gate/electrolyte interface which leads to a change in the effective gate potential and thus alters charge transport in the semiconducting channel. These sensors can be successfully used to selectively detect concentrations of primary ions down to a concentration in the μM range even in solutions with an ionic background of 150 mM. Our approach represents a valuable strategy for the realization of portable, multi-purpose and low-cost biosensing devices.