No abstract

The construction of organic electrochemical transistors (OECTs) using poly(3,4‐ethylenedioxythiophene):tosylate and polyallylamine hydrochloride composites as conducting channel material is presented. The regulation of the polyelectrolyte‐to‐conducting polymer proportion allows one to easily tune both electronic and ionic characteristics of the transistors, yielding devices with low threshold voltages while preserving high transconductance, which is an essential requisite for the effective integration of OECTs with biological systems. Also, the incorporation of the polyelectrolyte enhances the transient response of the OECTs during the ON/OFF switching, probably due to improved ion transport. Furthermore, the integration of pH‐sensitive amino moieties not only improves the pH response of the transistors but also allows for the non‐denaturing electrostatic anchoring of functional enzymes. As a proof‐of‐concept, acetylcholinesterase is electrostatically immobilized by taking advantage of the NH2 moieties, and the OECTs‐based sensors are able to successfully monitor the neurotransmitter acetylcholine in the range 5–125 µm.