A facile membraneless method for detecting alkali-metal cations using organic electrochemical transistors

Abstract

Organic electrochemical transistors (OECTs) have garnered significant attention due to their exceptional capability to efficiently monitor biological signals, making them an ideal platform for bio-signal detection. Many recent research studies have focused on detecting alkali-metal cations, such as the key cellular messengers of sodium (Na⁺) and potassium (K⁺) ions. We now report a straightforward and effective method for fabricating membraneless ion-selective OECTs (IS-OECTs) by directly incorporating crown ethers, specifically 18-crown-6 (18C6) and 15-crown-5 (15C5) ethers, into a polymer matrix of p(g2T-TT), a conjugated polymer bearing glycol side chains. The resulting IS-OECTs demonstrated good sensitivity and a low limit of detection for both Na⁺ and K⁺ ions. Importantly, stability tests revealed that 15C5-mixed polymer OECTs show no degradation over 450 continuous cycles in a NaCl aqueous solution, underscoring the excellent retention performance. This study not only provides a facile and efficient approach for the development of ion detection systems based on OECTs but also opens new avenues for advancing bioelectronic devices in future research endeavors.