Extended gate organic field effect transistor for calcium ion sensing towards biomedical applications

The measurement of calcium ions (Ca2+) concentration is crucial for several biomedical applications because it plays a key role in various physiological processes, including cellular signalling, muscle contraction, bone metabolism, and the release of neurotransmitters. In this paper, we propose an innovative flexible sensor based on an Extended Gate Organic Field Effect Transistor (ExG-OFET) coupled with a liquid-processable ion-selective membrane. This novel approach enables highly sensitive (exceeding 60 mV dec‑1) and selective ion detection, with a limit of detection in the low μM range, outperforming conventional ion-sensitive electrodes (ISEs) due to the intrinsic electronic amplification of the transistor architecture. Moreover, the simple fabrication process and the use of flexible, cost-effective materials, make this device a versatile, low-cost solution for a wide range of biomedical applications, from in vitro electrophysiology to epidermal electronics. This study highlights the potential of the ExG-OFET platform as a promising alternative to traditional ion detection systems.