Microfabricated Ion‐Selective Transistors with Fast and Super‐Nernstian Response

Abstract

Transistor‐based ion sensors have evolved significantly, but the best‐performing ones rely on a liquid electrolyte as an internal ion reservoir between the ion‐selective membrane and the channel. This liquid reservoir makes sensor miniaturization difficult and leads to devices that are bulky and have limited mechanical flexibility, which is holding back the development of high‐performance wearable/implantable ion sensors. This work demonstrates microfabricated ion‐selective organic electrochemical transistors (OECTs) with a transconductance of 4 mS, in which a thin polyelectrolyte film with mobile sodium ions replaces the liquid reservoir. These devices are capable of selective detection of various ions with a fast response time (≈1 s), a super‐Nernstian sensitivity (85 mV dec−1), and a high current sensitivity (224 µA dec−1), comparing favorably to other ion sensors based on traditional and emerging materials. Furthermore, the ion‐selective OECTs are stable with highly reproducible sensitivity even after 5 months. These characteristics pave the way for new applications in implantable and wearable electronics.

Selective Ion Detection with Integrated Organic Electrochemical Transistors

“…Focusing on the electrical transfer characteristics, the I ds -V gs curves shifts to less positive voltages when the ion concentration increases. [28,35] More in detail, an increase in the primary ion concentration results in an increase of the potential between the analyte and the ion selective membrane. Consequently, for a given V gs an increased number of Na + from the PSSNa layer will be injected into the PEDOT:PSS film and the channel current will be reduced.…”

Organic Bioelectronic Devices for Selective Biomarker Sensing : Towards Integration with Living Systems

“…For the far more common p-type depletion mode OECT, increasing concentrations of ions induce higher ionic charge at the interface with the channel, de-doping more effectively the semiconducting polymer. Ions sensing with OECT based devices has been proved for various cations 97 and in combination with ion-selective membrane 98,99 .…”

Regulating Light‐Sensitive Gate of Organic Photoelectrochemical Transistor toward Sensitive Biodetection at Zero Gate Bias

“…Organic electrochemical transistor (OECT) has emerged as one of the state-of-the-art techniques for biosensing due to its unique set of advantages such as easy fabrication, cost effectiveness, good stability, biocompatibility, operation in aqueous environments, and especially, inherent signal amplification. [1][2][3][4] They have been used as powerful biosensors toward ions, [5,6] molecules, [7] proteins, [8] cells, [9][10][11] and DNA. [12] Typically, an OECT consists of a source electrode (S) and a drain electrode (D) bridged by an organic semiconductor channel (C), a gate electrode (G), an electrolyte (E) that couples C with G, as well as two power supplies to apply two biases, i.e., V D (between S and D) and V G (between S and G).…”