posted on 2022-08-08, 15:20authored byTing Li, Jie Yan Cheryl Koh, Akshay Moudgil, Huan Cao, Xihu Wu, Shuai Chen, Kunqi Hou, Abhijith Surendran, Meera Stephen, Cindy Tang, Chongwu Wang, Qi Jie Wang, Chor Yong Tay, Wei Lin Leong
Organic electrochemical transistors (OECTs) have recently
attracted
attention due to their high transconductance and low operating voltage,
which makes them ideal for a wide range of biosensing applications.
Poly-3,4-ethylenedioxythiophene:poly-4-styrenesulfonate (PEDOT:PSS)
is a typical material used as the active channel layer in OECTs. Pristine
PEDOT:PSS has poor electrical conductivity, and additives are typically
introduced to improve its conductivity and OECT performance. However,
these additives are mostly either toxic or not proven to be biocompatible.
Herein, a biocompatible ionic liquid [MTEOA][MeOSO3] is
demonstrated to be an effective additive to enhance the performance
of PEDOT:PSS-based OECTs. The influence of [MTEOA][MeOSO3] on the conductivity, morphology, and redox process of PEDOT:PSS
is investigated. The PEDOT:PSS/[MTEOA][MeOSO3]-based OECT
exhibits high transconductance (22.3 ± 4.5 mS μm–1), high μC* (the product of mobility μ and volumetric
capacitance C*) (283.80 ± 29.66 F cm–1 V–1 s–1), fast response time (∼40.57
μs), and excellent switching cyclical stability. Next, the integration
of sodium (Na+) and potassium (K+) ion-selective
membranes with the OECTs is demonstrated, enabling selective ion detection
in the physiological range. In addition, flexible OECTs are designed
for electrocardiography (ECG) signal acquisition. These OECTs have
shown robust performance against physical deformation and successfully
recorded high-quality ECG signals.