Sensitivity enhancement of potassium ion (K+) detection based on graphene field-effect transistors with surface plasma pretreatment

Abstract

Potassium (K+) ions are essential minerals that are important in maintaining fluid and electrolyte balance in biological systems and regulating bodily functions. However, abnormal K+ concentration level will cause numerous health problems or diseases. Therefore, the effective detection of physiological K+ level is very important in the healthcare field. In this work, we designed, fabricated and characterized solution-gated field effect transistors (FETs) based on high quality CVD graphene for highly sensitive and selective detection of K+ ions. O2 plasma pre-processing for 10 s yielded a limit of detection (LOD) down to 0.058 pM, and a linear dynamic range spanning from sub-0.1 pM to 100 nM. Meanwhile, as the G-quadruplex conformation possesses strong affinity for K+, the FETs exhibit excellent discrimination against other common cations, such as Na+ and Fe3+. As a result, the solution-gated graphene FETs with enhanced sensitivity and selectivity for K+ can be applied to health monitoring and disease prevention.