Flexible point-of-care testing (PoCT) with simultaneous, real-time biomarker monitoring is essential for next-generation wearable health platforms. Here, we present a graphene-printed electrolyte-gated field-effect transistor (EG-GFET) sensing platform fabricated on a flexible polyimide PCB substrate for multiplexed detection of pH, sodium (Na+), and potassium (K+). Graphene ink synthesised via liquid-phase exfoliation was spray-coated to form the active transistor channel. Optimised EG-GFET sensors achieved a pH sensitivity of 25.77 ± 1.42 mV/pH (shift of Dirac point) and 61.59 ± 3.17 μA/pH (modulation of drain current). Ion-selective membranes enabled selective Na+ and K+ sensing with sensitivities of – 61.28 ± 2.95 mV/log10 [Na+] and – 56.09 ± 3.28 mV/log10 [K+], respectively, over linear concentration ranges of 50 μM – 350 mM for Na+ and 50 μM – 150 mM for K+. The flexible devices maintained stable operation under bending angles up to 120°. Real-time dual-analyte experiments further demonstrated simultaneous pH/Na+ and pH/K+ monitoring with minimal observable cross-interference. The platform was further evaluated in acidic and alkaline artificial sweat for pH, Na+, and K+ sensing. These results establish a flexible printed EG-GFET platform for pH and electrolyte sensing in buffer solutions and selected artificial-biofluid matrices.
A Flexible Graphene-Printed Sensing Platform for Real-Time Multi-Analyte Detection of pH, Sodium, and Potassium
Felice Torrisi
Ultimo
2026-01-01
Abstract
Flexible point-of-care testing (PoCT) with simultaneous, real-time biomarker monitoring is essential for next-generation wearable health platforms. Here, we present a graphene-printed electrolyte-gated field-effect transistor (EG-GFET) sensing platform fabricated on a flexible polyimide PCB substrate for multiplexed detection of pH, sodium (Na+), and potassium (K+). Graphene ink synthesised via liquid-phase exfoliation was spray-coated to form the active transistor channel. Optimised EG-GFET sensors achieved a pH sensitivity of 25.77 ± 1.42 mV/pH (shift of Dirac point) and 61.59 ± 3.17 μA/pH (modulation of drain current). Ion-selective membranes enabled selective Na+ and K+ sensing with sensitivities of – 61.28 ± 2.95 mV/log10 [Na+] and – 56.09 ± 3.28 mV/log10 [K+], respectively, over linear concentration ranges of 50 μM – 350 mM for Na+ and 50 μM – 150 mM for K+. The flexible devices maintained stable operation under bending angles up to 120°. Real-time dual-analyte experiments further demonstrated simultaneous pH/Na+ and pH/K+ monitoring with minimal observable cross-interference. The platform was further evaluated in acidic and alkaline artificial sweat for pH, Na+, and K+ sensing. These results establish a flexible printed EG-GFET platform for pH and electrolyte sensing in buffer solutions and selected artificial-biofluid matrices.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
