Highly Concentrated, Conductive, Defect-free Graphene Ink for Screen-Printed Sensor Application.

Area of Science:

• Materials Science
• Nanotechnology
• Electrochemistry

Background:

• Graphene conductive inks are crucial for printed and flexible electronics.
• Challenges include mass production and low suspension concentrations of graphene fillers.

Purpose of the Study:

• To develop a scalable fluid dynamics process for producing highly concentrated, defect-free graphene ink.
• To fabricate a flexible electrochemical sodium ion sensor using the developed graphene ink.
• To demonstrate real-time sweat sodium monitoring with a wearable device.

Main Methods:

• High-throughput fluid dynamics for graphene exfoliation and ink formulation.
• Screen printing of graphene conductors and electrochemical sensors.
• Integration with wireless electronics for a wearable sensing system.

Main Results:

• Achieved 53.5% exfoliation yield and 47.5 mg mL^-1 graphene ink concentration.
• Screen-printed graphene conductor showed high electrical conductivity (1.49 × 10⁴ S m^-1) and mechanical flexibility.
• Fabricated electrochemical sodium ion sensor demonstrated excellent potentiometric sensing performance, even when bent.
• Successfully demonstrated real-time sweat sodium ion monitoring using a prototype Na⁺-sensing watch.

Conclusions:

• The scalable fluid dynamics process enables low-cost, reproducible, large-scale production of high-performance graphene ink.
• The developed graphene ink is suitable for fabricating advanced flexible and wearable electronic devices.
• The prototype Na⁺-sensing watch shows potential for continuous health monitoring through sweat analysis.