Two-Dimensional Disposable Graphene Sensor to Detect Na⁺ Ions

Area of Science:

• Materials Science
• Electrochemistry
• Biomedical Engineering

Background:

• Monitoring sodium ion (Na+) levels in the body is crucial for health assessment.
• Current methods often involve indirect measurements or cumbersome procedures.
• There is a need for accurate, disposable, and user-friendly Na+ sensors.

Purpose of the Study:

• To develop a novel disposable sodium ion (Na+) sensor.
• To utilize graphene ion-sensitive field-effect transistors (G-ISFET) and fluorinated graphene reference electrodes (FG-RE).
• To evaluate the sensor's performance in detecting Na+ ions in human urine samples.

Main Methods:

• Fabrication of a two-dimensional (2D) Na+ sensor using G-ISFET.
• Integration of G-ISFET and FG-RE onto a printed circuit board (PCB) in an SD card format.
• Testing sensor sensitivity and linearity in buffer solutions and real human urine samples.

Main Results:

• The G-ISFET sensor demonstrated a sensitivity of -55.4 mV/dec in buffer solutions.
• The sensor showed good linearity and stability in the presence of interfering ions.
• In human urine, the sensor achieved a sensitivity of -0.36 mV/mM, detecting Na+ ions without dilution.

Conclusions:

• A disposable Na+ sensor based on G-ISFET and FG-RE was successfully fabricated.
• The sensor shows potential as a reliable and convenient alternative to traditional Ag/AgCl reference electrodes.
• This technology could advance point-of-care diagnostics for sodium ion monitoring.