High-range noise immune supersensitive graphene-electrolyte capacitive strain sensor for biomedical applications.

Area of Science:

• Materials Science
• Electrical Engineering
• Sensor Technology

Background:

• Graphene is widely researched for supercapacitors but underexplored in sensor applications.
• Capacitive sensors often suffer from low base capacitance, limiting their performance.
• Electric double layer capacitance is a key factor in supercapacitor performance.

Purpose of the Study:

• To develop and assess an innovative graphene-electrolyte capacitive sensor (GECS).
• To address the low base capacitance issue in capacitive sensors.
• To explore the potential of GECS in various applications, including biomedical monitoring.

Main Methods:

• Fabrication of GECS using thermally reduced microwave exfoliated graphene oxide for interdigitated electrodes.
• Coating electrodes with a solid-state electrolyte to form electric double layer capacitance.
• Assessing the capacitance response of GECS under strain and evaluating its sensitivity and noise immunity.

Main Results:

• Achieved a million-fold increase in base capacitance (∼22.0 μF) by incorporating electric double layer capacitance.
• Demonstrated an enormous operating range (∼300 nF) and high device sensitivity (11.24 nF kPa-1).
• GECS exhibited good immunity to lead and stray capacitance, with two fabrication-dependent operational regimes identified.

Conclusions:

• The developed GECS offers a significant advancement over traditional capacitive sensors due to its high base capacitance.
• The sensor's performance characteristics make it suitable for a wide range of applications.
• Demonstrated feasibility of GECS for biomedical applications, specifically breath pattern monitoring.