Low-cost microarray thin-film electrodes with ionic liquid gel-polymer electrolytes for miniaturised oxygen sensing

Area of Science:

• Electrochemistry
• Materials Science
• Sensor Technology

Background:

• Electrochemical sensors are crucial for gas detection.
• Developing miniaturized and robust sensors is an ongoing challenge.
• Ionic liquids and polymers offer potential for advanced electrolyte materials.

Purpose of the Study:

• To construct and characterize a miniaturized electrochemical gas sensor for oxygen (O2).
• To evaluate the performance of a novel gel electrolyte composed of room temperature ionic liquid (RTIL) and poly(methyl methacrylate) (PMMA).
• To determine the optimal sensing technique for different oxygen concentration ranges.

Main Methods:

• Fabrication of a sensor using a platinum (Pt) microarray thin-film electrode (MATFE) and a PMMA/RTIL gel electrolyte.
• Characterization of oxygen diffusion and solubility in PMMA/RTIL mixtures using potential step chronoamperometry (PSCA).
• Analysis of sensor performance using cyclic voltammetry (CV) and long-term chronoamperometry (LTCA) across a wide O2 concentration range.

Main Results:

• The PMMA/RTIL gel electrolyte demonstrated improved stability and reduced potential shifting compared to neat RTIL.
• LTCA proved more reliable for low O2 concentrations (<0.5% O2), while CV was better for high concentrations (>60% O2).
• The sensor showed viability for bulk-scale oxygen detection under diverse environmental conditions.

Conclusions:

• A robust, miniaturized electrochemical oxygen sensor was successfully developed.
• The PMMA/RTIL gel electrolyte enhances sensor stability for long-term monitoring.
• The low-cost, mass-producible sensor is suitable for widespread oxygen detection applications.