Hand-drawn electrode based disposable paper chip for artificial sweat analysis using impedance spectroscopy

Area of Science:

• Materials Science
• Analytical Chemistry
• Biomedical Engineering

Background:

• Paper-based electrical sensors are crucial for environmental and healthcare applications, but often suffer from high electrical double-layer capacitance.
• Sophisticated instruments are typically required for electrode patterning, limiting accessibility.
• Direct contact between analyte solution and electrodes leads to capacitance issues in conventional designs.

Purpose of the Study:

• To develop a low-cost, disposable paper-based electrical sensor with reduced double-layer capacitance.
• To enable impedimetric sensing of ionic concentration using minimal sample volumes (microliters).
• To explore the use of hand-drawn electrodes on the reverse side of paper for improved sensor design.

Main Methods:

• Fabrication of hand-drawn electrodes on the reverse side of paper to act as sample storage.
• Utilizing impedimetric sensing for ionic concentration analysis of microliter sample volumes.
• Analyzing the interaction of graphite and silver electrodes with varying electrolyte volumes and concentrations.
• Visually monitoring droplet formation to minimize sample wastage.

Main Results:

• A reduction in electrical double-layer effect was observed with low sample volumes.
• The silver electrode paper chip demonstrated enhanced impedance stability compared to the graphite electrode chip.
• The sensor successfully detected varying ionic concentrations in artificial sweat samples.
• The hand-drawn electrode design effectively reduced double-layer capacitance.

Conclusions:

• The proposed paper-based sensor offers a robust and sensitive method for analyzing ionic concentrations.
• The novel design minimizes sample volume requirements and reduces measurement errors.
• Paper-based diagnostic sensors hold significant potential for disposable healthcare applications.