Flexible Textile Strain Sensor Based on Copper-Coated Lyocell Type Cellulose Fabric.

Area of Science:

• Materials Science
• Textile Engineering
• Nanotechnology

Background:

• Integrating sensors into textiles necessitates flexible conductive materials.
• Cellulose-based fabrics offer a promising substrate for conductive coatings.

Purpose of the Study:

• To develop and characterize flexible conductive copper coatings on lyocell fabrics.
• To investigate the conductivity and stability of these coatings under various conditions.

Main Methods:

• Electroless copper coating of woven lyocell fabrics using specific concentrations of copper sulfate, potassium hydrogen tartrate, and formaldehyde.
• Four-probe resistance measurements during cyclic tensile and bending tests.
• Evaluation of resistance changes with wetting/drying cycles and relative humidity variations.

Main Results:

• Copper deposition was found to be diffusion-controlled at high concentrations.
• Conductivity of coated fabrics decreased with elongation (13.2 to 3.7 Ω at 2.2% strain).
• Resistance increased after bending cycles (5.2 to 6.6 Ω) and significantly after wetting/drying (2.6×10^5 fold increase).
• Resistance increased with relative humidity due to fiber hygroscopic expansion (11 to 23 Ω/square from 20% to 80% RH).

Conclusions:

• The study provides insights into conductive copper coating on textiles.
• The developed copper-coated lyocell fabrics demonstrate applicability as flexible strain sensors.
• Understanding the influence of deformation and environmental factors is crucial for sensor performance.