Preparation of Gradient Polyurethane and Its Performance for Flexible Sensors

Area of Science:

• Materials Science
• Polymer Science
• Sensor Technology

Background:

• Flexible sensors often suffer from slow recovery and significant residual strain, limiting their practical use.
• Existing flexible sensor materials struggle to balance mechanical properties with rapid response and minimal deformation.
• The development of advanced materials is crucial for overcoming these limitations in wearable electronics.

Purpose of the Study:

• To develop a novel flexible sensor material with an enhanced recovery rate and reduced residual strain.
• To investigate the effect of a gradient elastic modulus in polyurethane composites on sensor performance.
• To explore the potential of these gradient materials for applications in wearable skin motion and health monitoring.

Main Methods:

• Synthesized gradient polyurethane structures by varying hard and soft segment ratios.
• Incorporated flake silver powder to achieve conductive properties, determining the percolation threshold.
• Fabricated and tested gradient polyurethane composites for mechanical and sensing properties, including recovery rate, residual strain, and fatigue resistance.

Main Results:

• Gradient polyurethane composites demonstrated improved recovery rates and reduced residual strain compared to non-gradient materials.
• The conductive percolation threshold was identified between 45 wt% and 50 wt% silver powder.
• Tested composites exhibited excellent fatigue resistance over 1000 cycles and stable electrical responses.
• Achieved high sensitivity coefficients (1.20 at 0-25% and 11.38 at 25-75% deformation).

Conclusions:

• Gradient polyurethane composites offer a promising solution for flexible sensors requiring high recovery rates and low residual strain.
• The developed material exhibits robust mechanical and electrical properties suitable for demanding applications.
• This technology has significant potential for advancing wearable skin motion detection and health monitoring systems.