Fabrication of Biomass-Based Flexible Sensors by Hydrogen-Bond-Enhanced Epoxidized Natural Rubber

Biomass-based elastomeric materials have been thoroughly researched recently in the area of flexible sensors. Due to its outstanding tensile characteristics, epoxy natural rubber is extremely appealing for applications requiring flexible sensing. However, the poor fracture strength and oxidation resistance ability greatly limit its application. This study found that the introduction of oxidized lignin can greatly improve this bad situation. The maximum elongation improves by 61.51% when the mass ratio of oxidized lignin to ENR is 1:4, and the fracture strength increases by 3.57 times. Furthermore, the material's mechanical performance deterioration was lowered by 38.8% after a month of oxidation at ambient temperature. With exceptional tensile qualities, it was a perfect elastic material for the production of flexible sensors with high sensitivity and large strain. The manufactured flexible sensor performed well, with a linear response of 0.9994 in resistance variation, a quick response (10 ms), durability for over 2000 cycles, and high repeatability for stretching up to 1000%. Such a sustainable biomass-based elastic material, without the need for complex chemical reaction processes and expensive chemical reagents, was anticipated to replace traditional synthetic materials such as silicone rubber and polyurethane in the field of flexible sensor.