High-stability flexible strain sensors for smart compression garments: Influence of design and fabrication techniques

Compression garments are mostly used in sports and medical applications to apply controlled pressure on the body. Conventional strain sensors were rigid, which limited integration and their flexibility. Recently many flexible strain sensors were developed, however, they have not succeeded in sustaining continuous conductivity due to the displacement of conductive particles or the formation of microcracks that disrupt the conductive pathway. The aim of this research is to fill that gap by investigating the flexible strain sensors that have stable signal performance and greater durability. In this study sensors were developed by two fabrication techniques and two levels, using conductive silver-based ink. The resulting sensors were characterized by electrical resistance, strain, bending, abrasion and washing durability to simulate real usage conditions. In results design B (crisscross pattern), with knife coating (technique K) at level 2, showed the most efficient, consistent, and had great stability under strain in terms of conductivity and durability. Design B had more connecting points with very short distance between endpoints, which minimized the impact of any defects and disruption outside the endpoints. In DIW printing (technique P), uneven surface of substrate disturbed the printing nozzle movement that compromised the printing evenness and overall sample quality. Finally, best performed sensor was integrated into the compression garment for real-time monitoring.