Multiscale Structural Control by Matrix Engineering for Polydimethylsiloxane Filled Graphene Woven Fabric Strain Sensors

Elastomer cure shrinkage during composite fabrication often induces wrinkling in conductive networks, significantly affecting the performance of flexible strain sensors, yet the specific roles of such wrinkles are not fully understood. Herein, a highly sensitive polydimethylsiloxane-filled graphene woven fabric (PDMS-f-GWF) strain sensor by optimizing the PDMS cure shrinkage through careful adjustment of the base-to-curing-agent ratio is developed. This sensor achieves a gauge factor of ∼700 at 25% strain, which is over 6 times higher than sensors using commercially formulated PDMS. This enhanced sensing performance is attributed to multiscale structural control of the graphene network, enabled by precisely tuned cure shrinkage of PDMS. Using in situ scanning electron microscopy, X-ray scattering, and Raman spectroscopy, an optimized PDMS base-to-curing-agent ratio of 10:0.8 is show that enables interconnected structural changes from atomic to macroscopic scales, including larger "real" strain within the graphene lattice, enhanced flattening of graphene wrinkles, and increased crack density. These findings highlight the critical role of elastomer shrinkage in modulating the multiscale structure of conductive networks, offering new insights into matrix engineering strategies that advance the sensing performance of elastomer-based flexible strain sensors.