Enhanced Sensitivity in Crack-Based Graphene Nanoplatelets Strain Sensors

Crack-based strain sensors have emerged as promising candidates for applications requiring high sensitivity and ultralow strain detection. The integration of nanomaterials with cracked polymer substrates offers a viable pathway to fabricate flexible, ultrasensitive sensors capable of detecting minute mechanical deformations. In this study, we present a strain sensor composed of a polydimethylsiloxane (PDMS) substrate and graphene nanoplatelets (GNPs), in which the GNP flake size is precisely controlled to optimize the sensor performance. The resulting sensor exhibits an ultrahigh gauge factor of 320 at 0.01% strain and an ultrahigh gauge factor of 4200 at 10% strain, achieving both ultrahigh sensitivity and acceptable stretchability. <i>In situ</i> SEM deformation characterization revealed that the sensitivity of the sensors is strongly dependent on the relative dimensions of the GNP flake size and crack width. In addition, the sensor demonstrated excellent durability under 1000 loading cycles, confirming its reliability for repeated use. Demonstrated applications include sound recognition and strain monitoring of metallic components operating within the elastic regime under tensile stress.