Patterning of graphene for highly sensitive strain sensing on various curved surfaces

In recent years, graphene based flexible strain sensors have attracted great attention. Although various designed micro/nanostructure morphologies have been introduced to optimize the performance parameters such as sensitivity and working range, there are relatively limited studies on the effective patterning of graphene on various substrates on curved surfaces to manufacture functional devices. In this work, we report a general route to realize the patterning of graphene into predesigned structure on a variety of complex curved substrates. The methodology involves a combination of polydopamine surface modification of the substrate and the spraying process of graphene. The polydopamine modification method preserves the intrinsic electrical properties and stability of graphene, and the modification process by self-polymerization of dopamine is available on many types of materials of complex shape. This general approach of interface modification to achieve free patterning has capability of large-scale fabrication. By this interface-enhancement patterning method, sensing structure of cut-through channel crack has been obtained, resulting in flexible strain sensors with adjusted high sensitivity (gauge factor of 100-2000 at 1% strain), little hysteresis and conformality of complex surfaces. In addition, the strain sensor array has also been fabricated to detect the deformation spatial distribution of complex curved structural components, thereby expanding their potential applications in wearable electronics.