Multiaxially-stretchable kirigami-patterned mesh design for graphene sensor devices

In wearable electronics, significant research has gone into imparting stretchability and flexibility to otherwise rigid electronic components while maintaining their electrical properties. Thus far, this has been achieved through various geometric modifications of the rigid conductive components themselves, such as with microcracked, buckled, or planar meander structures. Additionally, strategic placement of these resulting components within the overall devices, such as embedding them at the neutral plane, has been found to further enhance mechanical stability under deformation. However, these strategies are still limited in performance, failing to achieve fully strain-insensitive electrical performance under biaxial stretching, twisting, and mixed strain states. Here, we developed a new platform for wearable, motion artifact-free sensors using a graphene-based multiaxially stretchable kirigami-patterned mesh structure. The normalized resistance change of the electrodes and graphene embedded in the structure is smaller than 0.5% and 0.23% under 180° torsion and 100% biaxial strain, respectively. Moreover, the resistance change is limited to 5% under repeated stretching-releasing cycles from 0% to 100% biaxial strain. In addition, we investigated the deformation mechanisms of the structure with finite element analysis. Based on the simulation results, we derived a dimensionless geometric parameter that enables prediction of stretchability of the structure with high accuracy. Lastly, as a proof-of-concept, we demonstrated a biaxially-stretchable graphene-based sensor array capable of monitoring of temperature and glucose level with minimized motion-artifacts.