Modulating Sensitivity of Three-dimensional Graphene Foam-based Strain Sensors through Pre-Stretching

Stretchable electronics advances fields such as wearable health monitoring, soft robotics, and human-machine interface by providing flexible and conformable devices. Graphene, a prominent 2D carbon nanomaterial, is renowned for its exceptional electronic, thermal, and mechanical properties, making it ideal for stretchable electronics. Building on the success of 2D graphene, recent research effort has begun to explore 3D graphene-based foams (GFs), which retain the superior qualities of 2D graphene while offering enhanced multidirectional flexibility. These 3D structures are emerging as promising candidates for stretchable electronic devices, particularly strain sensors, due to their versatile mechanical deformation, and efficient electrical and thermal pathways. Various strategies have been employed to enhance the strain sensing capabilities of GF-based sensors. Our study introduces a straightforward and convenient approach which uses pre-stretching to modulate the sensitivity of these sensors. By applying different levels of pre-stretch strain, we observe variations in sensitivity across specific tensile strain ranges. To elucidate the mechanisms behind this modulation, we propose a model combining density functional theory calculations with Monte Carlo simulations and considering the structural changes in GFs induced by pre-stretching. A thorough understanding of this sensitivity modulation will lead to further optimization of GF-based strain sensors.