High sensitivity and wide sensing range graphene flexible strain sensors based on pre-stretching and layer-by-layer self-assembly

In recent years, the development of strain sensors exhibiting heightened sensitivity and an expansive sensing range has emerged as a challenging and pivotal focal point within contemporary research endeavors. The preparation of conductive layers with micro- and nanostructures is a critical trade-off between sensitivity and sensing strain range. This paper presented a novel method for preparing high-performance flexible strain sensors by developing a graphene oxide-based sensor through the integration of layer-by-layer (LbL) self-assembly and pre-stretching techniques. The high sensitivity is due to the cracks created in the conductive layer during pre-stretching, and the wide sensing range is due to the folds formed in the conductive layer as a result of the release of pre-stretching. Additionally, the controllability of LbL deposition enables precise timing for introducing pre-stretching, optimizing the preparation of flexible strain sensors. The optimized pre-stretched GO (PS-GO) sensor features a wide sensing range (0–150 %), high sensitivity (GF=5.9), fast response (192 ms) and good cyclic stability (1000 cycles). Notably, it exhibited a unique signal response when monitoring human motion with varying amplitudes and motions, highlighting its potential applications in smart devices, e-skins, and wearable medical monitors. [Display omitted]