Facile fabrication of sensitivity-tunable strain sensors based on laser-patterned micro-nano structures

Flexible/stretchable electronics have been well-developed in epidermal devices, wearable electronic systems and soft robotics for physiological signal detecting, real-time health monitoring and human-machine interfaces. As one of the most widespread-used transducers, strain sensors are playing a promising role in the developments of ongoing flexible electronics, especially equipped with tunable sensitivity (or gauge factor, GF). However, present investigations mainly focus on the enhancement of the sensitivity which required subtle designs or sophisticated fabrication processes. In this work, we report a facile fabrication strategy for configuring strain sensors with tunable sensitivity by adjusting the orientations and duty ratios of the micro-nano hierarchical Ag-coated microgrooves from laser patterning. The heterogeneous micro-nano structures enable localized large deformation to result in crack propagation on electrical layer during stretching, which endows the device with customized GF from 3.4 to 4570.6. The sensitivity-tunable strain sensor shows a great potential in monitoring various health conditions and voice recognition. This technique provides a facile and robust way to fabricate high-performance strain sensors for wearable physiological monitoring systems.