A flexible metal thin film strain sensor with micro/nano structure for large deformation and high sensitivity strain measurement.

• A micro/nano bulge and crack structures were fabricated to improve the sensitivity and measurement range of the sensor. • A simple tear and stick method was proposed to obtain micro/nano structures. • The measurement range of the flexible sensor can be up to 80% and maximum sensitivity is 20. • The flexible sensor can perform real-time monitoring of human joint motion. [Display omitted] Flexible strain sensors have been garnering substantial attention since being proven to be an effective means to acquire critical biomarkers for monitoring the states of the movement of organisms. This work introduces a flexible metal thin film strain sensor with micro/nano structure which has large measurement range and high sensitivity strain measurement. The large measurement range can be realized by the bugles that avoiding expanding of cracks and the high sensitivity is attributed to the disconnection-reconnection process by nanoscale cracks. In experiments, a flexible strain sensor with 30 nm Au nano-film was researched, and the results show that the maximum strain measurement range of the Au nano-film flexible sensor with micro/nano bulge structure can reach to 80%, and the gauge factor (GF) can reach to 20. In addition, the good repeatability and stability were proved by more than 1000 times cycles. Finally, this flexible sensor was attached to human's fingers for real-time monitoring of the state of human joints and was demonstrated to have good comprehensive performance and usability. These features create opportunities for applying in many fields like wearable medical devices, e-skin, flexible robots and so on. [ABSTRACT FROM AUTHOR]