Highly sensitive and flexible strain sensor based on Au thin film

Strain sensors used in electronic skins, wearable devices for health monitoring, and implanted devices should have high sensitivity, flexibility, simplicity, and low cost. The fabrication of highly sensitive and flexible nanomaterial-based strain sensors generally requires self-assembly, transfer, and other complex processes. Thus, this study proposed a simple and efficient method for the production of a flexible strain sensor based on Au thin film, which was prepared only through common microfabrication technologies and could realize the mass production of highly sensitive and flexible strain sensors. A transitional Cr layer was fabricated for the improvement of the adhesion force between the Au and polyimide films. Additionally, the gauge factor of the sensor reached 220, and the sensor exhibited good repeatability during the multiple cycle tests. Moreover, the response time of sensor was approximately 300 ms. The high sensitivity was attributed to the combined action of microcrack formation and the size effect of the ultra-thin films, which were characterized through atomic force microscopy and scanning electron microscopy. Because of these excellent properties, this ultrasensitive and flexible strain sensor based on Au thin films has potential applications in electronic skins and wearable devices. (paper)