A bioinspired, paper-based and soft-rigid sensor with wide frequency bandwidth for vibration monitoring

Most equipment or devices generate vibrations when operating, which can serve as a guiding indicator to assess working status. However, the mechanical brittleness and complicated installation process of rigid sensors hinder their applications in structural health monitoring. Thus, flexible vibration sensors with good flexibility, high sensitivity, and the ability to conform easily to curved critical components are in high demand. Here, we demonstrate a highly sensitive flexible, bioinspired paper-based vibration sensor with parallel-crack-designed structures for dynamic vibration monitoring over a wide frequency range. The flexible sensor is designed as a rigid-soft configuration by assembling a stainless steel sheet with a paper layer, which provides sufficient stiffness while maintaining a certain degree of flexibility. By inducing parallel cracks into the surface of MWCNTs/ graphene/PDMS layer-coated paper using femtosecond lasering, the sensor exhibits a high-frequency response of up to 800 Hz, an acceleration response reaching 5 g, good reproducibility, and robust sensing stability. The high sensitivity, wide frequency bandwidth, and flexible format of the paper-based sensor enable it to be directly attached to curvilinear surfaces for in situ vibration sensing, which was demonstrated through the vibration monitoring of mechanical equipment like an electromotor and shield cutter head.