A Novel Strategy for Simultaneous Enhancement of Sensitivity and Sensing Range in Crack-Based Sensors via Atomized Liquid Metal Droplets

Although bio-inspired crack-based sensors exhibit ultrahigh sensitivity with gauge factors of ~2,000, their application is limited by a low sensing range (~2%). We propose a novel approach to simultaneously achieve both high sensitivity and an extended sensing range in crack-based sensors by incorporating atomized liquid metal droplets. A crack-based sensor was fabricated by depositing a Cr/Au (0.9 nm/20 nm) metal layer onto O₂ plasma-treated PDMS, followed by the application of mechanical strain to induce a dense network of cracks. Subsequently, atomized liquid metal droplets were coated onto the cracked metal film using an airbrush. Under applied strain, optical images of the crack-based sensor revealed that the atomized liquid metal droplets acted as stretchable conductive bridges across the cracks. Compared to conventional crack-based sensors without liquid metal, the proposed sensor with randomly dispersed liquid metal droplets exhibited not only enhanced sensitivity (gauge factor of ~2,230), but also a significantly improved sensing range—an increase of approximately 366%. The flexibility of the proposed sensor was further validated through repeated tests involving stretching, bending, and twisting.