Visualization of Protein Network Mechanical Heterogeneity Using Ultrasound-Coupled Microcavity Lasers

Whispering-gallery-mode (WGM) microcavities are emerging as a powerful tool for investigating the mechanical properties of biological systems. However, the wavelength shifts in WGM spectra reveal overall phase change, making it difficult to resolve localized mechanical heterogeneity. Here, we developed a laser-emission imaging approach that integrates ultrasound stimulation with WGM microcavities, enabling spatially resolved and quantitative mapping of microscopic mechanical properties in protein networks. The time-resolved lasing spectra were found to correlate with the ultrasound-driven mechanical vibrations, which were subsequently used to quantify localized mechanical responses. By reconstructing 3D correlation cubes at different positions on the protein network through stage scanning, we achieved spatial mapping of the evolving mechanical heterogeneity during crosslinking. Moreover, high-throughput monitoring of mechanical variations across multiple samples was successfully demonstrated. Our work establishes a new platform that couples optical and acoustic interactions at the microscale, enabling rapid quantification of the dynamic mechanical behaviors of soft biomaterials.