Mechanochemical Stress Sensing

Abstract

Classical mechanochemical kinetics do not explain the persistent and history-dependent fluorescence patterns observed in spiropyran (SP) to merocyanine (MC) transitions within elastomers. This thesis addresses this gap by developing a dual-imaging methodology that integrates Digital Image Correlation (DIC) with fluorescence imaging to establish a reproducible correlation between local strain fields and mechanophore activation. The approach employs synchronized acquisition under alternating green and near-infrared illumination, enabling co-registered speckle and fluorescence images at identical mechanical states. A custom-built hardware and software was implemented, combining automated stage control, LED modulation, and image capture within a unified interface. This framework ensures temporal and spatial alignment, while allowing full-field strain analysis and fluorescence quantification across identical deformation steps. The developed methodology demonstrates that fluorescence activation systematically coincides with regions of strain localization. While low-strain sensitivity is constrained by illumination artifacts, the integrated imaging provides robust quantitative correlations at higher strains. Beyond the immediate results, the framework establishes a transferable platform for testing mechanophores as molecular stress sensors, with applications in diagnostics, materials design, and the broader study of mechanochemistry in soft matter.