Mechanofluorochromic Material toward a Recoverable Microscale Force Sensor

Among the multiple classes of mechanofluorochromic (MFC) compounds reported in recent years, simple donor–acceptor molecules involving oligooxyethylene N-substituted diphenylamine connected to a dicyanovinyl group by thienyl spacer constitute specific class mechano-stimulable smart materials with unique combination properties including turn-on mechanofluorochromism red-light photoluminescence emission, turn-off second harmonic generation, and self-recovery ambient conditions. While dynamics MFC processes thin films these have already been investigated, correlation behavior observed at macroscale elemental taking place micro- nanoscopic scales remains largely unexplored. In this work, atomic force microscopy (AFM) coupled wide-field confocal optical microscopies is used investigate turn-on/recovery microcrystals nanostructures. It shown that red light nano-objects can be turned-on contact AFM intensity emission linearly correlated applied nominal force. Recovery associated decrease intensity, which reactivated again subsequent scans. These results thus pave way toward development micro-/nanoscale recoverable force-sensing technologies based on particular molecular materials.