A mechanochromic optical sensor based on Bragg reflection for real-time monitoring of large-range sharp pressure fluctuations in aqueous fluids

In recent years, mechano-actuated sensors have received extensive attention due to their excellent sensitivity in the dynamic pressure and flow field. In this study, a mechanochromic optical sensor based on Bragg reflection was fabricated, which can realize ultra-fast real-time monitoring of large-range sharp pressure fluctuations. To enhance environmental adaptability, the effects of concentration and zeta potential on the optical properties of a NPC hydrogel were discussed, and the hydrogel was integrated with polydimethylsiloxane and graphene oxide as sensors. The reflection peak of the NPC hydrogel shifted from 633 nm to 397 nm and the structural color changed from red to blue at 173 kPa. The optical sensor was designed with maximum measuring ranges of 407.1 kPa, 1.59 MPa, 4.15 MPa, 9.52 MPa and 15.50 MPa and their feasibility was verified by cavitation. Simulation and actual monitoring results showed that the sensors can realize the real-time monitoring of large-range sharp pressure fluctuations in aqueous fluids, their structural color can be changed in ultrafast conversion and recovery within 0.0001 s, and the spatial resolution was 0.21 mm. This work provides a novel strategy for real-time monitoring of large-range sharp pressure fluctuations in aqueous fluids, which created a precedent for ultra-fast visual monitoring of large-scale and dramatic pressure fluctuations.