Luminescent Pressure-Sensitive Paints with Embedded Ag@SiO₂ Nanoparticles

Designing pressure-sensitive paint (PSP) to achieve high luminescence and high pressure sensitivity at near-atmospheric pressures increases the signal-to-noise ratio of the luminescence images, facilitating aerodynamic studies of low-speed flows. Here, we investigate a PSP formulation that incorporates silica-coated silver nanoparticles (Ag@SiO2), along with Pt(II) meso-tetra(pentafluorophenyl)porphine (PtTFPP) embedded in a sol–gel matrix. The Ag@SiO2 nanoparticles enhance the luminescence of PtTFPP by localized surface plasmon resonance (LSPR)-induced electric field enhancement rather than through altering the radiative decay rate of PtTFPP. The thickness of the silica layer and the mass ratio of Ag/PtTFPP are essential for optimizing the luminescence enhancement. In comparison to Ag-free PSP, the Ag@SiO2-doped PSP exhibits a 2-fold luminescence enhancement while maintaining a high pressure sensitivity of 0.94%/kPa normalized to atmospheric pressure data. The high luminescence and pressure sensitivity not only offer increased signal strength for imaging low-speed airflows but also hold promising potential for future designs of PSP formulations using MEL.