Multi-Modal Luminescent Paint Systems for Underwater Surface Diagnostics

STTR topic DON27TZ02-NV007 (U.S. Department of Defense – Navy), Phase I and II. Open to U.S. small businesses; STTR projects partner with a U.S. research institution. Opens: December 2, 2026. Closes: January 6, 2027. Quantifying coupled boundary layer interactions along hydrodynamic surfaces require non-intrusive, full-field imaging of surface pressure, temperature, and skin friction (shear stress). While optical diagnostics have revolutionized aerodynamic testing, adapting luminescent paints to hydrodynamic testing in water introduces fundamental physical and application constraints that current state-of-the-art systems cannot overcome: • Pressure-Sensitive Paint (PSP): Conventional PSP relies on oxygen-quenching physics. When submerged, oxygen diffusion into the polymer binder is severely inhibited by the liquid boundary layer and low oxygen solubility, rendering standard PSPs insensitive or plagued by extremely slow response times. Furthermore, severe temperature cross-sensitivity corrupts the pressure signal. • Temperature-Sensitive Paint (TSP): Accurate dynamic temperature measurements are crippled by the standard utilization of Taylor’s frozen-flow hypothesis, which inaccurately assumes turbulent structures remain unchanged as they advect. In water, non-equilibrium flow, high thermal mass and rapid localized diffusion cause this hypothesis to break down, failing to capture true high-frequency temperature fluctuations. • Mechano-Luminescent Paint (MLP): MLPs offer a direct optical pathway to map shear stress via mechanical deformation. However, current MLP formulations are in their technological infancy, suffering from poor dynamic range, low luminous efficiency, and signal degradation from material fatigue and hydrostatic pressure cross-talk. In addition to the above challenges, current formulations are difficult to apply uniformly over large areas. Existing techniques fail to maintain a consistent, repeatable coating thickness on complex,…