Development and optimization of an LED–based particle image velocimetry methodology for dynamic powder flowability in pharmaceutical manufacturing

Conventional static flowability tests lack the sensitivity to capture process–relevant powder dynamics. This study developed and optimized an LED–based particle image velocimetry (PIV) system for real–time, non–invasive characterization of powder dynamic flowability during blending. Three PIV parameters, illumination intensity, CLAHE window size, and interrogation window size, were systematically optimized; optimal conditions (65,125 lx; 16 px CLAHE; 32 px) yielded reproducible velocity vector fields. The system was applied to six excipients: three MCC grades (Avicel® PH–102, PH–112, PROSOLV® SMCC 50) and three lactose–based powders (Cellactose® 80, Tablettose® 80, MicroceLac® 100), with complementary FT4 powder rheometer measurements. Multi–parametric analysis encompassing velocity magnitude, vorticity, shear strain rate, stretching deformation rate, and correlation coefficient across spatially defined regions of interest revealed powder–specific flow dynamics. Among MCC grades, PROSOLV® SMCC 50 showed the highest velocity (0.99 px/frame), while Avicel® PH–102 and PH–112 were comparable (0.32 px/frame each) yet differed 6–9–fold in blade–region vorticity and shear strain rate, representing mechanistic differences not discernible by static Carr’s index. Among lactose–based powders sharing similar static classifications, PIV revealed distinct velocity profiles: MicroceLac® 100 (0.78), Cellactose® 80 (0.71), and Tablettose® 80 (0.51 px/frame). FT4 cohesion and unconfined yield strength inversely correlated with PIV velocity (r = −0.97), corroborating the PIV–derived flowability rankings, whereas basic flowability energy did not predict blending performance, confirming that confined–condition metrics do not capture process–relevant dynamics. These results establish LED–based PIV as a practical, multi–dimensional flowability characterization tool, complementary to powder rheometry, with direct relevance to excipient selection and process design in pharmaceutical manufacturing.