Dr. Axel Zeitler
Department of Chemical Engineering & Biotechnology, University of Cambridge

We present terahertz pulsed imaging (TPI) as a novel tool to quantify the hardness and surface density distribution of pharmaceutical tablets. Good agreement between the surface refractive index (SRI) measured by TPI and the crushing force measured from diametral compression tests (DCT) was found using a set of tablets that were compacted at various compression forces. We also found a strong correlation between TPI results and tablet bulk density, and how these relate to tablet hardness. Numerical simulations of tablet surface density distribution by finite element analysis (FEA) exhibit excellent agreement with the TPI measured SRI maps. These results show that TPI has an advantage over traditional diametral compression and is more suitable for non-destructive hardness and density distribution monitoring and control of pharmaceutical manufacturing processes. In this presentation I will also highlight potential developments how this novel technology could be moved toward in-die analysis.