THz Imaging of Roll Compaction for Pharmaceutical Applications

Abstract

In the pharmaceutical industry, dry granulation is an intermediate state in the tablet manufacturing process for orally administered products. Powder blends with poor flowing properties are compressed and milled producing a granular material with increased flow properties. A key element in the process is the density of the compressed powder since it will affect the final quality of the manufactured tablet.The existing density measurement system employed by AstraZeneca is a destructive measurement. This thesis shows a method for non-destructive density measurements using a terahertz imaging system. A model of the relation between the phase of the THz transmitted signal versus the permittivity of the sample was obtained through fullwave simulations using CST Microwave Studio. By determining the permittivity of samples with known density, a material specific model of how the permittivity varies with density was obtained. The presented density control method has significantly decreased the measurement time by a factor of 2 and it is also capable of measuring the density over a 20 times smaller area of the sample compared with the method currently used at AstraZeneca.