Visualising liquid transport through coated pharmaceutical tablets using terahertz pulsed imaging

Terahertz pulsed imaging (TPI) was used to visualise the live liquid penetration process of coated pharmaceutical tablets. Multiple features are observed including diffusion through both coating and core layer, with a discontinuity at the core-coating interface as well as the dissolution of the interface. They can all be conveniently quantified, compared and related back to processing parameters such as porosity of the core and other results from the THz scan. This study establishes a methodology of using TPI to quantitatively analyse the process of liquid penetration through tablet coating. The technique has demonstrated ability to differentiated stages of flow across sub-millimeter distance at sub-second time resolution. The analysis also shows potential to build up synergy with porosity measurement with THz-TDS and the robotic TPI scanning system.