Novel Electrostatic Characterization of Pharmaceutical Powders

Abstract

The triboelectric charging of powders during handling can significantly influence its flow, dose uniformity and in drug inhalation, its dispersion and deposition in the lungs. The Faraday cage is currently the industrial method for bulk powder charge measurements. The aim of this project is to develop alternative techniques to characterize the charge at both single particle and bulk powder levels. A novel, small parallel plate condenser was fabricated and successfully used on the atomic force microscope (AFM) to measure the electrostatic charge of single glass microparticles in an applied electric field. On the other hand, a nonintrusive, vibrating capacitive probe was employed and verified with the Faraday cage to analyse the particle size effects on simulated bulk pharmaceutical powder charging against acetal walls. By combining nonintrusive electrostatic monitoring with high speed imaging, the differences in dynamic charging and impaction behaviours of aerosolized mannitol powders of different surface roughness were evaluated.