Particle size and shape effects in medical syringe needles: experiments and simulations for polymer microparticle injection.

Injection of polymeric microparticles is the final step in the drug delivery process. Experience has shown that blockage of the syringe mechanism can be a problem under certain conditions leading to poor control of the final product. Particle size and shape are postulated to be significant factors. In this article 2D Discrete element model (DEM) simulations of circles and semi-circles are used to demonstrate the effect of shape on blockage of the syringe mechanism. To corroborate the calculations, a range of experiments on glass spheres and polymers show good agreement with simulations of normally distributed particle sizes. A similar scenario is also briefly modelled in 3D DEM showing similar trends.