Dr Sarah Rough

Photo of Dr Sarah Rough

MEng, MA (Cantab), PhD (DIC)

Ext. Director of Studies
MPhil ACE Programme Manager, Departent of Chemical Engineering


Dr Rough has been teaching and researching within the Department of Chemical Engineering since the late 1990s. She is also the Programme Manager for the M.Phil. in Advanced Chemical Engineering.


My current main research interests lie in the processing of stiff pastes. The majority of my work focuses on the extrusion-spheronisation of pharmaceutical pastes. Many pharmaceutical drugs are administered in the form of a controlled release dose. An effective way of achieving this is by using spherical pellets (about 1 to 2 mm in diameter) of powder/binder. The spheres consist of an excipient, such as lactose or microcrystalline cellulose, and are coated with or contain a small amount of active ingredient. These spheres can be subsequently pressed into tablets or filled into capsules for oral administration. The spheres are usually produced via paste extrusion-spheronisation. Extrudates obtained from a screen extruder are loaded onto a rotating frictional plate and the paste segments are thus broken up and rounded into spherical pellets. It is important that well-formed spheres of narrow size distribution are generated in order to achieve product dose uniformity and reproducibility.

My current research looks at the effect of paste preparation and extrusion-spheronisation processing conditions on the mechanism of pellet formation for water-based microcrystalline cellulose (MCC) pastes. The work investigates the parameters that affect the morphology, size and size distribution of the spheronised pellets.


  • extrusion
  • spheronisation
  • Paste
  • powder

Key Publications

Rough, S.L., Bridgwater, J. and Wilson., D.I. (2000) Effects of liquid phase migration on extrusion of microcrystalline cellulose pastes Int. J. Pharm., 204, 117-126.

Rough, S.L. and Wilson, D.I. (2005) Extrudate fracture and spheronisation of microcrystalline cellulose pastes J. Mat. Sci., 40, 4199-4219.

Wilson, D.I. and Rough, S.L. (2007) Extrusion-Spheronisation In “Granulation and Coating of Fine Powders”, AD Salman et al. (Eds.), Elsevier.

Parkin, J., Widjaja, K.S., Bryan, M.P., Rough, S.L. and Wilson, D.I. (2016) Experimental validation of a dimensional analysis of spheronisation of cylindrical extrudates, Powder Tech., 298, 73-83.