Stereo Vision Probe: A New PAT Instrument for Real-time Characterisation of Particulate Systems

Research on particle shape is extremely important to many industrial applications such as pharmaceuticals, biopharmaceuticals, human health products and speciality chemicals. For example, for pharmaceuticals, the morphology can affect important properties such as dry powder density, cohesion, and flowability, that can have major impact on a company's ability to formulate drug particles into finished products. Moreover, crystal morphology can affect drug dissolution, potentially affecting formulated product bioavailability and, in extreme, resulting in a companies loss of the license to making the drug product. However, despite the availability of various Process Analytical Technology (PAT) instruments for measuring other properties of particulate systems, there have been no effective on-line instruments capable of providing real-time information on particle shape during the processing of particles in unit operations such as crystallisation, precipitation, granulation and milling. In the past few years, on-line high speed imaging has shown to be a very promising PAT instrument for real-time measurement of particle shape on-line which has resulted in the development of some new instrumentation products just released to the market such as the PVM (Process Vision system) of Lasentec (uk.mt.com), the PIA (Process Image Analyser) of MessTechnik Schwartz GmbH (www.mts-duesseldorf.de), the ISPV (In-Situ Particle Viewer) of Perdix (www.perdix.nl) in Netherlands, and the On-line Microscopy systems of GlaxoSmithKline, some of which incorporate a probe design which allows easy access to a processing reactor vessel. However, all these techniques are essentially limited in that they can only provide 2D information of the particle shape. Hence, this proposed research aims to develop a new instrument Stereo Vision Probe which can directly image the full 3D shape of particles within a practical processing reactor. This basic mode of operation is based on the mathematical principle that if the 2D images of an object are obtained from two different angles, the full 3D particle shape can be recovered. The potential impact on research capability and industrial applications is predicted to be major but the proposed research will focus on the development of the Stereo Vision Probe and the 3D construction method from the two 2D images obtained from two different angles. The testing of the system will be mainly via the use of a variable temperature crystallisation cell.