VTT has developed a novel probe technology suitable for real-time process monitoring. The solution is based on VTT's patent-pending integrating sphere technology for optically thin materials. Technology facilitates the whole sample stream to be measured more accurately and more sensitively than with conventional probes. Obvious end-user benefits are in improved process control and quality assurance.
VTT's demonstrator probe utilises near-infrared spectroscopy and its process interface is designed for real-time monitoring of flowing particulate materials. Demonstrations of real-time monitoring of active ingredients in pharmaceutical powders and tobacco have been carried out. In these cases a fourfold increase in the signal-to-noise ratio has been demonstrated, bringing capabilities of NIR process analytics to a new level. The design is also readily compatible with flowing liquids, liquid suspensions and gases, widening the application area to all fluid-handling processes.
The probe is readily available for commercialisation and customer-specific applications, and it goes by the name of NIRSPHERE.
NIRSPHERE uses a flow-through optical cuvette inside an integrating sphere which ensures uniform sample illumination and outstanding light collection efficiency. The spehere design increases the degree of interaction between light and sample, eliminating undesired light scattering effects and providing better sensitivity in the detection of low concentrations.
Depending on the volume and throughput of the powder-handling manufacturing process, the engineering of NIRSPHERE can be scaled up or down. It has been demonstrated that three-dimensional printing is an attractive low-cost manufacturing method for small-scale integrating spheres.
In addition to absorption spectroscopy (in ultraviolet, visible and near-infrared spectral ranges), the benefits of an integrating sphere are also obvious with fluorescence and Raman spectroscopy. The fibre-optic interface makes the NIRSPHERE probe compatible with a wide variety of spectroscopic instruments.
We are keen to offer the NIRSPHERE platform as well as VTT's optical instrumentation development expertise to customers who are interested in developing new advanced process analytics solutions.
Figure 1: The NIRSPHERE probehead, installed at the outlet of a continuous mixer at the PROMIS pharmaceutical continuous manufacturing pilot line at University of Eastern Finland (UEF, Kuopio, Finland). The potential of the NIRSPHERE measurement concept in pharmaceutical powder-handling applications has been extensively tested in research collaboration between VTT and UEF.
Figure 2: The concept of the NIRSPHERE probe.