(661d) Development of a Novel Microwave Sensor for Improved Process and Quality Control

Authors: 
Austin, J. S. III, Purdue University
Harris, M. T., Purdue University
Gupta, A., Purdue University
Reklaitis, G. V., Purdue University



Process analytical technologies play a key role in many solids manufacturing industries.  With the advent of the FDA’s PAT initiative, analytical methods are becoming increasingly important in the pharmaceutical industry as well.  Commonly, solids engineers turn to near infrared spectroscopic techniques to meet their PAT needs.  Although NIR spectroscopy is a powerful sensing platform, it suffers from several significant drawbacks.  Most notably, an NIR sensor can only monitor the material properties of the first few millimeters of a sample.  This can be a substantial drawback in wet granulation and other unit operations where caking over the sensor can occur.  In addition, NIR sensor calibrations do no transfer between formulations and are sensitive to many physical as well as chemical properties.  Furthermore, NIR sensors require complex chemometric software and trained technicians to operate them.  Microwave sensing promises a viable alternative that does not suffer from these significant drawbacks.

The introduction of microwave sensors to solids processing has mostly been driven by a desire to monitor either the moisture content or the density of a material.  While on-line microwave sensors excel when used to monitor these properties, there has been little effort to expand their capabilities.  In this study, a novel microwave sensor was designed to investigate the feasibility of monitoring other material properties, such as material composition.  Furthermore, the design of this sensor allowed material properties to be monitored spatially across a particulate material.