Design and Implementation of Microwave Sensors
Using COMSOL multiphysics simulation software, Purdue University researchers with the NSF-funded Engineering Research Center (ERC) for Structured Organic Particulate Systems (C-SOPS), based at Rutgers University, have designed two novel microwave sensors that can be used to monitor bulk density and moisture content in rapidly flowing powders with a high degree of accuracy. The sensors better support continuous manufacturing processes for the pharmaceutical industry.
The C-SOPS microwave sensors are able to monitor moisture content, mass flow rate, and material composition with comparable accuracy to commercially applied near-infrared (NIR) probe sensors. The microwave sensors further alleviate common drawbacks of NIR probes like poor sample penetration and the need for complex chemometric software in pharmaceutical manufacturing.
The C-SOPS team conducted powder characterization studies to correlate the new microwave sensors’ measurements. The novel sensor design proved highly effective and accurate in measuring ribbon density. It also performed better than NIR probe sensors in sampling the complete ribbon content, rather than only sampling at specific locations along the ribbon. Although the microwave sensors can be used to monitor bulk density and moisture content in rapidly flowing powders with a high degree of accuracy, they are not designed for monitoring highly bound water, such as water of crystallization, when only using a single resonant frequency.
