Instrumentation of a high-shear mixer: evaluation and comparison of a new capacitive sensor, a watt meter, and a strain-gage torque sensor for wet granulation monitoring.

A high-shear mixer was instrumented with a new capacitive sensor, a watt meter, and a strain-gage torque sensor. The output from the capacitive sensor was split into two channels, which monitor both resistive and capacitive changes during the granulation process. The outputs of the devices were related to properties of the wet granulation. The percentage moisture content related linearly to the amplitude channel response. Yield values provided a rheological property to relate with power consumption and torque measurement. Power consumption and torque furnished a similar map of the granulation process. The amplitude channel of the capacitive sensor appears to be more clearly differentiated between binder levels in hydrous lactose-HPMC granulations than either power consumption or torque measurement, based on particle size distributions.