Research > Faculty Projects

Non-destructive Measurement of Moisture Distribution with Fringing Electric Field Sensors

Principal Investigator
Alexander Mamishev

Sponsor(s)
Center for Process Analytical Chemistry (CPAC)

Award Period
07/01/1994 - 12/31/2008

Abstract
Measurement of moisture concentration in the bulk of solid materials is an omnipresent need in industries that involve polymers, forest products, chemicals, and foods. Most industrial applications require on-line non- destructive measurements for control of manufacturing processes and evaluation of aging status. The proposed work will continue development of novel versatile measurement approach that allows real-time evaluation of spatial moisture distribution in solid and viscous materials. The approach is based on multiple penetration depth fringing electric field (FEF) dielectric spectroscopy sensors. Major advantages of this measurement technique include one-sided access to material under test, profiling and imaging capabilities, and model-based signal analysis. The sensors use variable excitation frequency to obtain dielectric spectrum of material under test. Sensor array output signal can be converted into such physical variables as moisture, porosity, density, structural integrity, thickness of layers, degree of cure, and surface roughness. Moisture distribution is the primary emphasis of this project.

The project will result in the development of instrumentation and algorithms for measurement of moisture concentration with spatial resolution ranging from 50 microns to 5 centimeters. Monitoring of moisture dynamics processes in real time will be coupled with diffusion process simulations to provide reliable input data for process control instrumentation. The project will involve extensive testing and improvement of recently designed and fabricated fringing electric field sensor arrays, signal conditioning, interfacing with commercially available state of the art high-speed data acquisition hardware, and development of signal processing software. As a result, CPAC members will be able to measure moisture distribution in their products in real time. The prime focus products for the proposed time period are expected to be paper and dough. Experiments in manufacturer's facilities on actual production systems will take place in the beginning of 2002.

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