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Contact-less millimetre-wave based sensor with enhanced sensitivity for inline extraction of food properties during a production process Host Publication: 30th EFFoST International Conference Authors: G. Pandey, W. Vandermeiren, L. Dimiccoli and J. Stiens Publication Date: Nov. 2016
Abstract: Introduction: Millimetre (mm) waves typically offer a good compromise between lateral resolution and penetration depth in matter like food. These qualities make high sensitive mm-wave based sensors a good choice for food processing applications to monitor the food quality and to reduce the processing costs. Electromagnetic wave based sensors exploit the reflection and transmission/absorption spectra of food to extract different food properties like ice or moisture content, temperature, density and volumetric fraction of constituents of the food under consideration. These parameters of interest (POIs) can be extracted from dielectric properties of the food product. However, for POIs showing a minor sensitivity in terms of dielectric response of the food product, it is challenging to extract them from reflection and transmission spectra. Therefore, there is a need for mm wave based sensors with enhanced sensitivity, which can be adjusted as desired. Methods: A dielectric permittivity sensitivity enhancement technique has been developed to enable the detection of very small changes of the POIs. Such sensitivity enhancer has effect of magnifying the small signal change due to the minute change in the dielectric properties of the sample under test. To demonstrate the concept, the moisture content of flat potato slices is monitored during the natural drying process and the food response to EM waves is measured both by a traditional mm-wave sensor and by another one implementing the proposed sensitivity enhancer. Results: Sensitivity of the sensor has been increased by 5 orders of magnitude compared to traditional mm-wave based sensors for the same amount of moisture content reduction (Fig.1). Enhancer featuring different sensitivity levels have been designed and tested. Conclusion: By accurate usage of the high sensitive mm-wave based sensors precise, real time and non-destructive characterization of POIs of food is possible. This sensor technique can make the optimization of food production processes effective.
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