Project Millimeter wave sensors

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In the frame work of the Intelligence For Food project the millimeter wave sensors developed by the research group ETRO  of the Vrije Universiteit Brussel are identified as promising innovative sensor systems for the optimization of industrial drying and freezing processes in the food industry. These sensors allow for contact less measurements into the core of the food product. They combine the penetration depth hand the high resolution of millimeter waves. These waves have a very specific interaction with water. They are absorbed by free water molecules and the degree of absorption depends on the residual moisture in the food product.

As such, these sensors can be applies to measure the moisture content of for instance fresh vegetables and fruit of from dried nuts and fruits. With specific sensor configurations the drying temperature and drying speed can be monitored and the final moisture content determined. In contrast, upon freezing the millimeter waves are no longer absorbed, which makes these sensors suitable for monitoring freezing processes. Furthermore, millimeter waves do not suffer from dust, dirt, fog, or temperature effects which makes this system suitable for use on the production floor. A unique quasi-optical millimeter wave network analyzer is available that will be used in the project for demonstrations and experimental studies to determine which frequency bands are most suitable for the different applications. In a next step, prototypes will be developed that can reach the optimal sensitivity  and accuracy that will be tested on practical industrial drying and freezing applications. These compact sensor configurations can be installed above a production line and used for on-line monitoring of freezing and drying processes. The validation project combines technical evaluations (sensitivity, detection limit, robustness, measuring rate,…) with a comparative study of other measuring techniques and known destructive sampling experiments that will be used as references. After this validation, advice will be offered on the implementation of affordable integrated sensor solutions. Engineering companies that can build these more integrated versions are available.


More information on the technology: STW artikels  ‘Contactloos vochtpercentage meten bij industriële droogprocessen’ en ‘Contactloze temperatuursmeting bij industriële vriesprocessen (zie 

Partners: ETRO-Vrije Universiteit Brussel en INTEC (Universiteit Gent)

Why participate?: Feasibility tests for the determination of moisture content of you raw materials, intermediate products and end products and for the evaluation of freezing and drying processes are possible, followed by further optimization and suggestion of an integrated sensor solution based on your needs, taking into account the balance of cost versus measuring precision. After validation, in depth advice on implementation is offered.

How to participate? You have to be or become member of Flanders’ FOOD and contribute  (together with the other participating companies) 20% of the project budget. The validation project is also open for SME’s.

More information on this validation project, the work plan and the financial contribution can be found here