A Microwave Imaging Device for Detecting Contaminants in Water-based Food Products

Food and beverage industries are paying an increasing attention to the development of new technologies for non-invasive assessment of food products. In particular, there is a need of deploying tools to detect low-density plastic, rubber, wood and glass that are unlikely to be detected by X-Rays, currently used in the most powerful commercial systems. To this end, we propose a microwave-based device, exploiting the dielectric contrast between potential intrusions (e.g., plastic fragments) and the surrounding medium, represented by the food/beverage product. In particular, this work aims to numerically assess this principle of detection to water-based products that are, due to the medium losses, a challenging category at microwaves. An antennas array surrounds the object moving along the production line, to monitor the electromagnetic signal variations with respect to a reference case. The working frequency is chosen by selecting a proper trade-off between penetration depth and image resolution. Then, a procedure, based on the application of the distorted-Born approximation is applied to reconstruct a 3-D image of the contaminant position. Finally, the successful detection of a millimetric-sized plastic sphere is presented in the case of a common commercial bottle filled with water.