Sensorized Nozzle for Material Properties Monitoring through Electromagnetic Field

This paper proposes the use of a circular waveguide operating around the fundamental mode cut-off frequency to be employed as a sensorized nozzle in the food industry or in 3D printers. Specifically, this paper aims to demonstrate the use of a metallic nozzle as a circular waveguide to detect foreign bodies or air bubbles during material sliding in order to guarantee an automatic product quality assessment. As a matter of fact, the presence of undesired inclusions changes the mixture dielectric permittivity, resulting in the waveguide cut-off frequency shift. To validate this theoretical approach, a circular waveguide operating around 2.5 GHz has been numerically designed and a set of materials, different in terms of dielectric properties, are used as waveguide fillers. A correlation between the real part of the material permittivity and the cut-off frequency shift has been observed, hence proving the possibility to detect foreign bodies or air by using the metallic nozzle as a circular waveguide. Therefore, the proposed system can be potentially used for innovative industrial applications, encouraging further analysis.