# Engraved Microwave Metasurfaces for Potential Application in Honey Quality Control

## TL;DR

This study explores engraved microwave metasurfaces as sensors for detecting honey quality and adulteration.

## Contribution

The novelty lies in using engraved metasurfaces for honey quality control, showing distinct electromagnetic responses to different honey types and adulterants.

## Key findings

- Metasurfaces showed resonance frequency shifts when exposed to different honey types.
- They detected adulterants like sugar and microplastics through frequency and intensity changes.
- Their performance matched spectroscopic techniques like Raman and FTIR.

## Abstract

In this study, millimeter-scale
metasurfaces are examined concerning
their capability as potential honey quality control sensors. In particular,
complementary split-ring resonator metasurfaces were developed through
the Computer Numerical Control engraving method. Under unloaded conditions,
the metasurfaces exhibited fundamental resonance frequencies in the
range of 3–6 GHz, depending on their size as well as the measurement
orientation. Moreover, their electromagnetic response was studied
in the presence of different honey types, such as chestnut, pine,
and orange blossom honey. A corresponding resonance frequency shift
was observed, suggesting the distinct electromagnetic response of
the fabricated structures with respect to the honey type. Furthermore,
the hereby studied resonators were tested against various types of
honey adulteration, such as sweeteners (sugar and maple syrup), as
well as microplastic contamination. The metasurfaces exhibit a discrete
resonance frequency shift along with modulation of the resonance intensity
in honey adulteration, enabling them to act as efficient honey quality
detectors. In addition, their electromagnetic performance was compared
to other state-of-the-art spectroscopic techniques dedicated to honey
contamination, in particular, Raman and FTIR. It was found that spectroscopic
evidence is consistent with the metasurface electromagnetic response,
giving credence to their performance. All in all, it is evident that
the hereby studied metasurfaces exhibit significant performance in
honey adulteration sensing, allowing their potential application as
sensors for honey quality control.