AgriTera: Accurate Non-Invasive Fruit Ripeness Sensing via Sub-Terahertz Wireless Signals

Abstract

The potential to transform the agriculture sector and reduce food waste significantly lies in the ability to assess the quality of fruits and vegetables on a large scale. This article introduces AgriTera, an innovative solution that utilizes sub-terahertz wireless signals for accurate and non-invasive fruit ripeness sensing, without the need for physical contact. The underlying idea is that sugar and water concentrations in fruits, linked to ripening, create distinctive patterns in the wideband spectrum of reflected signals from the fruit body. AgriTera leverages the sub-THz bands due to their wide bandwidth, sensitivity to water, millimeter-scale penetration depth, and non-ionizing features. This enables high-resolution inferences from both the peel and pulp underneath. A chemometric model is developed to translate reflection spectra into well-known ripeness metrics like Dry Matter and Brix. Extensive over-the-air experiments using commercial sub-THz transceivers are conducted and compared with ground truth values from specialized sensors and a vision-based scheme.