Karmakar Subhajit, Kludze Atsutse, Chandra Ranveer, Ghasempour Yasaman
Department of Electrical and Computer Engineering, Princeton University, Princeton, NJ, USA.
Microsoft Research, Redmond, WA, USA.
Nat Food. 2025 Jan;6(1):97-104. doi: 10.1038/s43016-024-01083-x. Epub 2025 Jan 2.
Fruits and vegetables account for around a third of all food loss and waste. Post-harvest, retail and consumer losses and waste could be reduced with better ripeness assessment methods. Here we develop a sub-terahertz metamaterial sticker (called Meta-Sticker) that can be attached to a fruit to provide insights into the edible mesocarp's ripeness without cutting into the produce. The fruit acts as a complex multilayer substrate to Meta-Sticker and, when excited by sub-terahertz signals, generates two distinct resonances: localized dipole resonance that correlates with the exocarp's refractive index; and propagating plasmon resonance that penetrates into the mesocarp and resembles the rare phenomenon of 'extraordinary transmission'. The Meta-Sticker accurately predicted the ripeness of different fruits with a cumulative normalized root mean square error of 0.54% of the produce tested. This study offers a non-invasive, low-cost and biodegradable solution for accurate ripeness assessment with applications in distribution optimization and food waste reduction.
水果和蔬菜约占所有食物损失和浪费的三分之一。通过更好的成熟度评估方法，可以减少收获后、零售和消费者层面的损失与浪费。在此，我们开发了一种亚太赫兹超材料贴纸（称为“元贴纸”），它可以贴在水果上，无需切开水果就能深入了解可食用中果皮的成熟度。水果对元贴纸而言就像一个复杂的多层基板，当受到亚太赫兹信号激发时，会产生两种不同的共振：与外果皮折射率相关的局域偶极子共振；以及穿透到中果皮且类似于“超常透射”这一罕见现象的传播表面等离子体共振。元贴纸能够准确预测不同水果的成熟度，在测试的农产品中，累积归一化均方根误差为0.54%。这项研究为准确的成熟度评估提供了一种非侵入性、低成本且可生物降解的解决方案，可应用于配送优化和减少食物浪费。
