Sustainability, humidity sensing and product origin are important features of food packaging. While waste generated from labelling and packaging causes environmental destruction, humidity can result in food spoilage during delivery and counterfeit-prone labelling undermines consumer trust. Here we introduce a food label based on a water-soluble nanocomposite ink with a high refractive index that addresses these issues. By patterning the nanocomposite ink using nanoimprint lithography, the resultant metasurface shows bright and vivid structural colours. This method makes it possible to quickly and inexpensively create patterns on large surfaces. A QR code is also developed that can provide up-to-date information on food products. Microprinting hidden in the QR code protects against counterfeiting, cannot be physically detached or replicated and may be used as a humidity indicator. Our proposed food label can reduce waste while ensuring customers receive accurate product information.

可持续性、湿度传感和产品来源是食品包装的重要特征。虽然标签和包装产生的废物会造成环境破坏，但湿度会导致食品在运输过程中变质，而容易出现假冒标签会损害消费者的信任。在这里，我们介绍一种基于具有高折射率的水溶性纳米复合材料墨水的食品标签，可以解决这些问题。通过使用纳米压印光刻对纳米复合材料墨水进行图案化，所得的超表面显示出明亮且生动的结构颜色。这种方法可以在大表面上快速且廉价地创建图案。还开发了二维码，可以提供有关食品的最新信息。隐藏在二维码中的缩微印刷可以防止伪造，无法物理分离或复制，并且可以用作湿度指示器。我们提出的食品标签可以减少浪费，同时确保客户收到准确的产品信息。