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A water-soluble label for food products prevents packaging waste and counterfeiting


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.

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Fig. 1: Characterization of water-soluble nanocomposite ink.
Fig. 2: Design and optical characteristics of the metasurface-based structural colour.
Fig. 3: Mass production of metasurface-based label using wafer-scale NIL.
Fig. 4: Food label for anti-counterfeiting and humidity sensing.

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Data availability

The data that support the findings of this study are available from the corresponding authors upon reasonable request.


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This work was financially supported by the Samsung Research Funding & Incubation Center for Future Technology grant (SRFC-IT1901-52) funded by Samsung Electronics, the POSCO-POSTECH-RIST Convergence Research Center program funded by POSCO, the National Research Foundation (NRF) grants (NRF-2022M3C1A3081312, NRF-2022M3H4A1A02074314, NRF-2019R1A5A8080290, RS-2023-00283667, RS-2023-00302586) funded by the Ministry of Science and ICT of the Korean government, and the Korea Evaluation Institute of Industrial Technology grant (no. 1415179744/20019169, Alchemist project) funded by the Ministry of Trade, Industry and Energy of the Korean government. J.K. and H. Kim acknowledge the Asan Foundation Biomedical Science fellowships. J.K. and H. Kim acknowledge the POSTECH Alchemist fellowships. J.C., Y.C. and J.R. acknowledge the Catalyst: Strategic New Zealand–Republic of Korea Joint Research Partnerships programme (C11X2107) funded by the Ministry of Business, Innovation and Employment of the New Zealand government, and the NRF grant (NRF-2021K1A3A1A17086079) funded by the Ministry of Science and ICT of the Korean government. We thank T. Badloe (POSTECH) for English proofreading and fruitful discussion. We thank G. Jeon, K.-I. Lee and D. H. Yoon (RIST) for the technical support of nanoimprint lithography.

Author information

Authors and Affiliations



J.R. conceived the idea and initiated the project. J.K. and J.R. designed the experiments. H. Kim performed the theoretical and numerical simulations. J.K. fabricated the nanopatterns and devices. H. Kang and W.K. performed the nanoimprinting and replication of the devices. J.C. and Y.C. performed the nano-ink analysis. J.K., H. Kang and H. Kim performed the experimental characterizations and data analysis. J.K., H. Kim and H. Kang mainly wrote the manuscript. All authors confirmed the final manuscript. J.R., J.C. and H.L. guided the entire work.

Corresponding authors

Correspondence to Jonghyun Choi, Heon Lee or Junsuk Rho.

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Competing interests

The authors declare no competing interests.

Peer review

Peer review information

Nature Food thanks Cheng-Wei Qiu, Jia Zhu and Senentxu Lanceros-Méndez for their contribution to the peer review of this work.

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Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Extended data

Extended Data Fig. 1 Reflected colour at oblique viewing angles.

Calculated reflectance spectra (left side) and measured colours (right side) at the incident angle θi from 0° to 60° for the metasurface with (a) P = 305 nm, (b) P = 350 nm, and (c) P = 410 nm.

Extended Data Fig. 2 Preparation for QR code label.

(a) Photograph of a master stamp for a QR code fabricated by high-speed electron-beam lithography. (b) Photograph of a replica mould for the QR code fabricated by spin-coating and curing a h-PDMS/PDMS bilayer. (c) OM image of microprinting in the master stamp.

Extended Data Fig. 3 Effect to label under various light conditions.

Photograph of the printed QR codes under various lighting conditions. (a) Yellow light condition. (b) White light condition. (c,d) Natural light condition. The printed QR codes are recognized well regardless of light conditions, and they all reflect green colour with only slight variations in hue.

Extended Data Fig. 4 Reversible colour variation under different humidity.

OM images illustrating reversible colour variations under different humidity conditions from RH 55% to 80%. Brief exposure to high humidity (RH 75% and above) for around 20 seconds causes size adjustments in nanostructures, resulting in noticeable colour shifts. Once humidity exposure stops, the colour returns to its original state. These colour variations in the labels serve as a simple and effective humidity sensing mechanism.

Extended Data Fig. 5 Humidity stability test.

Humidity stability of the QR codes in a humidity-controlled chamber for 3 days. Even with long-term exposure to humidity conditions below RH 75%, the printed QR codes show no changes in colour or shape, ensuring reliable QR code recognition. This demonstrates the stability of the labels during product transportation.

Extended Data Fig. 6 Thermal stability test.

Thermal stability of the QR codes on a hotplate for 3 days. Below 70 degrees Celsius, the printed QR codes consistently reflect a green colour without shape deformations. This confirms the thermal stability of the labels in high-temperature environments.

Extended Data Fig. 7 Mechanical stability test.

Mechanical stability of the QR codes printed on a flexible PET film under bent condition: (a) tensile and (b) compressive bending. The QR codes printed on a flexible film endure both tensile and compressive bending with the 3 cm curvature radius. This demonstrates the high stability of labels under bending stress, showing their applicability for curved packaging.

Supplementary information

Supplementary Information

Supplementary Notes 1–8.

Reporting Summary

Supplementary Video 1

Water-solubility test of the fabricated full-colour label.

Supplementary Video 2

Scanning fabricated QR code for product information.

Supplementary Video 3

Humidity sensing with red pixel colour variation.

Supplementary Video 4

Reversible colour changes based on various humidity levels.

Supplementary Video 5

Scanning QR code after humidity and thermal stability test.

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Kim, J., Kim, H., Kang, H. et al. A water-soluble label for food products prevents packaging waste and counterfeiting. Nat Food 5, 293–300 (2024).

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