Invisible Optical Tags Printed on Textiles

Product-related digital data attached directly to the product, its packaging, or a separate label has been used for decades. The 1-dimensional (1D) barcode is the most typical example of such technology, known for its remarkably low cost. While the traditional 1D barcode typically provides very brief information, such as the price of a product, 2-dimensional optical codes, such as QR codes, or more complex solutions like NFC tags, can convey much more information. This is especially true when they provide a pointer to data located on the internet. This data can include various types of information, such as instruction manuals, recycling instructions, brand advertising, or data required by the Digital Product Passport (DPP) currently being specified by the European Union. This paper discusses embedding optical tags directly into textiles. Particularly for clothing, such tags should be invisible to the human eye to avoid ruining the visual appearance. A clear benefit of this approach is that it keeps the related data available for the entire lifetime of the textile product. In contrast, conventional separate labels are likely to get lost, even on the first day after being purchased by a consumer. Low-cost implementation would also allow printing such a tag on the fabric multiple times, making it easier to find the tag, which benefits both customers and automated recycling processes. This paper describes several options for implementing mainly 2-dimensional tags printed on fabric and discusses their benefits and drawbacks. The goal of the work was to find solutions for both professional and consumer applications.