Researchers create invisible QR codes to stop fakes

US researchers have created invisible QR codes to combat counterfeiting of money and other items.

The Quick Response (QR) codes are invisible until viewed under a near-infrared light. Despite this a smartphone can still scan the covert anti-counterfeiting technology to confirm the product is authentic.

“We suggest these covert QR codes could be used economically and efficiently in security printing. The inks are produced from inexpensive starting materials, and very small amounts of ink are required to produce readable images,” researchers wrote in the journal Nanotechnology.

Invisible QR codes are applied using aerosol jet printing and - the researchers say - are suitable for use on most solid objects. The codes carry up to 100 times more information than barcodes and this complexity makes them potentially a more effective anti-counterfeiting technology.

Embedding of letters or symbols into the QR codes provides an added layer of security. The extra elements are printed using different coloured inks and can range from the macroscopic and microscopic in size.