Scientists unveil cyberphysical watermarks to protect meds

Researchers at Purdue University in the US have developed an on-dose authentication system for medicines that is a variant of a technology used to place photos on foods like cakes.

The technology developed by a team led by Young Kim, associate head for research and an associate professor in Purdue's Weldon School of Biomedical Engineering, is based on a cyberphysical watermark.

The watermark is printed on specialised fluorescent silk with FDA-approved food dye using an inkjet process, and adhered to an oral dosage form like a tablet using a simple sugar-based glue. As a natural protein silk is safe to ingest, according to the researchers.

"We are affixing a watermark on an individual medicine that is readable by a smartphone camera to extract a hidden digital key," said Kim.

That allows patients "to check to see if the cyberphysical watermark on the medications they are taking is real or counterfeit…and to also confirm dose, frequency and information on the medicine," he added.

Using the approach the scientists have been able to make a watermark of around 5mm across – small enough for many tablets – and the team has refined the technology to make sure it will work  under different light conditions and with different cameras.

"The reference colours on the watermark’s periphery allow us to know the true colour value of the watermarked image as each smartphone has different spectral sensitivity," according to Kim. Now, the aim is to adapt the technology to work with liquid medicines.

The research is published in the journal Advanced Functional Materials.

Kim et al see the approach as complementary to the coding enshrined within the US Drug Supply Chain Security Act (DSCSA), due to come fully into force in 2023, which allows for pack-level traceability.

The scientists acknowledge however that adding traceability directly on a pill could require adding numerous manufacturing and data management steps.

Along with the anti-counterfeit applications, the on-dose printing method could also facilitate the use of single-unit packages or unit-dose packages in hospital pharmacy settings that could "lower the risk of dispensing errors, improve inventory tracking, enhance security, and minimise labour costs," they write in the journal article.