Scientists develop under-skin sensor that shows bloodstream drug levels

The sensor functions based on colour-changing gold nanoparticles, which reflect infrared light when an infrared reader is used

Spotted: A new subdermal “tattoo” could help determine how much of a drug is actually making its way into a patient’s bloodstream when they receive medication. 

The transparent bio tissue-like device, which is not much bigger than a penny and thinner than one millimetre, is currently being developed by scientists at Germany’s Johannes Gutenberg University Mainz.

The sensor is made up of a biocompatible porous hydrogel, inside of which are gold nanoparticles that have been coated with receptors that respond to specific drug molecules.

After the sensor has been surgically implanted under the skin, blood vessels grow into it through its pores, carrying blood to the nanoparticles. Any of the targeted medication which is present in that blood will then bind with the receptors, causing the gold to reflect infrared light in a given colour. The colour reflected varies in a predictable manner, according to the concentration of the drug within the bloodstream. 

Although the nanoparticles can’t be seen with the naked eye, they show up through the skin when a special infrared reader is used. 

It has already been tested on hairless lab rats, accurately indicating the varying levels of an antibiotic in their bloodstreams. 

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