Researchers at UBC and the Paul Scherrer Institut (PSI) in Switzerland have created a microneedle drug-monitoring system that could one day replace blood draws and improve patient comfort. The system consists of a small thin patch that is pressed against a patient’s arm during medical treatment and measures drugs in the bloodstream painlessly without drawing any blood. The tiny needle-like projection, less than 0.5 mm long, resembles a hollow cone and doesn’t pierce the skin like a standard hypodermic needle.

Researcher Sahan Ranamukhaarachchi, a PhD student and Vanier scholar in UBC’s Faculties of Applied Science and Pharmaceutical Sciences, developed this technology during a research exchange at PSI. Microneedles are designed to puncture the outer layer of skin, but not the next layers of epidermis and the dermis, which house nerves, blood vessels, and active immune cells.

The microneedle created by Mr Ranamukhaarachchi and his colleagues was developed to monitor the antibiotic vancomycin, which is used to treat serious infections and is administered through an intravenous line. Patients taking the antibiotic undergo three to four blood draws per day and need to be closely monitored because vancomycin can cause life-threatening toxic side effects. Researchers discovered that they could use the fluid found just below the outer layer of skin, instead of blood, to monitor levels of vancomycin in the bloodstream. The microneedle collects less than a millionth of a millilitre of fluid, and a reaction occurs on the inside of the microneedle that researchers can detect using an optical sensor. This technique allows researchers to quickly determine the concentration of vancomycin.

The microneedle monitoring system is described in a paper published in the July 2016 issue of Scientific Reports, “Integrated hollow microneedle-optofluidic biosensor for therapeutic drug monitoring in sub-nanoliter volumes.”