Engineers and neuroscientists at the University of California San Diego have developed a soft, wearable fingertip patch that continuously tracks a patient’s Parkinson’s disease medication levels through their sweat. The device operates using chemicals in the patient’s sweat and requires no batteries. Its measurements were comparable to those obtained by standard laboratory blood tests, according to research published in Proceedings of the National Academy of Sciences.
The patch monitors levodopa, the gold-standard drug for managing the loss of motor control caused by Parkinson’s disease. Prescribing the right dose is challenging, since reducing levodopa leaves patients unable to move while too much triggers severe, uncontrollable jerking movements. As the disease progresses, the therapeutic window can narrow to as little as two hours, and clinicians currently rely on subjective patient diaries that often fail to catch dangerous dosing gaps.
The patch is worn on the fingertip, an area packed with a high density of sweat glands, and is equipped with an absorbent gel that acts like a sweat sponge, drawing sweat out of the pores through a concentrated mixture of salts and benign solvents. When levodopa in the patient’s sweat contacts enzymes embedded in the patch, it triggers a chemical reaction that generates a small, measurable voltage, which both powers the device and indicates levodopa levels.
The project was led by study co-first author Tamoghna Saha, a postdoctoral researcher in the lab of Joseph Wang, professor in the Aiiso Yufeng Li Family Department of Chemical and Nano Engineering at the UC San Diego Jacobs School of Engineering. The engineering team developed the technology in collaboration with the lab of Irene Litvan, professor in the Department of Neurosciences at UC San Diego School of Medicine.
In clinical tests involving healthy volunteers and patients with Parkinson’s, the patch tracked levodopa levels as accurately as standard laboratory blood tests, which take days to return results. The data revealed that individuals with Parkinson’s clear levodopa from their systems significantly faster than healthy individuals, a finding that may explain why a patient’s symptoms can deteriorate suddenly. The technology lays the groundwork for a closed-loop system in which a monitoring patch could communicate with a pump to automatically deliver precise doses of the drug. The team is also developing microneedle-based wearable systems to monitor levodopa continuously, described in a separate paper published in ACS Sensors.
