Researchers at the University of California San Diego have designed a wearable sensor which tracks a person's vitamin C levels by analyzing their sweat — and is looking to expand the technology to track other vitamins, too.
"Wearable sensors have traditionally been focused on their use in tracking physical activity, or for monitoring disease pathologies, like in diabetes," says first author Juliane Sempionatto of her team's work. "This is the first demonstration of using an enzyme-based approach to track changes in the level of a necessary vitamin, and opens a new frontier in the wearable device arena.
"Ultimately, this sort of device would be valuable for supporting behavioural changes around diet and nutrition. A user could track not just vitamin C, but other nutrients — a multivitamin patch, if you will. This is a field that will keep growing fast."
The team targeted vitamin C — ascorbic acid — owing to the body's inability to produce it naturally and its importance for supporting the immune system, collagen production, and the absorption of iron. There was another key reason for its focus as well: Several ongoing trials targeting vitamin C as a potential agent to assist in the recovery from COVID-19 and other diseases causing acute respiratory distress syndrome (ARDS).
The compact wearable takes the form of a flexible circuit on an adhesive patch, designed to stimulate sweating and detect the levels of vitamin C — the latter by putting ascorbate oxidase, an enzyme which generates a current when encountering vitamin C, into the electrodes of the device. In testing with four human subjects, the sensor was able to track vitamin C level changes caused by supplements and fruit juices over a period of two hours.
"Despite the rapid development of wearable biosensors, the potential of these devices to guide personalized nutrition has not yet been reported," says lab lead Joseph Wang. "I hope that the new epidermal patch will facilitate the use of wearable sensors for non-invasive nutrition status assessments and tracking of nutrient uptake toward detecting and correcting nutritional deficiencies, assessing adherence to vitamin intake, and supporting dietary behaviour change."
The team's work has been published under closed-access terms in the journal ACS Sensors.