The device relies on an electrochemical sensor that analyzes sweat to measure levels of the hormones cortisol, which is associated with alertness and stress response, and melatonin, which is responsible for sending sleep signals to the body.
Using the CORTI wearable platform developed by EnLiSense, this study is the first of its kind to track the circadian rhythm of cortisol and melatonin hormones through natural body sweat, without any external intervention. The company is currently working to commercialize the platform.
This innovation comes amid growing global interest in wearable devices for monitoring sleep and general health, as the sensor offers a new approach to measuring hormones continuously and without intrusive to users.
Annapurna Ramasubramania, a PhD student in biomedical engineering and the lead author of the study, said that accurate and continuous assessment of the hormones cortisol and melatonin is essential for understanding and managing circadian rhythm health, noting that traditional methods based on saliva samples are unsuitable for continuous monitoring.
Saliva samples are the standard for measuring these hormones, but their use in sleep studies requires frequently waking participants to collect samples, which can affect sleep quality and study results. The new device overcomes this problem by continuously measuring hormones through naturally occurring sweat.
During the study, 43 participants wore the sensor for 48 hours, and 12 saliva samples were collected from each participant for comparison. The results showed a high degree of consistency between the readings, confirming the sensor's accuracy and reliability.
Dr. Shalini Prasad, professor and chair of the Department of Bioengineering at the Eric Johnson College of Engineering and Computer Science, and co-author of the study, explained that the device represents an important addition to chronobiology, which studies natural biological rhythms.
She added that currently available wearable devices only estimate sleep based on movement, heart rate, and sometimes body temperature, while the CORTI device provides objective hormonal data that helps individuals understand their sleep patterns more accurately.
The study was published in the journal Biosensors and ioelectronics: X.
