Summary: A new wearable sensor can continuously measure cortisol levels in a person’s sweat.
Source: EPFL
Stress is a universal experience, but until now clinicians and researchers have had limited tools to quantify it objectively. Engineers at EPFL’s Nanoelectronic Devices Laboratory (Nanolab), in collaboration with Xsensio, have developed a wearable sensor that measures cortisol—the primary stress hormone—directly from sweat, continuously and in real time.
Cortisol: a vital but volatile hormone
Cortisol is a steroid hormone produced by the adrenal glands from cholesterol and regulated by adrenocorticotropic hormone (ACTH) from the pituitary. It plays essential roles in metabolism, blood sugar control, blood pressure regulation, immune response and cardiovascular function. When we face stressful or demanding situations, cortisol mobilizes energy to the brain, muscles and heart.
Cortisol follows a daily circadian rhythm, typically peaking in the early morning and declining through the day. Disruption of this rhythm, or chronically elevated or depleted cortisol levels, is linked to serious health conditions including obesity, cardiovascular disease, depression and burnout. Measuring cortisol patterns over time could help diagnose and manage these conditions more effectively.
Measuring cortisol in sweat with a wearable patch
Traditional cortisol testing relies on blood, urine or saliva samples taken at discrete time points. The EPFL/Xsensio team chose sweat as a practical, non-invasive fluid for continuous monitoring and designed a compact wearable patch that integrates a miniaturized sensor.
The sensor combines a transistor with a graphene-based electrode. Graphene’s electrical properties provide high sensitivity and low detection limits. The electrode surface is functionalized with aptamers—short single-stranded DNA or RNA fragments engineered to bind specifically to cortisol. These aptamers carry a negative charge; when cortisol binds, the aptamer folds and brings charge closer to the electrode surface. The transistor detects these charge changes and converts them into a quantitative cortisol reading.
Unlike existing approaches, this wearable patch enables continuous monitoring of cortisol across the full circadian cycle. That continuous, quantitative readout is the key advance: scientists and clinicians can obtain objective, time-resolved profiles of stress hormone dynamics in a non-invasive way, across the physiological range found in human sweat.
Testing, clinical integration and potential impact
The sensor was tested on Xsensio’s Lab-on-Skin™ platform. The next stage focuses on clinical trials: EPFL and Xsensio have initiated a bridge project with Prof. Nelly Pitteloud, chief of endocrinology, diabetes and metabolism at Lausanne University Hospital (CHUV), to evaluate the system in human subjects. Trials will include healthy participants and patients with disorders of cortisol regulation such as Cushing’s syndrome (excess cortisol), Addison’s disease (insufficient cortisol) and stress-related obesity.
A reliable wearable cortisol monitor would also transform how psychological conditions linked to stress are assessed. Currently, diagnoses of depression, burnout and related disorders rely heavily on subjective reports of mental state. Continuous, objective cortisol measurements could help clinicians determine physiological dysfunction, track treatment responses in real time and better understand the relationship between hormone rhythms and mental health.
Xsensio’s CEO Esmeralda Megally highlights the collaborative milestone in cortisol detection and the intent to bring the sensor into hospital testing and commercial Lab-on-Skin sensing platforms. Future development aims to integrate the technology into next-generation wearables, potentially enabling stress monitoring through smart bracelets and other consumer or clinical devices.
About this research and next steps
Source: EPFL
Contact: Julie Haffner – EPFL
Image: The image is in the public domain
Original Research: Extended gate field-effect-transistor for sensing cortisol stress hormone, published open access in Communications Materials by Shokoofeh Sheibani, Luca Capua, Sadegh Kamaei, Sayedeh Shirin Afyouni Akbari, Junrui Zhang, Hoel Guerin and Adrian M. Ionescu.
Abstract (concise overview)
This work presents a wearable electronic sensor that uses a platinum/graphene aptamer extended-gate field-effect transistor (EG-FET) for label-free recognition of cortisol in biological fluids within the Debye screening length. The device demonstrates features suitable for real-time monitoring of cortisol’s circadian rhythm in human sweat, including a 0.2 nM detection limit across a wide physiological range (1 nM to 10 µM), voltage sensitivity around 14 mV/decade, current sensitivity up to 80% over four concentration decades, negligible drift and high selectivity. The dynamic range covers expected human sweat concentrations, and the authors provide an analytical mapping of current sensitivity across operating regimes.