Author perspective
“For decades, measuring hormones like cortisol required invasive sampling or isolated laboratory tests. Our goal with this study was to demonstrate that wearable biochemical sensing can capture these signals continuously and non-invasively. By translating lateral-flow diagnostic principles into wearable formats, we can monitor dynamic physiology in the real world, not just in the lab.”
Roozbeh Ghaffari, PhD — CEO and co-founder, Epicore Biosystems
Study findings
Understanding how the body responds to stress in real time has long been a challenge for researchers and clinicians alike. Cortisol, often called the stress hormone, plays a central role in regulating metabolism, circadian rhythms, immune function, and the body’s response to both physical and psychological stress.
This study presents a wearable lateral-flow platform that measures cortisol in human sweat, making it possible to monitor hormonal changes as they happen through the day. The device pairs paper-based microfluidics with colorimetric assays in a lateral flow configuration, so cortisol is measured directly from sweat as it is produced on the skin.
By capturing time-resolved cortisol dynamics, this approach lets researchers observe fluctuations tied to circadian rhythms, physical activity, stress responses, and disruptions such as jet lag. It moves wearable biochemical sensing past static laboratory testing and toward continuous monitoring in real-world environments.
Scientific highlights
Continuous cortisol monitoring in sweat
The wearable lateral-flow platform enables non-invasive, real-time detection of cortisol concentrations directly from sweat.
Time-dynamic hormone tracking
The system captures temporal fluctuations in cortisol associated with circadian cycles, stress responses, and behavioral patterns.
Paper microfluidics meets wearables
Demonstrates how low-cost lateral flow diagnostics can be successfully integrated into skin-mounted wearable platforms.
Real-world health monitoring
Continuous hormone tracking opens new opportunities for monitoring stress physiology, fatigue, and recovery outside of clinical settings.
Why this research matters
Traditional biomarker testing relies on blood draws or intermittent laboratory measurements, isolated snapshots that miss the dynamic nature of hormonal physiology. Wearable sweat sensing offers a fundamentally different approach: because sweat contains a rich set of biochemical markers, it can serve as a continuous, non-invasive window into human physiology.
This research demonstrates how wearable biosensors combined with lateral-flow diagnostics can transform hormone monitoring from an episodic clinical test into a continuous, everyday capability.
Applications:
- Athletic performance & recovery
- Worker safety & fatigue
- Mental health & stress research
- Circadian rhythm & sleep studies
How this connects to Epicore’s solutions
Epicore’s mission is to translate biochemical signals from the body into actionable insights that improve human health, safety, and performance. Our wearable sweat sensing platforms already measure hydration, electrolyte balance, and physiological strain in athletes, workers, and military personnel.
This work, a collaboration with researchers at Northwestern University, expands the frontier of wearable diagnostics by showing how hormone monitoring through sweat can be integrated into these same systems. While our current platforms focus on hydration and electrolyte biomarkers, this research points to the future potential of multi-analyte sweat sensing, where additional biomarkers such as cortisol can provide deeper insight into stress, fatigue, and recovery.
Connected Hydration
Real-time sweat and hydration sensing for industrial workers, with personalized intervention before heat stress sets in.
GX Sweat Patch
A wearable microfluidic patch that gives athletes sweat rate and electrolyte feedback to tailor a personalized action plan.
Discovery Patch
An FDA-registered collection system for multi-biomarker sweat analysis in clinical studies, the foundation for cortisol work.
FAQs
Cortisol is a steroid hormone made by the adrenal glands, which sit on top of the kidneys. It gets called the stress hormone, but it does much more than that. Cortisol helps regulate blood sugar and metabolism, blood pressure, immune response, and the sleep-wake cycle. Its release is controlled by the hypothalamic-pituitary-adrenal axis, usually shortened to the HPA axis.
Cortisol follows a circadian rhythm. It sits at its lowest around midnight, climbs through the early morning, and peaks roughly 30 to 45 minutes after waking, a pattern known as the cortisol awakening response. It then falls through the rest of the day. Stress, exercise, illness, and disrupted sleep all shift it. This is why a single measurement is hard to interpret on its own: the same number can mean very different things at 7am and 7pm.
There are four common methods: a blood draw (serum cortisol), a saliva sample, a 24-hour urine collection, and hair analysis for longer-term exposure. All of them are episodic. You get a snapshot from the moment of sampling, or an average across a long window. What you don’t get is the shape of the curve between those points.
Yes. Cortisol is present in eccrine sweat, the type produced across most of the body. It appears at low concentrations, which is the hard part of the engineering problem. In this study, sweat cortisol tracked saliva cortisol with a correlation of 0.73 in human trials.
It’s the same technology behind a home pregnancy test or a rapid COVID test. A liquid sample wicks along a paper strip and passes a line of immobilized antibodies, and a color change at that line tells you what’s present. For small molecules like cortisol the strip runs as a competitive assay, so a higher cortisol concentration produces a fainter line rather than a stronger one.
Gold nanoflowers are gold nanoparticles grown with branched, petal-like surfaces instead of a smooth sphere. This branching adds surface area, so more antibody attaches and the color signal becomes stronger. That extra sensitivity is what makes it practical to read a low-concentration hormone off a paper strip by eye.
It samples in sequence. The platform uses electronic timers, or passive valves gated by a protein layer that dissolves at a set rate, to route sweat into separate assays at different moments. One patch produces several time-stamped readings across hours, which is what makes a trend visible rather than a single point.
It can measure a biological signal associated with the stress response, which isn’t quite the same thing. Cortisol rises with both physical and psychological stressors, and this study tracked it through normal circadian cycling, an acute cold pressor challenge, and circadian disruption caused by intercontinental travel. Stress involves far more than one hormone, though, and this is a research platform rather than a diagnostic tool.
Not today. This is published research, not a commercial product. Epicore’s current wearables measure hydration and electrolytes rather than hormones.
