3 Minutes
A portable breakthrough in stress-hormone measurement
A newly developed biosensor built from computationally designed proteins can detect cortisol—the body’s primary stress hormone—with laboratory-grade sensitivity and translate that signal into a visible light readout that a smartphone camera can capture. Cortisol regulates blood pressure, metabolism and immune responses, and abnormal cortisol levels are linked to conditions ranging from adrenal disorders to chronic stress and depression. Making accurate cortisol measurement more accessible could improve diagnosis and monitoring of these conditions.
A groundbreaking biosensor powered by protein design and smartphone cameras could transform how we measure the body’s stress hormone, cortisol, bringing lab-level precision to point-of-care testing. Credit: Shutterstock
How the sensor works: engineered proteins and luminescent reporting
This sensor was created using AI-guided computational protein design to build novel proteins from scratch rather than repurposing natural ones. In the presence of cortisol in a small volume of blood or urine, two engineered protein components are drawn together. Their proximity triggers a luminescent signal: the brighter the emission, the higher the cortisol concentration. A peer-reviewed study in the Journal of the American Chemical Society validated the sensor across the full physiological range relevant to human health.
UC Santa Cruz Assistant Professor of Biomolecular Engineering Andy Yeh’s lab focuses on artificial protein design. Credit: Impact Creative for UC Santa Cruz
Andy Yeh, assistant professor of biomolecular engineering at UC Santa Cruz, demonstrated that a standard smartphone camera plus a simple app can quantify the light output and convert it to a hormone concentration. Because the readout is optical, the approach eliminates dependence on costly lab instruments while preserving high sensitivity and a wide dynamic range—able to report low, normal and elevated cortisol values quantitatively.
Point-of-care use, advantages and future prospects
The envisioned test is 'mix-and-read'—similar in user flow to many rapid antigen tests. A drop of blood or urine is mixed with the biosensor solution, allowed to react, and photographed with a phone. Software interprets light intensity and color to produce a cortisol value suitable for clinical or at-home monitoring. This low-cost, portable diagnostic could support chronic disease management, studies of stress physiology, and drug development where precise, frequent hormone measurements are needed.
Yeh notes that 'the output of the sensor is light emissions, so essentially you can just take a picture of the test with your smartphone,' underscoring the field compatibility of the design. The team intends to refine device integration, matrix robustness and regulatory pathways to move toward clinical deployment.
Conclusion
Computational protein design combined with smartphone imaging offers a practical route to democratize cortisol testing. By providing quantitative, lab-comparable results at the point of care, this biosensor could transform how clinicians and individuals monitor stress-related health and accelerate research into disorders tied to cortisol imbalance.
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