Researchers at the University of California, Irvine have developed a wearable bioelectronic wristband that can monitor stress continuously, objectively and in real time. The device, called the Smart Quantitative and Comprehensive Stress Assessor and Sub-Classifier (SQC-SAS), combines measurements of molecular stress biomarkers with physiological signals to provide a detailed and dynamic picture of how stress manifests itself in humans.
Stress plays a major role in both mental and physical health problems, but reliable measurement remains difficult. Many existing methods are subjective, such as self-reports, or provide only snapshots that do not provide insight into changes over time. The new wristband aims to overcome this by simultaneously measuring and analysing multiple biosignals using machine learning.
‘Stress is not a single signal, but a dynamic physiological and biochemical response,’ says Rahim Esfandyar-pour, associate professor at UC Irvine. ‘By measuring molecular biomarkers and physiological signals simultaneously, we reduce uncertainty and obtain a more specific and informative picture of stress.’
Multimodal biosensing
Unlike many wearables that rely on a single indicator, SQC-SAS combines multiple synchronised measurements. The system consists of a physiological patch that records heart rate and skin conductance, among other things, coupled with a molecular patch that detects cortisol in sweat. The data is collected wirelessly and analysed by an AI model that recognises and classifies stress patterns.
According to the research team, existing approaches often fall short. Cortisol measurements are usually invasive and require specialised personnel, while purely physiological measurements are sensitive to confounding factors such as physical activity, nutrition, environment or day-night rhythm. ‘With ECGs or skin conductance alone, you quickly get false positive or false negative results,’ says Esfandyar-pour. ‘Our wireless, battery-free and automated wearable measures both physiological and molecular signals, providing a much more accurate stress profile.’ The video below demonstrates the bioelectrical poslband.
Application for a growing health problem
The wristband, described in Nature Communications, is designed to be as user-friendly and non-invasive as possible, so that wearers hardly notice it while their stress levels are continuously recorded. In doing so, SQC-SAS is responding to a growing health problem.
Recent figures show that more than half of Americans and 60 per cent of people in 34 countries experienced stress that was difficult to manage in the past year. Chronic stress increases the risk of conditions such as anxiety disorders, depression, cardiovascular disease and obesity. With SQC-SAS, the researchers want to contribute to earlier and more objective detection of stress, as a basis for prevention and more targeted interventions in healthcare.
Measuring stress with a saliva test
Most wearables such as fitness bands and smartwatches now also have a so-called stress indicator measurement. Another development that came to light last year is the measurement of stress using a saliva test. This technology, developed by researchers at the University of Cincinnati, uses a compact, portable device in which a patient can easily place a saliva sample. Within minutes, the data is sent via a reader to a smartphone or other mobile device.
This reduces diagnostics that normally take days to just a few minutes, is completely non-invasive and suitable for home use. This innovative point-of-care test provides healthcare professionals with objective data to identify stress-related conditions such as depression and anxiety at an early stage.
