Over the past few decades, electronics engineers have developed increasingly sophisticated sensors that can reliably measure a wide range of physiological signals, including heart rate, blood pressure, respiration rate and oxygen saturation. These sensors were used to create both biomedical and consumer-facing wearable devices, advancing research and the real-time monitoring of health-related metrics, such as sleep quality and physiological stress.
Fatigue, a mental state marked by a decline in performance due to stress, lack of sleep, excessive activity or other factors, has proved to be more difficult to reliably quantify. Most existing methods for measuring fatigue rely on surveys that ask people to report how tired they feel, a method to record the brain’s electrical activity known as electroencephalography (EEG) or camera-based systems.
Most of these approaches are unreliable or only applicable in laboratory settings, as they rely on subjective evaluations, bulky equipment or controlled environments. These limitations prevent their large-scale deployment in everyday settings.
Researchers at University of California Los Angeles (UCLA) recently developed a new type of soft sensor that can reliably measure people’s levels of fatigue based on their eyeball movements. The new device, presented in a paper published in Nature Electronics, can pick up how often a wearer blinks, by tracking changes in a material’s magnetic properties prompted by mechanical stress.
“Our study started with a simple question: how can we monitor fatigue in the real world?” Jing Xu, Ph.D. candidate at UCLA, told Tech Xplore. “We’ve long known that fatigue is more than just feeling tired—it’s a gradual breakdown in how well your body or mind can perform. It creeps in quietly, affecting attention, reaction time, and even physical safety. Yet, measuring fatigue outside of a lab and in a wearable manner has always been a challenge.”
