Scientists have developed a new wearable device that functions like a “polygraph,” but instead of detecting lies, it monitors stress levels in adults and infants, according to a study published in the journal Science Advances.

Unlike traditional approaches, the new technology is designed to detect hidden physiological signs of stress that the body may exhibit even before a person becomes consciously aware of their condition.

According to the study’s lead author, Professor John Rogers of Northwestern University, prolonged stress can negatively affect health, especially in pregnant women, children, and critically ill patients.

The device is a lightweight wearable sensor resembling a patch that is attached to the chest and monitors heart rate, breathing, sweating, blood flow, and body temperature in real time. In this way, the system captures complex physiological responses associated with stress.

The technology was originally developed at the request of pediatricians from Ann & Robert H. Lurie Children's Hospital of Chicago to monitor stress levels in infants during treatment. Currently, assessments of children’s condition are often based on subjective observations — such as crying, facial expressions, and movements — which can make diagnosis inaccurate.

The researchers emphasize that the new device eliminates subjectivity and enables continuous monitoring of a patient’s condition throughout the day, recording not only the presence of stress but also its intensity and duration. According to them, this could help doctors and patients evaluate the effectiveness of stress-reduction methods.

During testing, the device detected increased stress responses during difficult tasks, answers to sensitive questions, and exposure to cold water. Training sessions for medical personnel also revealed that higher stress levels correlated with poorer decision-making in extreme situations.

In the future, the researchers plan to expand testing and further improve the technology, including adding the ability to monitor brain activity in order to better distinguish between stress and pain.