Seatbelt-integrated biosensor could reliably track the alertness and stress of pilots and drivers

Over the past decades, electronics and biomedical engineers have developed increasingly sophisticated biosensors, devices that can pick up biological signals from human users. These sensors, which are generally embedded in wearable or implantable technologies, often do not perform as well in settings where users are moving a lot, such as within a vehicle.

Researchers at the National University of Singapore and Tsinghua University have recently developed a new sensor that can pick up and track biological signals, such as the heartbeat and respiration, without being in contact with the body of users. This sensor, presented in a paper published in Nature Electronics, could be used to pick up the cardiopulmonary signals of humans while they are in dynamic and closed environments, such as a plane cabin, a moving car or a bus.

"Monitoring drivers' alertness or stress is essential for road safety," Xi Tian, co-author of the paper, told Tech Xplore. "Existing sensors designed to measure physiological markers of fatigue, such as heart rate and respiration, face challenges in moving vehicles due to the unpredictable vibrational noise. To overcome these challenges, our research focused on developing an automotive biosensor capable of non-contact and reliable health monitoring in dynamic environments."

The biosensor developed by Tian and his colleagues is based on metamaterials, materials that are carefully engineered to enhance or change their properties. To fabricate their sensor, the researchers embroidered conductive threads arranged in a comb-shaped pattern onto a seatbelt, attaining a surface that guides radio waves and amplifies wireless interactions with the human body.

"This design enables the detection of subtle physiological motions through clothing while mitigating environmental noise from vehicle vibrations and other passengers," explained Tian. "Using a signal processing pipeline, our biosensor provides continuous and reliable monitoring of the driver's heartbeat and respiration in a moving vehicle."

The researchers evaluated their sensor's performance in a series of tests, which were carried out in an airline cabin simulator and in a moving car. They found that their seatbelt-integrated sensor conformed to the body of users, while also reliably detecting subtle cardiopulmonary signals even in this dynamic setting.

"We showed that the biosensor's performance was unaffected in a moving vehicle during a 1.5-hour route in Singapore under varied traffic conditions," said Tian. "Additionally, we evaluated the sensor's capability for continuous physiological monitoring in an airplane cabin simulator, where it detected heart rate changes during sleep for sleep-wake detection. These findings underscore the biosensor's potential for continuous and reliable physiological monitoring in various challenging environments."

The new biosensor developed by this team of researchers could soon be further improved and tested in additional real-world scenarios. In the future, it could be integrated into the seatbelts of cars, airplanes and other means of transport, as a way of monitoring the physiological signals of drivers and preventing fatal accidents.

"Our future research will focus on miniaturizing the sensor's radio components and integrating them into compact modules for cost-effective mass production," added Tian. "We also aim to develop algorithms that interpret physiological data to assess fatigue, stress, and driver health status. We plan to collaborate with automotive manufacturers to refine and validate the system in real-world settings."