A team of researchers at the National University of Singapore and Tsinghua University has created a sensor that detects and tracks biological signals — such as heartbeat and respiration — without being in contact with the body of the wearer.

According to its developers, the sensor can detect the cardiopulmonary signals of humans while they are in dynamic and closed environments — such as a plane cabin or a moving car or a bus, for instance.

Source: Zeng et al.

"Monitoring drivers' alertness or stress is essential for road safety. 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 researchers explained.

To create the biosensor, the researchers embroidered conductive threads in a comb-shaped design onto a seatbelt, creating a surface that guides radio waves and amplifies wireless interactions with the human body, the researchers explained.

The design reportedly allows for the detection of subtle physiological motions through clothing while lessening the environmental noise from vehicle vibrations and other passengers. Leveraging a signal processing pipeline, the researchers explained that the biosensor ensures continuous and reliable monitoring of the driver's heartbeat and respiration while the vehicle is in motion.

Through a series of tests, the researchers assessed the sensor's performance in an airline cabin simulator and in a moving car and determined that the seatbelt-integrated sensor conformed to the body of users and reliably detected subtle cardiopulmonary signals even in dynamic settings.

"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," the researchers explained. "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 researchers propose that the biosensor could eventually be incorporated into seatbelts in cars, airplanes and other modes of transportation to monitor drivers' physiological signals, potentially preventing fatal accidents.

An article detailing the technology, “A digitally embroidered metamaterial biosensor for kinetic environments,” appears in the journal Nature Electronics.