A newly developed measuring device will make it easier in the future to record movement behavior, breathing rate, and pulse. The wireless and batteryless measuring device adheres to the skin like an adhesive bandage.
The skin can reveal a lot about someone’s health. Physical and emotional reactions such as stress, excitement, frustration or anger can manifest in this human organ. USA researchers have now developed a measuring device that does not require batteries, cables or chips to detect these signals on the skin.
Professor Zhenan Bao and her team at Stanford University, California have developed a device that adheres to the skin like an adhesive bandage. The device measures how the skin expands and contracts. This information is transmitted wirelessly to a receiver on the wearer's clothing. Using the measurements, the researchers were able to determine breath, pulse and the movement of arms and legs.
The researchers named their invention BodyNET or "Body Area Sensor Network". They define the measuring device as a "collection of networked sensors that can be used to determine physiological signals in humans". The device was tested by gluing the sensors to the participants' wrists and bellies to measure pulse and respiration.
By attaching these patches to elbows and knees, the researchers were able to determine when a person is moving. The patch detected expansions and contractions in the skin areas that responded to muscle movements.
BodyNET uses the same RFID technology (radio-frequency identification) that is also used for keyless access systems or keycards. As part of their research, the team had to find a way to send RFID energy through an antenna that could expand, contract and bend with the skin.
Initially, the research team used metallic ink to build the antenna. It was found, however, that the signal was not strong enough to keep up with the constant movement of the antenna and skin. Therefore, the team developed a stronger RFID system that also uses Bluetooth technology. This made it possible to transmit the measured values directly to a smartphone or other wireless receivers.
The research team hopes that the newly developed patch can be used in the future to monitor patients with sleep disorders and heart disease. The next step will be to find out how the device can also measure sweat and body temperature. Professor Bao hopes that in the future “it will be possible to create a sensor for the whole skin, to collect physiological data without affecting a person's normal behavior".
A wireless body area sensor network based on stretchable passive tags
Simiao Niu, Naoji Matsuhisa, Levent Beker, Jinxing Li, Sihong Wang, Jiechen Wang, Yuanwen Jiang, Xuzhou Yan, Youngjun Yun, William Burnett, Ada S. Y. Poon, Jeffery B.-H. Tok, Xiaodong Chen & Zhenan Bao
Nature Electronics Volume 2, pages 361–368 (2019)