Development of a wearable device for breathing rate monitoring using stretchable sensors

In recent years, Wearable Devices (WDs) have gained growing interest in detection of human vital parameters, from simple activity trackers to more complex systems capable of providing active interaction with the human body. This is also due to the spread of IoT systems, which allow the efficient data processing provided by various devices. Despite the development of even smaller and more powerful rigid electronic devices, the spread of stretchable sensors has attracted attention because of their skin-like characteristics, their multiple application fields and their environmental impact. A wearable device using flexible and stretchable sensors, based on strain-response mechanism, to monitor breathing rate is designed and analyzed in this research study. The impedance variation has been evaluated connecting two evaluation boards with a stretchable sensor, developed by Uppsala University. The STM32CubeMX software and the µVision®5 IDE, property of ARM, have been use to program the MCU. The performance of the developed device is evaluated in several body positions: sitting, standing and walking. The acquired sensing signals are then filtered and breathing parameters are extacted on Matlab R2021a. Afterwards, the related final results are discussed and compared with those extracted from the Pulse Sense device, a wearable device developed by STMicroelectronics. Statistical analysis are performed and confirm that there is no significant difference between the measurements acquired by the devices. The stretchable sensor used shows high stretchability, and excellent fit for wearable applications, leading to the possibility of further integration into more complex wearable sensing systems.