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The invention relates to a spiral fiber strain sensor for self-powered human respiratory monitoring

Panahon:2022-02-28 Mga hit:

Respiration, as one of the vital signs of human health monitoring, contains a lot of physiological information about individual health and potential diseases. Real-time monitoring of breathing can spot potential disease risks and even save lives. In view of the shortcomings of most respiratory monitoring equipment, such as complex and bulky, not suitable for portable and real-time monitoring, it is of great significance to develop self-powered and wearable real-time respiratory monitoring system.
A self-powered smart wearable real-time respiratory monitoring system based on a self-powered spiral fiber strain sensor (HFSS) has been developed at the Beijing Institute of Nanoenergy and Systems, Chinese Academy of Sciences. The system can measure some key respiratory parameters for disease prevention and medical diagnosis. The smart alarm can automatically call a preset mobile phone for help according to changes in human breathing behavior.




Researchers choose commercial silver plated polyamide fiber as electrode, choice of polytetrafluoroethylene (PTFE) fiber and polyamide fiber as triboelectric material, through the fiber cladding core-shell method to conceal silver plated polyamide fiber woven PTFE fiber and polyamide fiber winding silver plated polyamide fiber woven fiber winding alternately on fiber base material can be stretched, PTFE fiber or polyamide fiber used as shell, silver plating fiber as the core layer. The shell fiber is wound around the core fiber, and the two are intertwined. The contact separation of two triboelectric layers (PTFE and nylon) can be realized by the tension release motion of the sensor. During the tensile process, the helix elongates along the longitudinal direction, and the adjacent nylon and PTFE separate until the maximum tensile strain is reached.




The working principle of the sensor is based on the coupling contact electrification and electrostatic induction of two triboelectric materials (PTFE and nylon). Due to the opposite triboelectric polarities of PTFE and nylon, their surfaces will induce equivalent positive and negative triboelectric charges. Once the sensor is stretched by an external force, the contact surfaces begin to separate, creating a potential difference between the two surfaces that drives the free electrons. By studying the effect of tensile strain on the electrical output of the sensor, it is found that the open-circuit voltage, short-circuit current and short-circuit charge transfer all increase with the increase of tensile strain. When the tensile strain is 1%, the sensor still has a stable voltage output of 0.5V, which is very sensitive to strain.




The researchers integrated a self-powered strain sensor into the chest band and attached it below the chest to monitor breathing. As the chest expands or contracts, the sensors expand and contract regularly. Through the calculation and processing of these electrical signals, human respiration rate, forced vital capacity, peak expiratory flow and other indicators can be obtained. Dugang pa, researchers have developed a smart wearable real-time respiratory monitoring system that includes a smart spirometer and a self-powered smart alarm. The smart spirometer can quantify the air flow per exhalation and initially diagnose respiratory diseases. The smart alarm will automatically call the preset phone for help when the subject stops breathing for more than 6 seconds.

 


The research provides an effective spiral structure for manufacturing highly sensitive strain sensors based on friction nanogenerators and develops a wearable self-powered real-time respiratory monitoring system, showing great potential in personal respiratory health monitoring and smart wearable medical electronics. "Helical Fiber Strain Sensors Based on Triboelectric Nanogenerators for self-powered Human Respiratory system Monitoring was published in ACS Nano.