Research And Application Of Wearable Fabric Pressure Sensing Based On Triboelectric Nanogenerator

As society progresses and the pace of human life continues to accelerate,the morbidity and mortality of cardiovascular disease and sleep apnea syndrome rise rapidly,becoming a significant factor threatening human health.Respiratory and pulse signals are the key indicators for the detection and diagnosis of these diseases.Therefore,monitoring of respiration and pulse signals can detect abnormalities in physical condition in advance and prevent it in time.However,most of the clinical detection methods are not suitable for long-term monitoring because of their expensive price and heavy equipment.Therefore,wearable system,as an emerging and effective health monitoring method,can realize real-time and continuous monitoring of vital signs such as respiration and pulse.However,at present,traditional flexible wearable electronics need to be supported by the substrate,moreover,they need to be fixed on the skin with adhesive tape or band-aids.Long-term use may cause skin discomfort.In order to improve the comfort and air permeability of wearable electronics in daily use,smart electronic textile as an ideal flexible device has entered people’s vision.The existing electronic textiles have some disadvantages such as low sensitivity,slow response time and single physiological parameters.To this end,the following studies are conducted in this paper:(1)In this paper,a fabric wearable multi-function pressure sensor based on triboelectric nanogenerator is studied.The sensor is knitted by a full cardigan stitch method using special conductive yarns and a common nylon yarns,and its working mechanism is based on a single-electrode triboelectric nanogenerator.Moreover,the textile sensor can be knitted by an industrial computer flat knitting machine and can be sewn into different parts of a piece of clothing according to the requirements.According to the working principle of the triboelectric nanogenerator and the structural design of the sensor,the electrical output characteristics and force distribution of the sensor were simulated by COMSOL.(2)The electrical output performance of the textile sensor was tested.By combining different specifications of the conductive and nylon yarn,the combination with the largest output voltage is found and tested for subsequent tests.Then we test the maximum output of the textile sensor by changing the tightness of the fabric per unit area and take the above specification and tightness as the manufacturing standard of the sensor.The above specifications and tightness were used as the manufacturing standards of our textile sensor,and the sensitivity,response time,stability and washability of the sensor were tested respectively.After testing,the textile sensor has higher sensitivity and lower response time.When the external pressure is less than 3N,the sensitivity is7.84 m V/Pa;the response time is 20 ms,which verifies the feasibility of its application to health monitoring.(3)The textile sensor is used to monitor the pulse signal of different parts of the body,and the signal is further analyzed and calculated to determine whether the tester has cardiovascular disease.We sew the textile sensor on the neckband,wristband,elbow pads,socks,or make a fingertip to monitor the pulse signal at the neck,wrist,arm,ankle,and fingers.The pulse waveforms of two different parts are simultaneously measured by the dual-channel circuit system,and the value of the pulse wave velocity(PWV)is calculated.Compared with the normal range,the testers were judged whether have cardiovascular disease.(4)we stitch the textile sensor into a sweater to form a piece of smart clothing.Then we monitor the respiratory and pulse signals simultaneously to determine whether the tester has sleep apnea syndrome.The sensors are stitched on the front and cuffs of the clothing,allowing the tester to sleep in the smart clothing with sensors.Using the smart clothing,we monitor the changes in respiration and pulse waveforms while they sleep.Based on these two waveforms,we can determine whether the tester has sleep apnea syndrome.The subsequent analysis and processing of the acquired waveform can determine the severity and type of sleep apnea syndrome.