Research On Key Technologies Of Wearable Optical Fiber Human Vital Signs Monitoring Smart Clothing

Most of the development of wearable sensors is based on the principle of electric induction.These sensors measure the changes of electrical characteristics such as resistance,current and voltage,and are usually sensitive to electromagnetic interference.Fiber Bragg grating(FBG)is a very important optical device,which has been widely used in aviation,aerospace,chemical industry,electric power,ship,coal mine,civil engineering and other fields.Compared with wearable electronic sensors,fiber Bragg grating sensors naturally have the advantages of good safety performance,no electromagnetic interference,high sensitivity,light weight,small volume,easy reuse(Networking),etc.,especially the compatibility between fiber and fabric fiber,which makes it a real wearable "fabric sensor" and improves the wearing comfort.Therefore,fiber Bragg grating sensor is an ideal sensor in wearable applications.This thesis is based on the research contents and objectives of National Natural Science Foundation of China and Tianjin key R &D program.The main research contents and important achievements of this thesis are as follows:1.Fiber Bragg grating temperature sensor and heart sound sensor are designed and developed.The bare fiber Bragg grating(FBG)was packaged with the terpolymer of acrylonitrile,butadiene and styrene to enhance the temperature sensitivity.The FBG was bonded to the vibration diaphragm,and the resin shell of heart sound was made by3 D printing technology to enhance the heart sound picking effect.The design results show that the size of the temperature sensor is 25 × 4 × 2mm,and the temperature sensitivity coefficient can reach 53 pm / ?;the outer diameter of the packaged heart sound sensor is 38 mm,and the thickness is 4.5mm.The fiber Bragg grating sensor is implanted into the fabric by means of double-layer hollow cloth to ensure the coordinated movement of the sensor and the fabric.2.A narrow-band demodulation scheme combining edge filtering demodulation method and arrayed waveguide grating demodulation method is proposed,which can realize the detection of human body temperature signal in wearable fiber Bragg grating smart clothing under narrow-band light source;on the basis of this scheme,the wavelength demodulation range can be widened by increasing the number of narrowband light sources,and the detection of human heart sound signal can be realized.3.Based on the demodulation circuit of optical waveguide grating array,the signal acquisition and demodulation system is designed.The experimental results show that the temperature detection range is 35 ? 42 ?,and the error is ± 0.1 ?;the system can detect the heart sound signal mainly concentrated in the frequency range of 50 ? 100 Hz,recognize the first and second heart sound,and calculate the characteristic parameters such as cardiac cycle,heart rate,S1 average time limit,S2 average time limit and cardiac force,so as to realize the detection of human heart sound signal.