Research On Radial Artery Pulse And Respiratory Measurement Using Optical Fiber Sensor

Optical fiber sensors have been widely used in the structures of national largecivil engineering,such as bridge structure,aerospace,oil drilling,power transmission,and so on due tospecial properties of optical fiber like broadband,large capacity,low loss,small size,corrosion resistance,electrical insulation,immune to electromagnetic interference.In addition,the application of optical fiber sensors has been increasingly recognized in the field of biomedical sensing measurement.Compared with electrical sensors,optical fiber sensors don't need a preamplifier,which can be applied in invasive physiological information measurement due to the advantages of small volume.Optical fiber sensor also has the advantages of immune to electromagnetic interference,especially suitable for physiological information detectionunder magnetic resonance imaging(MRI),space and other complicated electromagnetic environment.Therefore,optical fiber sensors show great potential for physiological information detection.The main research aim is to realize the acquisition and analysis of radial artery pulse and respiratory based on the principle of fiber Bragg grating sensing technique,optical fiber's microbend effect and mode interference.The main work of this paper is as follows:Firstly,a theoretical model based on a lever amplification mechanism is constructed and the main factor affecting sensor sensitivity is analyzed due to the weak characteristic of pulse signal.An experimental setup is proposed to test the sensor sensitivity forK values of 6.2:1 and 0.35:1,The results showed that the sensor has higher force sensitivity of 8.236 nm/N when K = 6.2:1.In addition,discussions were carried out on the application of this system to traditional Chinese medicine pulse diagnosis(TCMPD)and experiments were done to measure the pulse waveforms at various pulse-taking positions and depths of the radial artery in the right wrist.The experimental results show that the measurement device is feasible for the applications of traditional Chinese medicine pulse diagnosis.Secondly,a respiration sensor is proposedbased on the principle of microbend effect of optical fiber.The influence of bending radius and turns on bending loss sensitivity is analyzed and experimental demonstrated.The experimental results show that the sensor can obtain the highest bending loss sensitivity when the bending radius is varied in 3-6 mm and bending turns is 4 for 1550 nm light source.As a result,human respiratory acquisition experiments were designed to verify the feasibility of the proposed sensorFinally,a theoretical model based on mode interference is investigated to solve the problem of low measuringsensitivity of fiber optic respiratory sensor.A respiratory sensor based on the principle of mode interference is proposed by cascading the single mode fiber with multimode fiber.The theoretical model principle of the sensor is analyzed and test system is established to measure the sensitivity of the sensor.The experimental results show that the sensor obtained a displacement sensitivity of 53.6 pm/?m.In the end,human respiration measurement experiments were carried out.