| For the requirements of important human vital signs measurements,this paper proposes a variety of high-precision sensors to solve the problems of low measurement accuracy,poor wearability,susceptibility to electromagnetic interference,and inaccurate measured waveform information.Based on the fiber Bragg grating sensing principle and the neotype force-sensitive flexible structure deformation theory,three typical sensors including respiratory and heartbeat measurement sensor,carotid signal measurement sensor and radial pulse measurement sensor have been designed and developed for accurate measurement of human vital signs.The specific research contents of this paper are as follows:Firstly,an FBG-based synchronous measurement sensor for breathing and heartbeat movement is proposed.The sensor mainly includes an arc-shaped flexible structure,an FBG sensing element,a silicone film and other fixed connection structures.The overall structure of the sensor is simple in design and convenient for wearable measurement.In order to improve the performance of the designed sensor,the FEM-based method has been utilized to simulate and analyze the static performance of the sensor,and the response surface method has been implemented to optimize the key dimensions of the arc-shaped flexible structure.Besides,the anti-interference ability of the sensor is improved by coating the silica gel film around the optical fiber.Secondly,a high-precision one-dimensional force sensor based on FBG has been proposed to achieve wearable continuous measurement and handheld rapid measurement of carotid pulse.The force sensor is mainly composed of a flexible force-sensitive structure,an FBG element,and other fixed devices.The flexible force-sensitive structure is composed of a pair of parallel-arranged polygonal connecting rod structures,and the optical fiber is arranged perpendicularly to the loading deformation direction of the flexible structure,which realizes a smaller size in loading direction.The excellent static and dynamic measurement performance of the sensor is verified through simulation analysis and optimized design.Thirdly,in order to further realize the quantitative measurement of pulse information,an FBG-based hybrid force and displacement sensor is proposed,which is mainly composed of a force-sensitive orthogonal planar spring structure,an FBG optical fiber,and a sensor frame.The sensor realizes the simultaneous measurement of force and displacement through a suitable flexible element and optical fiber arrangement,and the feasibility of the sensor is verified through theoretical calculation and simulation analysis.The force-displacement hybrid measurement of the sensor can be used to realize the quantitative measurement of the radial artery pulse waveform.Finally,the optimized prototypes of the above three sensors have been manufactured,and the excellent performance of sensors have been verified by force and displacement calibration experiments.Among them,the one-dimensional force sensor used for carotid artery measurement possesses a resolution of 0.65 m N,and the force-displacement hybrid sensor used for radial artery measurement possessed a force resolution of 0.47 m N and displacement resolution of 0.103μm.In addition,several experimental studies have been performed,including respiratory and heartbeat synchronously monitoring experiments,carotid artery pulse waveform measurement under two measurement methods,and radial artery pulse waveform quantitative measurement experiments.The above experiments fully proved the practicality of the designed sensor in the field of human vital signs measurement. |
