Design And Sensing Characteristics Of Fiber Optic Arginine Sensor

Arginine is one of the most basic amino acids for protein synthesis in human body,and is an important substance for growth hormone synthesis and immune system.Lack of arginine can lead to slow growth hormone synthesis in children,affecting development;It can also lead to a decrease in synthesis in adults and lower resistance.Therefore,it is of great significance for high precision detection and specific recognition of arginine concentration.In this paper,a long period fiber Bragg grating arginine sensor and a tilted fiber Bragg grating arginine sensor are designed and fabricated,and their sensing characteristics are experimentally studied.In this paper,a combination of theory and experiment is adopted.Firstly,theoretical analysis is carried out on the long-period fiber grating and tilted fiber grating,and then the sensitivity,stability and repeatability of the two sensors in the detection of temperature,refractive index and arginine solution are explored respectively.Secondly,magnetron sputtering vacuum coating machine was used to stimulate SPR effect by sputtering a layer of gold film on the outer surface of two sensor grating sensitive areas,and the sensing characteristics were studied experimentally.The experimental results show that SPR effect can improve the detection sensitivity of the sensor.The sensitivity of long-period fiber Bragg grating sensor with SPR effect is increased from 43.22pm/℃ to 170.95pm/℃.The refractive index sensitivity was increased from-186.02nm/RIU to-434.39nm/RIU.The detection sensitivity of arginine solution was increased from 3.4nm/μM to5.22nm/μM.The sensitivity of the inclined fiber Bragg grating sensor with SPR effect is increased from 22.86pm/℃ and 19.71pm/℃ to 71.9pm/℃ and 72.62pm/℃.The refractive index sensitivity was increased from 184.87nm/RIU to 487.4nm/RIU.The detection sensitivity of arginine solution was increased from 2.33nm/μM to7.14nm/μM.Finally,by analyzing the characteristics of the optical fiber sensor after sputtering gold layer and the chemical properties of arginine,11-mercaptoundecanoic acid was selected as the sensor probe layer to improve the detection sensitivity of the two optical fiber sensors to arginine molecules in solution.The detection sensitivity of long-period fiber Bragg grating arginine sensor coated with probe layer is increased from 3.4nm/μM to 7.20nm/μM.The detection sensitivity of tilted fiber Bragg grating arginine sensor was increased from 2.33nm/μM to 9.57nm/μM.In order to further prove that the sensor coated with 11-mercaptoundecanoic acid has specific recognition function for arginine molecules in solution,the sensor characteristics of three kinds of mixed solutions containing arginine were investigated experimentally using two kinds of selective sensors.The experimental verification showed that the specific recognition ability of the sensor was roughly the same as that of the standard solution detection.