Detection of Hg2+ concentration based on DNA modified LPFG

Ronghao Zhang; Xiaoyang Lei

doi:10.1117/12.2616508

26 July 2022 Detection of Hg²⁺ concentration based on DNA modified LPFG

Ronghao Zhang, Xiaoyang Lei

Proceedings Volume 12279, 2021 International Conference on Optical Instruments and Technology: Optical Sensors and Applications; 122790R (2022) https://doi.org/10.1117/12.2616508
Event: 2021 International Conference on Optical Instruments and Technology, 2022, Online Only

Abstract

A DNA modified long period fiber grating (LPFG) was proposed and fabricated for measurement of mercury ion (Hg²⁺) concentration. The T-T base pair of Hg²⁺ and DNA can specifically bind to form T-Hg²⁺-T complex, which leads to the transition of DNA from irregular free helix conformation to hairpin structure, thereby changing the refractive index of the fiber surface. Firstly, the DNA sequence and coating methods were analyzed and optimized, and the sensing mechanism and phase matching conditions of LPFG were analyzed by using Rsoft. The simulation results showed that reducing the cladding diameter and period could increase the refractive index sensitivity, and changing the length of the gate region would not affect the sensitivity. Besides, the LPFG at the phase matching turning point had higher sensitivity. Then, a CO₂ laser was used to prepare LPFG with a period of 250 μm, and the DNA was fixed on the surface of the grating by electrostatic adsorption with using Poly-L-lysine as the polycation molecule. The results of Hg²⁺ detection experiments showed that when the concentration of Hg²⁺ increased from 6 μM to 18 μM, the resonance wavelength at the trough shifted from 1623.8 nm to 1627.37 nm. There was a linear relationship in the range of 6~12 μM with sensitivity of 0.505 nm/μM. In conclusion, the proposed Hg²⁺ sensor based on DNA modified LPFG structure behaves the advantages of simple production, low cost, and high specificity, which has great potential in the actual environment.

Citation Download Citation

Ronghao Zhang and Xiaoyang Lei "Detection of Hg²⁺ concentration based on DNA modified LPFG", Proc. SPIE 12279, 2021 International Conference on Optical Instruments and Technology: Optical Sensors and Applications, 122790R (26 July 2022); https://doi.org/10.1117/12.2616508

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KEYWORDS

Mercury

Metals

Sensors

Ions

Fiber optics sensors

Refractive index

Cladding

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