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. 2023 Mar 18;13(1):4495.
doi: 10.1038/s41598-023-31127-4.

Ultrasensitive tapered optical fiber refractive index glucose sensor

Erem Ujah #  1   2 , Meimei Lai #  1 , Gymama Slaughter  3   4
Affiliations

Ultrasensitive tapered optical fiber refractive index glucose sensor

Erem Ujah et al. Sci Rep. .

Abstract

Refractive index (RI) sensors are of great interest for label-free optical biosensing. A tapered optical fiber (TOF) RI sensor with micron-sized waist diameters can dramatically enhance sensor sensitivity by reducing the mode volume over a long distance. Here, a simple and fast method is used to fabricate highly sensitive refractive index sensors based on localized surface plasmon resonance (LSPR). Two TOFs (l = 5 mm) with waist diameters of 5 µm and 12 µm demonstrated sensitivity enhancement at λ = 1559 nm for glucose sensing (5-45 wt%) at room temperature. The optical power transmission decreased with increasing glucose concentration due to the interaction of the propagating light in the evanescent field with glucose molecules. The coating of the TOF with gold nanoparticles (AuNPs) as an active layer for glucose sensing generated LSPR through the interaction of the evanescent wave with AuNPs deposited at the tapered waist. The results indicated that the TOF (Ø = 5 µm) exhibited improved sensing performance with a sensitivity of 1265%/RIU compared to the TOF (Ø = 12 µm) at 560%/RIU towards glucose. The AuNPs were characterized using scanning electron microscopy and ultraviolent-visible spectroscopy. The AuNPs-decorated TOF (Ø = 12 µm) demonstrated a high sensitivity of 2032%/RIU toward glucose. The AuNPs-decorated TOF sensor showed a sensitivity enhancement of nearly 4 times over TOF (Ø = 12 µm) with RI ranging from 1.328 to 1.393. The fabricated TOF enabled ultrasensitive glucose detection with good stability and fast response that may lead to next-generation ultrasensitive biosensors for real-world applications, such as disease diagnosis.

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Conflict of interest statement

The authors declare no competing interests.

Figures

Figure 1
Figure 1
Experimental setup for glucose sensing.
Figure 2
Figure 2
(A) UV–Vis spectra of the synthesized gold nanoparticles (AuNPs). (B) Scanning electron microscopy (SEM) of bare and AuNPs-decorated TOF.
Figure 3
Figure 3
Optical spectra of bare TOF sensors in different mass fractions of glucose solutions. (A) TOF (Ø = 5 μm diameter) and (B) TOF (Ø = 12 μm diameter). (C,D) Corresponding normalized intensity spectra.
Figure 4
Figure 4
(A) Optical spectra of AuNPs decorated TOF ( Ø = 12 μm diameter) sensor in different mass fractions of glucose solutions and (B) Corresponding normalized intensity spectra.
Figure 5
Figure 5
(A) Power intensity changes against refractive index of bare TOFs (red and blue) and AuNPs decorated TOF at λ = 1559 nm. (B) Comparison of sensitivity of TOF RI sensors.
Figure 6
Figure 6
Schematic illustration of the heat and pull method for fabricating the tapered optical fiber.
Figure 7
Figure 7
Gold nanoparticle (AuNPs) synthesis by sodium citrate reduction method.
See this image and copyright information in PMC

References

    1. Lai M, Slaughter G. Label-free microRNA optical biosensors. Nanomaterials. 2019;9(11):1573. doi: 10.3390/nano9111573. - DOI - PMC - PubMed
    1. Andryukov BG, Besednova NN, Romashko RV, Zaporozhets TS, Efimov TA. Label-free biosensors for laboratory-based diagnostics of infections: Current achievements and new trends. Biosensors. 2020;10(2):11. doi: 10.3390/bios10020011. - DOI - PMC - PubMed
    1. Armani AM, Kulkarni RP, Fraser SE, Flagan RC, Vahala KJ. Label-free, single-molecule detection with optical microcavities. Science. 2007;317(5839):783–787. doi: 10.1126/science.1145002. - DOI - PubMed
    1. Tazawa H, Kanie T, Katayama M. Fiber-optic coupler based refractive index sensor and its application to biosensing. Appl. Phys. Lett. 2007;91(11):113901. doi: 10.1063/1.2783278. - DOI
    1. Homola J. Surface plasmon resonance sensors for detection of chemical and biological species. Chem. Rev. 2008;108(2):462–493. doi: 10.1021/cr068107d. - DOI - PubMed