High sensitivity photonic crystal fiber-based refractive index microbiosensor
Introduction
It is well known that intensive care, monitoring, diagnosing and detecting the disease, drug testing, food safety and environmental field monitoring are considered to be the fore-most concerns in the world. In order to fulfil the above necessities, various fiber optic sensors are reported [1], [2], [3], [4], [5]. Of various sensing techniques, the surface plasmon resonance (SPR) based fiber optic biosensors have gained a considerable attention as they possess the rapid real-time sensing performances [6], [7], [8].
The SPR optical phenomenon has been widely used in various fields, i.e., to study the conformational changes of protein molecules, in the study of biomolecular interactions and in the detection of pesticides [9], [10], [11]. The SPR sensing method employs traditional Kretschmann configuration to excite surface plasmonic waves under a polarized light radiation parallel to the plane of incidence [12]. In a fiber optic SPR sensor probe, a small portion of the cladding is removed in an optical fiber and the unclad portion is coated with a thin metal layer [13]. The outstanding characteristics of SPR optical fiber sensors are admirable sensitivity to the refractive indices of the surrounding dielectric mediums. Generally, the SPR optical fiber sensors have been established in terms of angle modulation in prism-based setup and the wavelength modulation in optical fibers [14]. In recent years, the new class of fiber called photonic crystal fiber (PCF) overcomes the drawbacks posed by the conventional SPR optical sensors. Thus, with the PCF based sensor, one can have the miniaturization of the device, compatibility and portable, rapid and multi-sample testing with sensing performances, etc. [15]. Most importantly, an important condition for optical sensing is so-called phase matching which can be easily achieved in the PCF based SPR sensor by engineering the effective refractive index of the core-guided mode and the plasmonic mode. Recently, a great interest in engineering the geometrical and material properties of the PCF-SPR sensors are numerically investigated with different biological samples to monitor the medical conditions [16].
Diabetes mellitus is a chronic disease which frightens the health and economy of the globe in various developing countries [17]. The consumption of insulin and the role of diet allow the patients to endure a normal life. Nonetheless, a concern of maintaining the glucose levels is essential to control the abiding complications concerned with diabetes. Thus, it is highly essential to regulate the glucose concentration for clinical analysts [18]. In 2009, a glucose fiber optic sensor accordant with changes in the concentration of the liquid for the refractive index variation from 1.3322 to 1.3617 has been reported [19]. An ultrasensitive microfluidic refractive index based photonic crystal fiber sensor with the sensitivity of 30,100 nm/RIU for the refractive index of 1.5 has been reported [20]. A highly sensitive refractometric sensor based on the long period grating in a PCF has exhibited the sensitivity of 1500 nm/RIU for the refractive index of 1.33 [21]. A PCF based refractive index sensor was established with a linear response of 262.28 nm/RIU to analyze the glucose solutions for various refractive index ranges from 1.337 to 1.395 [22]. A long period fiber grating based refractive index sensor has been successfully demonstrated with a maximum sensitivity of 193.42 nm/RIU in the concentrations of glucose-water and glycerol water [23]. A 2D photonic crystal-based biological sensor has been numerically investigated for the detection of glucose concentration from urine with the refractive index range from 1.335 to 1.347 [24]. A photonic crystal with a multi-layered structure has been fabricated for sensing the glucose of various refractive indices with a sensitivity of ∼50.23 nm/RIU and a lower signal-to-noise ratio of ∼0.46 [25]. Recently, the surface plasmon resonance-based D-shaped PCF coated with Indium Tin Oxide at the near-infrared wavelength with high sensitivity of ∼6000 nm/RIU has been reported [26]. By using finite element method, the sensing performance of a D-shaped PCF based refractive index sensor has achieved a high sensitivity of 7700 nm/RIU in the analyte refractive index ranges from 1.43 to 1.46 [27]. In this line, the characteristics of a D-shaped PCF optic sensor was studied with various polishing depths with achieving a sensitivity of 7381.0 nm/RIU in the refractive index range of 1.40–1.42 [28]. Yong Wang et al., have experimentally realized a surface plasmon resonance biosensor based on gold-coated multimode fiber-PCF-multimode fiber obtaining the sensitivity of range from 1060.78 nm/RIU to 4613.73 nm/RIU in the analyte refractive index range of 1.3330–1.3904 [29]. In 2018, a surface plasmon resonance based D-shaped photonic crystal fiber sensor has been reported with a sensitivity of 3340 nm/RIU in the analyte refractive index 1.36–1.38 [30].
In the present study, we report the sensing properties of the PCF based surface plasmon resonance (SPR) refractive index sensor for the application of biomolecular detection. The paper is laid out as follows. In Section 2, we model the proposed PCF based SPR sensor by using the finite element method and analyze the metal influence in the proposed sensor by the Drude-Lorenz model [31]. The metal thickness is varied from 20 to 60 nm and the sensor-balance performance holds good for the thickness of 40 nm. Besides, the metal thickness has been followed as 40 nm for analysing the wavelength and amplitude sensitivities. We report the sensing properties in Section 3. We achieve a maximum wavelength sensitivity of 12,000 nm/RIU with a resolution of 8.33 × 10−5 RIU and amplitude sensitivity of 11,412 RIU−1 with a resolution of 8.76 × 10−8 RIU by varying the refractive index of the analyte. The sensing performances of the proposed device are investigated in terms of sensitivity and detection accuracy. The influence of the geometry parameters of the sensor such as air-hole diameter and metal-layer thickness are investigated in detail in Section 4. Finally, Section 5 concludes the work.
Section snippets
Simulation model and principle
The cross-section and schematic set-up of the PCF based SPR sensor are shown in Fig. 1, Fig. 2. The thickness of the gold layer is varied from 20 to 60 nm. The diameter of the air-holes is 2 µm and pitch is 3 µm. Perfectly matched layer (PML) boundaries are used to calculate the complex propagation constant of the core guided modes. The refractive index of the analyte is varied from 1.31 to 1.45. The analyte refractive index is filled in between the gold layer and PML with a support in four
PCF-RIBS based on SPR
In this section, we numerically investigate the sensing properties of the proposed sensor by using the finite element method. Initially, we calculate the real and imaginary parts of the effective refractive index (neff) as a function of wavelength. Using the imaginary part of neff values, we calculate the confinement loss, α, as shown in Fig. 3 by using the following expression,
In Eq. (1), denotes the imaginary part of the core-guided mode for the
Variations of sensitivity of PCF-RIBS over structural parameters
It is well proven that the fiber-based sensors are highly sensitive over the geometrical structure. Hence, it is necessary to investigate the resonant spectra by varying the geometrical parameters of the proposed PCF-RIBS. In this study, we discuss the influence of two main geometrical parameters, namely, diameter of the air-hole and thickness of the metal layer. First, we analyze the variation of loss spectra by varying the diameter of the air-holes as shown in Fig. 13. It is clear that the
Conclusion
We have numerically demonstrated a PCF-RIBS biosensor to detect biological analyte in the refractive index range of 1.31–1.45. The sensing performances of the proposed PCF-RIBS has been investigated by using the finite element method. We have investigated the loss spectra and dispersion relation between fundamental core-guided mode and plasmonic mode for three different sets of refractive indices of analytes such as 1.31 to 1.35, 1.36 to 1.40 and 1.41 to 1.45. We have been able to achieve the
Funding
National Natural Science Foundation of China (NSFC, 61675008).
References (46)
- et al.
Surface plasmon resonance-based biosensors: From the development of different SPR structures to novel surface functionalization strategies
Curr. Opin. Solid State Mater. Sci.
(2011) - et al.
Fibre optic glucose sensor
Mater. Sci. Eng.: C
(2009) Theoretical analysis of double-microfluidic-channels photonic crystal fiber sensor based on silver nanowires
Opt. Commun.
(2013)- et al.
Multi-hole fiber based surface plasmon resonance sensor operated at near-infrared wavelengths
Opt. Commun.
(2014) - et al.
Plasmonic refractive index sensor employing niobium nanofilm on photonic crystal fiber
IEEE Photonics Technol. Lett.
(2018) - et al.
Fiber Optic Sensors: An Introduction for Engineers and Scientists
(2011) - et al.
Fiber-optic biosensors-trends and advances
Anal. Sci.
(2000) - et al.
Optical fiber sensors for label-free DNA detection
J. Lightwave Technol.
(2017) - et al.
Recent development in optical fiber biosensors
Sensors
(2007) - et al.
Rapid detection of single nucleotide polymorphisms associated with spinal muscular atrophy by use of a reusable fibre-optic biosensor
Nucl. Acids Res.
(2004)
Graphene enhances the sensitivity of fiber-optic surface plasmon resonance biosensor
IEEE Sens. J.
Photonic crystal fiber surface plasmon resonance biosensor based on protein g immobilization
IEEE J. Sel. Top. Quantum Electron.
Detection of conformational changes in an immobilized protein using surface plasmon resonance
Anal. Chem.
Quantification of tight binding to surface-immobilized phospholipid vesicles using surface plasmon resonance: binding constant of phospholipase a2
J. Am. Chem. Soc.
Surface plasmon resonance based fiber-optic sensor for the detection of pesticide
Sens. Actuators, B
Radiative decay of non radiative surface plasmons excited by light
Zeitschrift für Naturforschung A
Optical-fiber strain sensors with asymmetric etched structures
Appl. Opt.
Design of the microstructured optical fiber-based surface plasmon resonance sensors with enhanced microfluidics
Opt. Express
Photonic crystal fiber-based plasmonic sensors for the detection of biolayer thickness
JOSA B
Globalization of diabetes: the role of diet, lifestyle, and genes
Diabetes Care
Diabetes information systems: a rapidly emerging support for diabetes surveil- lance and care
Diabetes Technol. Ther.
Ultrasensitive photonic crystal fiber refractive index sensor
Opt. Lett.
Cited by (17)
Advances in photonic crystal fiber: sensing and supercontinuum generation applications
2022, Optical Fiber TechnologyCitation Excerpt :Khalil et al. explored the titanium nitride as plasmonic metal in a bio-sensing due to its chemical and mechanical stability for temperatures > 2000 °C, highly resistant against corrosion and high melting point [30]. An Au metal-based PCF sensor is demonstrated in the λ range of 0.4–2 μm in the two RI ranges i.e., 1.31–1.35 RIU and 1.41–1.45 RIU [31]. Fan reported Au nano-film coated PCF sensor with enhanced resonance as the coating of first ring of clad is done with Au material and surrounded with fiber core [32].
High sensitivity refractive index sensor based on triple layer MgF<inf>2</inf>-gold-MgF<inf>2</inf> coated nano metal films photonic crystal fiber
2021, OptikCitation Excerpt :However, their obtained sensitivity response was admirable but RI range was comparatively very low. In 2018, Aruna et al. outlined the plasmonic refractive index microbiosensor structure for the detection RI ranges from 1.44 to 1.45 and gained the highest sensitivity of 12,000 nm/RIU [25] which was not high sensitivity response. In the next year, Chen et al. reported a hexagonal PCF structure for the detection RI ranges from 1.32 to 1.38 and achieved the utmost sensitivity of 5500 nm/RIU [26].
Assaying with PCF-based SPR refractive index biosensors: From recent configurations to outstanding detection limits
2020, Optical Fiber TechnologyCitation Excerpt :The use of PCFs for sensing applications has attracted considerable attention and also received massive research efforts in recent decades [11–14]. PCF structures used in sensing applications employ various physical mechanisms such as surface enhanced Raman scattering (SERS) [25], fiber loop mirror (FLM), [26], quartz crystal microbalance (QCM) [27], interferometry [28], quantum dots luminescence [29] directional resonance coupling [30], and surface plasmon resonance (SPR) [12,31] for determining various physicochemical parameters [32–34]. As a result, diverse PCF-based sensors have been proposed and/or fabricated in the form of gas [35], pH [36], humidity [37,38], vibration [39], strain [10], velocity, acceleration, and temperature [40] sensors; microfluidic flow rate, [41] and concentration [42,43] monitors; current [41], voltage [44], electric and magnetic field sensors [30,45] as well as refractive index biosensors (RIBs) [18,46].
Visible to near infrared highly sensitive microbiosensor based on surface plasmon polariton with external sensing approach
2019, Results in PhysicsCitation Excerpt :Consequently, coating the metal on the PCF surface externally turns out to be the best sensing approach. In our previous work, we have numerically investigated a simple structured external sensing PCF-RIBS exhibiting a highest spectral sensitivity of 12,000 nm/RIU and amplitude sensitivity of 11,412 RIU−1 in the RI sensing environment from 1.44 to 1.45 [35]. In this line, to enhance the device performances of the external sensing plasmonic sensors with gold as a coating material, we model two different folds of air-holes such as 6 and 8-fold photonic quasicrystal fiber based refractive index biosensors (PQF-RIBS) using finite element method.
Modelling a simple arc shaped gold coated PCF-based SPR sensor
2024, Journal of Optics (India)