In a recent publication in the journal Heliyon, researchers introduced a cutting-edge wheel-shaped exposed core Localized Surface Plason Resonance - Photonic Crystal Fiber (LSPR-PCF) sensor designed for dual-peak sensing. This sensor, ideal for optical communication and biosensing, features a unique structure with just three air holes and plasmonic materials deposited at precise angles. It shows promising potential for detecting a broad range of biomolecules and biochemicals across a wide spectrum.
(a) 2-dimensional and (b) 3-dimensional layout of our proposed design. Image Credit: https://www.sciencedirect.com/science/article/pii/S2405844024092557
The LSPR-PCF Sensor
The design of the wheel-shaped exposed core LSPR-PCF sensor is characterized by its streamlined architecture, which integrates plasmonic materials such as Indium Tin Oxide (ITO), silver, and titanium dioxide to boost its sensing effectiveness.
The use of ITO is particularly noted for its high carrier concentrations, minimal loss in the infrared spectrum, and tunable photoelectric properties, making it an integral part of the sensor's construction. Silver is preferred over gold for its cost-effectiveness and superior quality factor performance, which are crucial for enhanced sensor functionality.
The fabrication of this sensor involved a series of meticulous steps to ensure its optimal performance and reliability for dual-peak sensing applications. This process included the strategic placement of plasmonic materials and coatings to amplify the sensor's capabilities.
The sensor's core structure features three air holes arranged 120° apart in a wheel shape, a design that not only facilitates manufacturing ease but also maximizes the efficiency of sensing. The precise deposition of plasmonic materials such as ITO and a bimetallic layer of silver and titanium dioxide on specific areas of the sensor ensures the achievement of optimal optical properties.
Assessing the Sensor Performance
The choice of materials played a crucial role in determining the sensor's performance characteristics. ITO was selected for its high carrier concentrations, minimal infrared loss, and tunable photoelectric properties, contributing significantly to the sensor's sensitivity to refractive index changes. The use of silver as a plasmonic material offered cost-effectiveness and superior quality factor performance compared to other metals.
To enhance the sensor's sensing parameters, a bilayer consisting of TiO2/Graphene over Gold/Silver-based sensors was incorporated. This integration not only provided protection against oxidation but also improved adhesion, leading to enhanced sensing capabilities. The combination of TiO2/Au/Graphene in the sensor design further amplified its sensitivity to refractive index variations.
The sensor's performance was evaluated through rigorous numerical simulations analyzing its response to different refractive indices and wavelengths. The simulations helped optimize the sensor specifications to achieve maximum wavelength sensitivity (WS) and double peak shift sensitivity (DPSS), crucial for accurate and reliable sensing applications.
Experimental validation of the sensor's performance was conducted to verify the numerical simulation results and assess the sensor's real-world sensing capabilities. The sensor demonstrated high precision in detecting changes in analyte refractive indices, showcasing its accuracy and reliability in practical applications.
The optical characteristics of the wheel-shaped exposed core LSPR-PCF sensor, such as resonant wavelength shifts and amplitude sensitivity, were thoroughly examined to evaluate its response to changes in refractive indices. The sensor's distinctive structural configuration and the application of plasmonic material coatings played a crucial role in enabling dual-peak sensing and achieving high levels of sensitivity. These features are key to the sensor's effectiveness in applications that require precise detection of biomolecular changes, enhancing its utility in both optical communication and biosensing domains.
Results and Discussion
The experimental analysis of the wheel-shaped exposed core LSPR-PCF sensor showcased its impressive dual-peak sensing capabilities and its high sensitivity to changes in the refractive index, enhancing its utility in both optical communication and biosensing applications.
The sensor's unique design, which includes three air holes coated with plasmonic materials, facilitates the generation of dual resonance peaks within specific refractive index ranges. This feature is critical for boosting the sensor’s sensitivity to wavelength variations and enhancing its accuracy in detecting biomolecules and biochemicals.
Performance metrics of the sensor are particularly noteworthy, with the wavelength sensitivity (WS) reaching 50,652 nm/RIU and a remarkable double peak shift sensitivity (DPSS) of 50,000 nm/RIU. These figures highlight the sensor's exceptional ability to detect minute changes in refractive indices, underscoring its potential for precise analytical applications.
The selection of plasmonic materials, such as Indium Tin Oxide (ITO), silver, and titanium dioxide, is pivotal in augmenting the sensor's performance. ITO’s high carrier concentrations, cost-effectiveness, and superior quality factor of silver particularly enhance the sensor’s sensitivity and detection accuracy.
Overall, the sensor's optical properties, including resonant wavelength shifts and amplitude responses, were meticulously analyzed to ascertain its response under varying refractive index conditions. The dual-resonance phenomenon, enabled by the strategic use of plasmonic coatings, allows for the precise detection of refractive index changes, establishing the sensor as a valuable asset for a wide range of sensing applications.
Conclusion
In conclusion, the wheel-shaped exposed core LSPR-PCF sensor presents a promising advancement in biosensing and optical communication applications. Its dual-peak sensing capability, high precision in detecting refractive index changes, and ease of fabrication make it a valuable tool for telecommunications and medical engineering. The sensor's exceptional sensing parameters and unique structural features set it apart as a potential biosensor with diverse applications in various industries.
Journal Reference
Mohammad Rakibul I., Ali Ahnaf H., et al. (2024). A unique wheel-shaped exposed core LSPR-PCF sensor for dual-peak sensing: Applications in the optical communication bands, M-IR region and biosensing, Heliyon 10, 13. DOI: 10.1016/j.heliyon.2024.333224, https://www.sciencedirect.com/science/article/pii/S2405844024092557