1. Highly Sensitive Aluminum-Based Biosensors using Tailorable Fano Resonances in Capped Nanostructures
- Author
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Pei-Kuen Wei, Kuang-Li Lee, Hiroaki Misawa, Meng-Lin You, Ming-Yang Pan, Hsuan-Yeh Hsu, Kosei Ueno, Chia-Chun Chang, and Xu Shi
- Subjects
Physics::Biological Physics ,Multidisciplinary ,Nanostructure ,Materials science ,Physics::Optics ,Fano resonance ,Metamaterial ,chemistry.chemical_element ,Nanotechnology ,02 engineering and technology ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,021001 nanoscience & nanotechnology ,01 natural sciences ,Article ,Highly sensitive ,010309 optics ,Condensed Matter::Materials Science ,Mathematics::Algebraic Geometry ,chemistry ,Aluminium ,0103 physical sciences ,Microscopy ,0210 nano-technology ,Spectroscopy ,Biosensor - Abstract
Metallic nanostructure-based surface plasmon sensors are capable of real-time, label-free, and multiplexed detections for chemical and biomedical applications. Recently, the studies of aluminum-based biosensors have attracted a large attention because aluminum is a more cost-effective metal and relatively stable. However, the intrinsic properties of aluminum, having a large imaginary part of the dielectric function and a longer evanescent length, limit its sensing capability. Here we show that capped aluminum nanoslits fabricated on plastic films using hot embossing lithography can provide tailorable Fano resonances. Changing height of nanostructures and deposited metal film thickness modulated the transmission spectrum, which varied from Wood’s anomaly-dominant resonance, asymmetric Fano profile to surface plasmon-dominant resonance. For biolayer detections, the maximum surface sensitivity occurred at the dip of asymmetric Fano profile. The optimal Fano factor was close to −1.3. The wavelength and intensity sensitivities for surface thickness were up to 2.58 nm/nm and 90%/nm, respectively. The limit of detection (LOD) of thickness reached 0.018 nm. We attributed the enhanced surface sensitivity for capped aluminum nanoslits to a reduced evanescent length and sharp slope of the asymmetric Fano profile. The protein-protein interaction experiments verified the high sensitivity of capped nanostructures. The LOD was down to 236 fg/mL.
- Published
- 2017
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