Highly Sensitive Aluminum-Based Biosensors using Tailorable Fano Resonances in Capped Nanostructures

Pei Kuen Wei, Hiroaki Misawa, Kosei Ueno, Xu Shi, Ming-Yang Pan, Meng-Lin You, Hsuan-Yeh Hsu, Kuang Li Lee, Chia-Chun Chang

Research output: Contribution to journalArticlepeer-review

42 Scopus citations

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.
Original languageEnglish
Article number44104
JournalScientific Reports
Volume 7
DOIs
StatePublished - 8 Mar 2017

Keywords

  • SURFACE-PLASMON DETECTION; GOLD NANOSLIT ARRAYS; NANOHOLE ARRAYS; LIGHT TRANSMISSION; METAMATERIALS; SENSORS; FILMS; SPECTROSCOPY; GENERATION; MICROSCOPY

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