title: Ultrasensitive biosensors using enhanced Fano resonances in capped gold nanoslit arrays.
abstract: Nanostructure-based sensors are capable of sensitive and label-free detection for biomedical applications. However, plasmonic sensors capable of highly sensitive detection with high-throughput and low-cost fabrication techniques are desirable. We show that capped gold nanoslit arrays made by thermal-embossing nanoimprint method on a polymer film can produce extremely sharp asymmetric resonances for a transverse magnetic-polarized wave. An ultrasmall linewidth is formed due to the enhanced Fano coupling between the cavity resonance mode in nanoslits and surface plasmon resonance mode on periodic metallic surface. With an optimal slit length and width, the full width at half-maximum bandwidth of the Fano mode is only 3.68 nm. The wavelength sensitivity is 926 nm/RIU for 60-nm-width and 1,000-nm-period nanoslits. The figure of merit is up to 252. The obtained value is higher than the theoretically estimated upper limits of the prism-coupling SPR sensors and the previously reported record high figure-of-merit in array sensors. In addition, the structure has an ultrahigh intensity sensitivity up to 48,117%/RIU.
authors.affiliation: 1] Research Center for Applied Sciences, Academia Sinica, Taipei 11529, Taiwan [2] Institute of Physics, Academia Sinica, Taipei 11529, Taiwan.
authors.forename: Kuang-Li
authors.initials: KL
authors.lastname: Lee
authors.affiliation: Department of Mechanical and Mechatronic Engineering, National Taiwan Ocean University, Keelung 20224, Taiwan.
authors.forename: Jhih-Bin
authors.initials: JB
authors.lastname: Huang
authors.affiliation: Institute of Biophotonics, National Yang-Ming University, Taipei 11221, Taiwan.
authors.forename: Jhih-Wei
authors.initials: JW
authors.lastname: Chang
authors.affiliation: 1] Research Center for Applied Sciences, Academia Sinica, Taipei 11529, Taiwan [2] Institute of Biophotonics, National Yang-Ming University, Taipei 11221, Taiwan.
authors.forename: Shu-Han
authors.initials: SH
authors.lastname: Wu
authors.affiliation: 1] Research Center for Applied Sciences, Academia Sinica, Taipei 11529, Taiwan [2] Institute of Biophotonics, National Yang-Ming University, Taipei 11221, Taiwan [3] Department of Optoelectronics, National Taiwan Ocean University, Keelung 20224, Taiwan.
authors.forename: Pei-Kuen
authors.initials: PK
authors.lastname: Wei
mesh_terms: D015374:Biosensing Techniques / Q000295:instrumentation / Q000379:methods*; D006046:Gold / Q000737:chemistry*; D046228:Microarray Analysis; D018625:Microscopy, Atomic Force; D049329:Nanostructures / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry; D012825:Silicon / Q000737:chemistry; D020349:Surface Plasmon Resonance
chemical_list: D011108:Polymers; D006046:Gold; D012825:Silicon