title: Chip-based digital surface plasmon resonance sensing platform for ultrasensitive biomolecular detection.
abstract: A chip-based ultrasensitive surface plasmon resonance (SPR) sensor in a checkerboard nanostructure on plastic substrates is presented for digital detection. The sensing elements on the checkerboard are composed of silver-capped nanoslit arrays, which were fabricated using the thermal-embossing nanoimprint method, to meet the demand for low-cost and rapid fabrication. Sharp Fano resonances in the optimized nanoslit arrays provide high-intensity sensitivities (20,000% per refractive index unit), with an element size of 12.5µm. The polarization-dependent transmission in the checkerboard pattern produces optical isolation between sensing elements and results in a crosstalk lower than 1%. Protein-antibody experiments demonstrated that the digital detection limit was up to 1pg/mL, which is approximately 1000 times lower than that of conventional analog detection. For a 140µm×140µm checkerboard pattern, the dynamic range was approximately 100 times higher than that of conventional surface plasmon resonance measurements. This new digital detection method is very useful for detecting ultralow concentrations of analytes with a nonuniform distribution on the sensor surface.
authors.affiliation: Research Center for Applied Sciences, Academia Sinica, No. 128, Section 2, Academic Road, Taipei 11529, Taiwan; Institute of Photonics Technologies, National TsingHua University, No. 101, Section 2, Kuang-Fu Road, Hsinchu 30013, Taiwan.
authors.forename: Ming-Yang
authors.initials: MY
authors.lastname: Pan
authors.affiliation: Research Center for Applied Sciences, Academia Sinica, No. 128, Section 2, Academic Road, Taipei 11529, Taiwan.
authors.forename: Kuang-Li
authors.initials: KL
authors.lastname: Lee
authors.affiliation: Institute of Photonics Technologies, National TsingHua University, No. 101, Section 2, Kuang-Fu Road, Hsinchu 30013, Taiwan.
authors.forename: Likarn
authors.initials: L
authors.lastname: Wang
authors.affiliation: Research Center for Applied Sciences, Academia Sinica, No. 128, Section 2, Academic Road, Taipei 11529, Taiwan; Institute of Biophotonics, National Yang-Ming University, No. 155, Sec. 2, Linong Street, Taipei 112, Taiwan; National Taiwan Ocean University, Department of Optoelectronics, Beining Rd., Jhongjheng District, Keelung 202, Taiwan. Electronic address: pkwei@sinica.edu.tw.
authors.forename: Pei-Kuen
authors.initials: PK
authors.lastname: Wei
mesh_terms: D000818:Animals; D000906:Antibodies / Q000032:analysis; D002417:Cattle; D004867:Equipment Design; D056656:Lab-On-A-Chip Devices; D049329:Nanostructures / Q000737:chemistry / Q000648:ultrastructure; D012710:Serum Albumin, Bovine / Q000032:analysis; D020349:Surface Plasmon Resonance / Q000295:instrumentation*
chemical_list: D000906:Antibodies; D012710:Serum Albumin, Bovine
keywords: Digital detection; Fano resonance; Nanostructure; SPR imaging; SPR sensor; Surface plasmon resonance