Open AccessLabel-free biosensing with a multi-box sub-wavelength phase-shifted Bragg grating waveguide
Author(s) -
Enxiao Luan,
Han Yun,
Minglei Ma,
Daniel M. Ratner,
Karen C. Cheung,
Lukas Chrostowski
Publication year - 2019
Publication title -
biomedical optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.362
H-Index - 86
ISSN - 2156-7085
DOI - 10.1364/boe.10.004825
Subject(s) - grating , biosensor , fiber bragg grating , materials science , optics , photonics , waveguide , wavelength , streptavidin , planar , optoelectronics , nanotechnology , physics , chemistry , computer science , biotin , biochemistry , computer graphics (images)
Sub-wavelength grating (SWG) metamaterials have been considered to provide promising solutions in the development of next-generation photonic integrated circuits. In recent years, increasied interest has been paid to silicon photonic planar biosensors based on SWG geometries for performance enhancement. In this work, we demonstrate a highly sensitive label-free phase-shifted Bragg grating (PSBG) sensing configuration, which consists of sub-wavelength block arrays in both propagation and transverse directions. By introducing salt serial dilutions and electrostatic polymers assays, bulk and surface sensitivities of the proposed sensor are characterized, obtaining measured results up to 579.2 nm/RIU and 1914 pm/nm, respectively. Moreover, the proposed multi-box PSBG sensor presents an improved quality factor as high as ∼ 8000 , roughly 3-fold of the microring-based counterpart, which further improves the detection limit. At last, by employing a biotin-streptavidin affinity assay, the capability for small molecule monitoring is exemplified with a minimum detectable concentration of biotin down to 2.28 × 10 - 8M .