Characterization of the evanescent field profile and bound mass sensitivity of a label-free silicon photonic microring resonator biosensing platform

Biosens Bioelectron. 2010 Dec 15;26(4):1283-91. doi: 10.1016/j.bios.2010.07.010. Epub 2010 Jul 12.


Silicon photonic microring resonators have emerged as a sensitive and highly multiplexed platform for real-time biomolecule detection. Herein, we profile the evanescent decay of device sensitivity towards molecular binding as a function of distance from the microring surface. By growing multilayers of electrostatically bound polymers extending from the sensor surface, we are able to empirically determine that the evanescent field intensity is characterized by a 1/e response decay distance of 63 nm. We then applied this knowledge to study the growth of biomolecular assemblies consisting of alternating layers of biotinylated antibody and streptavidin, which follow a more complex growth pattern. Additionally, by monitoring the shift in microring resonance wavelength upon the deposition of a radioactively labeled protein, the mass sensitivity of the ring resonator platform was determined to be 14.7±6.7 [pg/mm(2)]/Δpm. By extrapolating to the instrument noise baseline, the mass/area limit of detection is found to be 1.5±0.7 pg/mm(2). Taking the small surface area of the microring sensor into consideration, this value corresponds to an absolute mass detection limit of 125 ag (i.e. 0.8 zmol of IgG), demonstrating the remarkable sensitivity of this promising label-free biomolecular sensing platform.

Publication types

  • Comparative Study
  • Evaluation Study
  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Antibodies
  • Biosensing Techniques / instrumentation*
  • Biosensing Techniques / methods
  • Biosensing Techniques / statistics & numerical data
  • Biotinylation
  • Equipment Design
  • Immunoglobulin G / analysis
  • Iodine Radioisotopes
  • Microscopy, Electron, Scanning
  • Optical Phenomena
  • Photons
  • Sensitivity and Specificity
  • Silicon
  • Static Electricity
  • Streptavidin
  • Surface Plasmon Resonance


  • Antibodies
  • Immunoglobulin G
  • Iodine Radioisotopes
  • Streptavidin
  • Silicon