Evanescent-wave spectroscopy using an SU-8 waveguide for rapid quantitative detection of biomolecules

Linan Jiang, Karl P. Gerhardt, Brian Myer, Yitshak Zohar, Stanley Pau

Research output: Contribution to journalArticlepeer-review

19 Scopus citations


A 30-mm-long multimode waveguide, 40 μm wide and 40 μm high, is fabricated on a silicon wafer using polymer SU-8 as the core and liquid buffer as the cladding. Antibodies are successfully immobilized on the SU-8 surface designated for binding target antigens dispersed in the buffer solution. Evanescent-wave spectroscopy is performed by exciting the fluorescently labeled antigens, bound to the waveguide surface within its evanescence field, and measuring the emission light intensity. This evanescent-wave biosensor detects specific molecular interaction. The optical output as a function of the antigen concentration can be described by Langmuir equation. Antigen concentration as low as 1.5 μg/mL is detected; concentrations higher than 100 μg/mL lead to sensor saturation. [2008-0058].

Original languageEnglish (US)
Pages (from-to)1495-1500
Number of pages6
JournalJournal of Microelectromechanical Systems
Issue number6
StatePublished - 2008


  • Antibody immobilization
  • Biomolecule binding
  • Evanescent wave
  • SU-8 waveguide

ASJC Scopus subject areas

  • Mechanical Engineering
  • Electrical and Electronic Engineering


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