Performance of a highly sensitive optical waveguide Mach-Zehnder interferometer immunosensor
Abstract
We describe a highly sensitive sensor which uses the evanescent field of a reusable planar optical waveguide as the sensing element. The waveguide used is optimized to obtain a steep dependence of the propagation velocity on the refractive-index profile near the surface. The adsorption of a layer of proteins thus results in a phase change, which is measured interferometrically using a Mach-Zehnder interferometer set-up. The stability of the interferometer is such that phase changes ≈ (1 × 10 ‑2)2π per hour can be measured. Immunoreactions have been monitored down to concentrations of 5 × 10 ‑11 M of a 40 kDa protein.
- Publication:
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Sensors and Actuators B: Chemical
- Pub Date:
- January 1993
- DOI:
- Bibcode:
- 1993SeAcB..10..209H