Paper
3 May 2013 Migrating the Mach-Zehnder chemical and bio-sensor to the mid-infrared region
L. Leidner, M. Ewald, M. Sieger, B. Mizaikoff, G. Gauglitz
Author Affiliations +
Abstract
The properties of integrated optical phase-modulated Mach-Zehnder interferometers (IO-MZI) are used to set up a new generation of chemical and biochemical sensors working in the mid-infrared. First applications of the MZI principle were introduced in the beginning 1990s. They range from a gas sensor to monitor organic solvent concentrations1 to setting up an immunoassay for the detection of the herbicide simazine2. Most if not all sensors of MZI type operate at wavelengths of the visible or near infrared spectrum. There are several reasons to change this strategy and move into the mid-infrared spectral range (MIR): higher manufacturing tolerances, increased evanescent field penetration depth, signal amplification by surface enhanced infrared absorption effect (SEIRA), species identification by MIR fingerprints. The basis of the planned MIR-MZI is a GaAs waveguide pattern epitaxially grown on a substrate3. As a first step towards nanostructuring the waveguide surface, chemical deposition of Au nanoparticles on GaAs transducers was established. For the use of MIR-MZI sensors in bioanalytical assay development, chemical immobilization of molecular recognition elements on GaAs transducers was carried out. The modified surfaces were characterized by atomic force microscopy (AFM), dark field microscopy, contact angle measurements and ellipsometric data as well as by a modified version of Reflectometric Interference Spectroscopy (RIfS)4. It was possible to monitor both the immobilization of gold nanoparticles and time-resolved specific binding using a model antibody antigen assay. After successful setup of relevant assays with RIfS, e.g. the detection of bacteria or endocrine disruptors, the assays are designed to be transferred onto the mid-infrared Mach-Zehnder interferometer.
© (2013) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
L. Leidner, M. Ewald, M. Sieger, B. Mizaikoff, and G. Gauglitz "Migrating the Mach-Zehnder chemical and bio-sensor to the mid-infrared region", Proc. SPIE 8774, Optical Sensors 2013, 87740S (3 May 2013); https://doi.org/10.1117/12.2017387
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Cited by 6 scholarly publications.
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KEYWORDS
Sensors

Gallium arsenide

Waveguides

Phase shifts

Mid-IR

Refractive index

Gold

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