Analytical Sciences

Development of an Attenuated Total Reflection Based Fiber-Optic Sensor for Real-time Sensing of Biofilm Formation

Tatsuya ORII,* Takuya OKAZAKI,* Noriko HATA,* Kazuharu SUGAWARA,** Faidz A. RAHMAN,*** and Hideki KURAMITZ*

*Department of Environmental Biology and Chemistry, Graduate School of Science and Engineering for Research, University of Toyama, 3190 Gofuku, Toyama 930-8555, Japan
**Maebashi Institute of Technology, Maebashi, Gunma 371-0816, Japan
***Department of Electrical and Electronic Engineering, Lee Kong Chian Faculty of Engineering and Science, Universiti Tunku Abdul Rahman, Jalan Sungai Long, Bandar Sungai Long, Cheras, 43000 Kajang, Selangor, Malaysia

A fiber-optic sensor capable of real-time monitoring of biofilm formation in water was developed. The sensor can be easily fabricated by removing the cladding of a multimode fiber optic to expose the core. The sensing action is based on the penetration of an evanescent wave through a biofilm formed on the surface of the exposed fiber core during total internal reflection. The proposed setup can be used to analyze the transmittance response over a wide wavelength range using a white-light source and a spectroscopy detector. The change in transmittance with respect to the biofilm formation on the fiber core surface was observed. The findings from this study showed that the sensor detection had better sensitivity at near-infrared wavelengths than at visible-light wavelengths. Moreover, the sensitivity of this sensor could be controlled by surface modifications of the core surface through electrostatic interactions, involving a silane coupling layer, polyanions, and polycations. The developed sensor was successfully applied to evaluating of the effectiveness of a commercial biofilm inhibitor.

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