Surface water used for drinking water production is frequently monitored in The Netherlands using whole organism biomonitors, with for example Daphnia magna or Dreissena mussels, which respond to changes in the water quality. However, not all human-relevant toxic compounds can be detected by these biomonitors. Therefore, a new on-line biosensor has been developed, containing immobilized genetically modified bacteria, which respond to genotoxicity in the water by emitting luminescence. The performance of this sensor was tested under laboratory conditions, as well as under field conditions at a monitoring station along the river Meuse in The Netherlands. The sensor was robust and easy to clean, with inert materials, temperature control and nutrient feed for the reporter organisms. The bacteria were immobilized in sol-gel on either an optical fiber or a glass slide and then continuously exposed to water. Since the glass slide was more sensitive and robust, only this setup was used in the field. The sensor responded to spikes of genotoxic compounds in the water with a minimal detectable concentration of 0.01 mg/L mitomycin C in the laboratory and 0.1 mg/L mitomycin C in the field. With further optimization, which should include a reduction in daily maintenance, the sensor has the potential to become a useful addition to the currently available biomonitors.

Measuring resonant wavelengths of different modes of a luminescent semiconductor photonic crystal cavity placed on the tip of an optical fiber is proposed and demonstrated for simultaneous measurement of multiple parameters, and is applied to the measurement of temperature and refractive index in the temperature range of 77-370 K. The operation principle is supported by Finite Element Method simulations. The robustness of a simple mounting scheme without adhesives is proven experimentally. The simplicity, extremely small size, and high sensitivity to both refractive index and temperature makes this concept an ideal fiber-optic sensor for a multitude of applications.Index Terms-Optical fiber sensors, Photoluminescence, Photonic Crystals, III-V Semiconductor Materials. 0733-8724 (c)

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