Microphotonic sensor for monitoring of water chemistry

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We will develop an integrated, ultra-compact chemical sensor array system that is suitable for ppb to ppm level detection of common contaminants in water. Our main targets are phosphate, nitrate, and ammonium in industrial process water or industrial and municipal wastewater. The project was approved for funding at $80,000 p.a. by ABB in their call for proposals on "Sensors for water analysis". The proposed work uses a newly developed microphotonic silicon chip that has already been multiplexed into 128 parallel optical channels. This sensor platform is coated with rugged and custom-designed films of functionalized mesoporous silica materials, which were patented by the applicants in 2010. In the current application we will develop microphotonic devices as sensors - specifically, silicon-waveguide ring-resonators. Silicon-on-Insulator (SOI) microphotonic devices are fabricated on silicon wafers and are made using similar processes as are employed for electronic integrated circuit microfabrication, which means that their fabrication is amenable to inexpensive scale-up. Our sensor arrays are based on integrated optics technologies, i.e. light guiding, distribution, and sensing are performed on a single chip. Since micro-photonics permits highly parallelized detection on a very compact platform, the sensor array allows for simultaneous and specific quantification of different contaminants from the percent level to the parts-per-billion level. The silicon waveguide chips are fully compatible with silica-based materials, thus providing a greatly enhanced flexibility in the design of the sensing materials. It will be straightforward to prepare a variety of new chemically selective materials to permit detection of specific chemical contaminants. During this project 3 graduate students and 2 postdoctoral fellows will be trained on material synthesis, application of optical coatings, thin film characterization for chemical and optical properties and micro-analytical techniques. Part of the training will take place at ABB's laboratories.