Printing tecnologies for biotechonological and environmental sensing applications.

Student thesis: Doctoral thesis


Modern industrial activities have left wide-spread hazardous pollution in soil, air and water across the globe. Emissions of SOx coming from flue gases require treatment before their release into the environment. Conventional physic-chemical treatments used hitherto are expensive and time-consuming. Moreover, those treatments also generate wastewater that requires further processing. To overcome the SOx treatment challenge, a new approach using environmentally friendly biological method is proposed. The process is based on a selective adsorption of SOx, followed by a two-stage biological treatment. Once the SOx are adsorbed they undergo a first biocatalytic stage, in which sulfate-reducing microorganisms catalyze their conversion into hydrogen sulfide. Afterwards, a second biocatalytic stage by sulfide-oxidizing microorganisms is done, finally obtaining elemental sulfur. A crucial point to address in this biotechnological process is the real-time quantification of sulfur species before and after each biocatalytic stage. Conventional methods, such as gravimetry, turbidimetry, nephelometry, capillary electrophoresis and ionic chromatography have been widely used for sulfur species quantification. Although those methods have been overwhelmingly implemented a few decades ago, they are not suitable of in situ real-time measurements, require trained personnel and they are costly and time consuming. Therefore, there is a need to provide new analytical systems that can replace conventional ones. Microfluidic platforms have been extensively studied due to their possibility of replacing a fully equipped conventional laboratory. Well-known advantages of these microfluidic sensing systems include: compactness, low sample consumption, low-cost production, better overall monitoring and process control, real-time analysis and a fast response. These characteristics open the possibility of performing in situ and real-time measurements. Also, they operate in such a manner that sample pre-treatment as well as chemical assay can be performed therein. Their ergonomic and user-friendly design allows them to be easily adapted to perform a desired analysis just by simply modifying the geometry of the channels. These features make microfluidics of interest in processes that require multiple analyses at the same time. Several microfabrication techniques (e.g., micromachining, hot embossing, injection molding, laser ablation, micromilling and soft lithography) and materials (e.g., silicon, polymers, metals, ceramics, etc.) have been used for the production of miniaturized analytical systems. Nonetheless, all these methods require trained personnel and are expensive and time consuming. Moreover, they require further processing steps (e.g., etching, sealing, etc.) after the fabrication. Nowadays, scientists have been exploring new methodologies to produce such analytical systems in a more feasible and cheaper manner. In this thesis, the use of printing technologies (inkjet printing, screen-printing and 3D printing) to produce analytical platforms for quantification of relevant chemical compounds in biotechnological reactors and in the environment (S2-, SO42- and NO2-) are promoted. Hence, the state-of-the-art of microfluidic devices and the printed analytical systems have been widely developed.
Date of Award23 Jul 2019
Original languageEnglish
SupervisorFrancisco Cespedes Mulero (Director) & Maria Mar Baeza Labat (Director)

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