Luminescent ru(ii) dyes and materials for gan-based gas microsensors

Resumen

This thesis presents the research carried out as part of the EU Marie Skłodowska-Curie Innovative Training Network “SAMOSS” (Sample In-Answer Out Optochemical Sensing Systems), involving other 9 early stage researchers at PhD programs in 5 universities (Univ. Complutense de Madrid, Univ. of Applied Sciences of Jena, Ben-Gurion Univ. of the Negev, Austrian Inst. of Technology, Univ. of Groningen, Univ. of Technology of Compiègne) plus two experienced researchers working at two companies (Micronit Micro Technologies B.V. in Enschede, NL, and Biosensor S.r.l. in Rome, IT). This work has been carried out in the laboratories of the “GSOLFA” (Chemical Optosensors and Applied Photochemistry) group at the Organic Chemistry Department of Universidad Complutense de Madrid (UCM), at the ISOM (Instituto de Sistemas Optoelectrónicos y Microtecnología) of the School of Telecommunications Engineering of Universidad Politécnica de Madrid (UPM) and, in a four-month long secondment in The Netherlands, in RUG (University of Groningen) and in Micronit Micro Technologies B.V. The aim of this project has been to develop sensitive elements that, with the proper miniaturized large-scale integration electronics, could be plugged to provide smartphones the capability for detecting chemical species of interest for personal and workplace safety (e.g. ethanol and oxygen). The sensitive elements have been organic‐inorganic hybrids fabricated either by direct functionalization of GaN or by attachment of a thin dyed polymer layer to the surface of the GaN LED. Some basic issues regarding selection of proper luminescent dyes and optimum doping of GaN, in order to understand and control the electron transport from the dye to the GaN device, have been addressed as well. Besides, complementary applications of the sensor devices have been explored. The thesis is organized as follows: I. INTRODUCTION. The state-of-the art, motivation for the work, main goals and work plan are explained. II. GaN-SILANE-DYE HYBRID MATERIALS FOR LUMINESCENT CHEMICAL SENSING. The third part reports the manufacturing of GaN‐based organic‐inorganic hybrids for O2 sensing, with an emphasis on the optimization of the sensitive element material. The O2‐sensitive dye has been tethered to GaN surfaces via an aminosilane-coupling layer for utmost stability and durability. The main interest has been to study 1) the influence of the GaN substrate doping and 2) the effect of the intermediate layer composition and thickness on the hybrids luminescence and response to the analyte (O2). III. DEVELOPING AN OPTODE FOR EtOH SENSING BASED ON Ru(II) INDICATOR DYES. This section focuses on the preparation of novel luminescent indicator dyes and indicator/polymer layers for ethanol sensing. The work started with computer‐aided design, followed by chemical synthesis and characterization of the dyes. Subsequently, the best luminescent probe has been supported in perm‐selective polymers and calibrated in gas phase with different concentrations of EtOH and H2O to investigate selectivity and analytical features, focusing on the specific application of monitoring ethanol production and storage plants. IV. APPLICATION OF LUMINESCENCE-BASED MICROSENSORS TO MICROFLUIDIC CELL CULTURES AND ORGAN-ON-A-CHIP DEVICES. Finally, the work focused on a particular application of the developed sensors, namely to monitor microfluidic cell cultures. In RUG, O2 sensors have been implemented in human umbilical vein endothelial cells culture into PDMS-glass microfluidic chips while, at Micronit, O2 and temperature sensors have been used in organ-on-a-chip glass devices. V. HIGHLIGHTS, CONCLUSIONS, AND OUTLOOK.   The three main chapters contain material that has already been published. They were adapted to the thesis format but written as independent chapters with a short introduction and conclusion.