Sol-gel processes applied to micro- and nanotechnology

In this thesis, we intend to develop the sol-gel technology (a chemical way to make glass) from the traditional "raw" materials side to a novel technology allowing realization of innovative products in the field of micro- and nanotechnology. We first present the development of a process for the realization of 60 µm thick and 100 µm wide microlens arrays in sol-gel glass, based on an innovative photoresist replication and softening method. We synthesize and characterize our hybrid organic/inorganic sol-gel glass solution. The structural and optical characterizations indicate the reproducibility and high optical quality of our sol-gel glass micro-lens arrays. Then, we demonstrated a novel non-aqueous synthesis route to obtain a borosilicate solution used for the in situ modification of a poly dimethylsiloxane (PDMS) microchannel. Our modification process is producing a covalently bonded smooth and sub-micron thick (800 nm) crack-free borosilicate glass coating. The efficiency of the coating is demonstrated by a negligible diffusion of fluorescent Rhodamine B in the PDMS, when flowing water- and toluene-based solutions through the microchannel. Moreover, the coating prevents swelling and consequent structural damage of the PDMS when exposed to harsh chemicals like toluene. Finally, we discovered and report on an original process for the generation of borosilicate nanoparticles by mixing a non-aqueous Si-B binary oxide solution with water. Our experiments allow us to assess the borosilicate nature of the generated particles, and also to propose a novel formation mechanism via exothermic phase separation. Our discovery has high potential; not only for life science applications, but monodisperse borosilicate particles could be key to the realization of photonic bandgap devices with high optical contrast, contrast agents for ultrasonic microscopy or chemical filtration membranes. To sum up, our work demonstrates the possibility of innovative and versatile use of the sol-gel process in the micro- and nanotechnology field.