Nowadays, chemistry plays an important role at the interface between organic or inorganic substrates and chemical or biological environment to develop hybrid micro- and nanosystems. Thus, there is a great need to chemically tune the properties of a material into a function such as sample conditioning, separation, recognition and detection of species. Since 15 years, we are continuously developing a chemistry “tool box”, which is focused on the creation of a chemical interface and designed for integrated systems by taking into account the fabrication and applications constraints.[1]

Recently, we have developed low environmental impact processes using molecular vapor deposition of silane for localized biofunctionalization of chemically modified nanopores for label-free detection.[2] The molecular vapor deposition displays several environmental advantages including the prevention of wastes, the requirement of less energy, while avoiding the handling of chemical products and minimizing the potential for chemical accidents. But, MVD process implies the vaporization of the organic molecules restricting the applications. Thus, the deposition of poorly vaporizable or temperature sensitive molecules is problematic. Therefore, we have studied the deposition of molecules on supercritical carbon dioxide (scCO₂) for its remarkable properties: density close to solvents, zero surface tension, low viscosity and high diffusivity. ScCO₂ easily diffuses into porous materials and micro- and nanostructured devices. Due to its low price, its non-toxicity and its non-flammability, this solvent is very attractive for the production of microdevices and their surface treatment. We have demonstrated, for the first time, the deposition of 3,4-epoxybutyltrimethoxysilane on silicon oxide using scCO₂ deposition.[3] This functional scaffold opens new possibilities, such as supported and recoverable catalysts in collaboration with Biosciences and Biotechnology Institute of Grenoble (BIG).

These different approaches allowed us to cover a very large set of applications such as environment,[4] wellness, medicine,[5] energy, microelectronics.[6] In 2016, LETI provides antibacterial hydrophobic materials to CNES for the MATISS project which investigates the antibacterial properties of materials in space to see if future spacecraft could be made easier to clean.[7] The experiment aims to understand the mechanisms of attachment of biofilms in microgravity conditions and was conducted by ESA astronaut Thomas Pesquet in the International Space Station.

Our chemistry “tool box” is thus expanding towards greener processes and broader applications. We are developing innovative solutions for plastic (PMMA, polyethylene, cyclic olefin copolymer…) and biomaterials (nanocellulose…) surface functionalization that will be compatible with high-throughput production methods (e.g. roll-to-roll technic) while providing new properties (antifouling or antibiotic) or smart coatings (stimuli-responsive, self-assembling…).