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Surface treatments...

The key idea of our research is that minute compositional changes can drastically modify the energetics and dynamics of interfaces without substantially modifying their bulk properties.
Interface science can therefore be a very efficient and economically competitive way of optimising materials, in areas such as microfluidics, where surface effects dominate.

We have developed techniques to provide surfaces on demand by :

   • applying external fields (electrowetting)
   • micro-lithographic masking
   • using surfactants
   • changing the topology of the surface
   • controlling the roughness of the surface
   • grafting molecules
   • dip coating
   • layer deposition
   • micro-contact printing…

Among our successes in this area, we can highlight :

Biotechnology

The project BIA-ATR involves three Universities :  UCL, ULB and UMH.  Its ambitious objective is to develop high-performance general-purpose sensors, which use surface-functionalized optical elements (crystals of germanium, silicon, etc.) to detect receiver-ligand interaction and quantitatively measure the concentration of bound biological mole-cules.  The precision so far achieved for specific examples, is of the order of pico-moles.  Patents have been applied for and a new company, S.A. Biosentech, has been spun off.  Already, unique biochips based on this new technology are being developed.

Superhydrophobic, anti-sticking, anti-icing, … surfaces

The surfaces of lotus leaves are well known to repel water droplets.  They have superhydrophobic surfaces, which we can mimic in the lab with polymers after appropriate and very cheap surface treatments.  This is illustrated in the left figure where we see a tiny water droplet with very high contact angles ~170°. Variants of such surfaces reveal interesting properties such as anti-sticking, anti-icing,  anti-mud, …

Smart surfaces

Who doesn’t dream of a material whose properties can be changed at the press of a button? Thus, a glass window could become transparent or opaque at will ; clothing could change colour according to the illumination of the sun ; the thermal protection of impermeable cloth could change according to the outside temperature...  It is this type of problem in which we are interested.  For example, we have designed a new very thin polymeric film containing liquid crystal microdroplets whose optical properties can be manipulated by applying a small voltage. A patent has been applied for.

Lubrication

We have helped a private company to design new type of lubricants to transport bottles on moving carriers. We have adapted our measurement techniques to their environment and we have designed for them an ‘ad-hoc’ tool to characterize effectively their products. They are now using this tool routinely to control the products.