Recent advances in microbiology and force measurement techniques allow to perform quantitative mechanical experiments on single biomolecules. In this project, I will investigate the elementary processes of adhesion, at the level of a single molecule of DNA. I envisage a series of quantitative force measurements under conditions controlled to the molecular level. A typical experimental configuration will consist of a single DNA molecule attached by one end to a solid surface and by the other end to a microscopic bead. The latter is fixed to a soft micro-needle and forces are directly measured by a microscopic imaging of the bead. I will study the interaction between the molecule and a solid surface as well as some specific interactions within the biomolecule itself. The experiments, which will be prepared in close collaboration with biologists, are interesting from a physical, biological and applied point of view.