This poster presents the measurement of the forces involved in the hydrophobic self assembly process. More precisely the objects of interest are hydrophilic semi spheres with a gold layer on the flat side. The gold layer has been coated with dodeca thiols to make the surface strongly hydrophobic. Due to the low affinityof the water molecules to the hydrophobic sites the latter will assemble together and thus minimize the thermodynamic free energy when near enough. The goal of this experiment was to measure the magnitude and the interaction distance of thiolised surfaces in DI water compared to the hydrophilic surface.