Adhesion and removal of particles from surfaces under humidity controlled air stream

The adhesion and the removal of individual micrometer-sized particles on a plane substrate are studied using an air shear flow cell. Laminar isotherma l compressible flow characterization enables us to analyze the effect of va rious parameters such as particle size, air humidity, surface nature and su rface charge on the aerodynamic forces required to remove the particles fro m the substrate, The results show that the increase of humidity (up to a cr itical value) favors particle removal when particles adhere under strong el ectrostatic forces on a non-conductive charged substrate. On the contrary, the existence of a capillary force disfavors particle removal beyond this c ritical humidity. The increase of the humidity disfavors the removal of par ticles in contact with an uncharged substrate. The results are interpreted in terms of a global adhesion force using a force and torque balance on a s ingle particle in contact with a plane substrate. Moreover, the use of a hi gh-speed video recording system enables us to determine the particle remova l mechanisms as a function of the particle Reynolds number.