Reducing the adhesion between surfaces using surface structuring with PS latex particle.

The adhesion between a micro-object and a microgripper end-effector is an important problem in micromanipulation. Canceling or reducing this force is a great challenge. This force is directly linked to the surface chemical structure of the object and the gripper. We propose to reduce the adhesion force by using a self-assembled monolayer structuring on one surface. The surface was structured by polystyrene latex particles (PS particles) with radii from 100 to 1500 nm. The adhesion force measurements obtained by AFM were compared to a multisphere van der Waals force model. The model suggests the existence of an optimal value of the sphere radius which minimizes the adhesion. In that case, the pull-off force is reduced to 20 nN by the PS particles layer with a radius of 45 nm. A wide range of applications in the field of telecommunications, bioengineering, and more generally speaking, MEMS can be envisaged for these substrates.