Modification of adhesion between microparticles and engineered silicon surfaces

TL;DR

This paper explores surface engineering techniques on silicon to significantly reduce microparticle adhesion, facilitating better control and levitation of microparticles in experimental setups.

Contribution

It introduces chemical and physical modifications to silicon surfaces that decrease adhesion forces, with quantitative analysis linking surface properties to detachment forces.

Findings

Hydrophobic surfaces reduce microparticle adhesion.

Surface treatments decrease detachment force by over three times.

Quantitative correlation between water contact angle and detachment force.

Abstract

A key challenge in performing experiments with microparticles is controlling their adhesion to substrates. For example, levitation of a microparticle initially resting on a surface requires overcoming the surface adhesion forces to deliver the microparticle into a mechanical potential acting as a trap. By engineering the surface of silicon substrates, we aim to decrease the adhesion force between a metallic microparticle and the silicon surface. To this end, we investigate different methods of surface engineering that are based on chemical, physical, or physio-chemical modifications of the surface of silicon. We give quantitative results on the detachment force, finding a correlation between the water contact angle and the mean detachment force, indicating that hydrophobic surfaces are desired for low microparticle adhesion. We develop surface preparations decreasing the mean detachment force by more than a factor of three compared to an untreated silicon surface. Our results will enable reliable levitation of microparticles and are relevant for experiments requiring low adhesion between microparticles and a surface.