Repulsive Force for Micro- and Nano-Non-Contact Manipulation

International audienceNon-contact positioning of micro-objects using electric fields hasbeen widely explored, based on several physical principles such aselectrophoresis, dielectrophoresis (DEP) or opticaldielectrophoresis (ODEP), in which the actuation force is inducedby an electric charge or an electric dipole placed in an electricfield. In this paper, we introduce a new way to control charges innon-contact positioning of micro-objects using chemicalfunctionalization (3-aminopropyl)triethoxysilane - APTES) able tolocalize charges on a substrate and/or on a micro-object. Wedemonstrate that this functionalization in a liquid with a lowionic strength is able to concentrate a significant amount ofelectric charges on surfaces generating an electric field over along distance (about 10 microns), also call a large exclusion zone(EZ). A model is proposed and validated with electrostatic forcemeasurements between substrate and microparticles (diameter up to40µm). We demonstrate that the magnitude of the force and the forcerange decrease rapidly when the ionic strength of the mediumincreases. Based on the proposed model, we show that this new wayto localize charges on micro-objects may be used for non-contactpositioning