Selectivity of the separation of semiconducting and coated particles using inhomogeneous alternating fields

• Applicant: Dr.-Ing. Laura Weirauch
• Subject Area: Mechanical Process Engineering
• Term: since 2026
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 579999905

The purification and sorting of nano- and microparticles is a topic of great importance for industry. Particle systems with specific properties are essential for numerous high-tech products, such as photovoltaic cells, energy storage components, sensors and microelectronics. Conventional separation processes often reach their limits in the lower micrometer range, are less efficient or are not sustainable. The separation of particles with almost identical size and shape but different electrical properties is particularly challenging. A mechanical separation technique, valued in bioanalysis for its high selectivity, is based on the dielectrophoretic force. Dielectrophoresis (DEP) is the movement of polarizable particles in an inhomogeneous electric field. DEP can be used to selectively retain particles in the nanometer and micrometer size range on the surfaces of electrodes or filter media. Separation processes based on DEP are therefore non-invasive and particles can be manipulated without changing their properties. This offers great potential for sustainable processes, as the separated particles can be reused directly and the use of problematic chemicals is not necessary. A distinctive feature is that the DEP force can be controlled both in its strength and in its direction by adjusting the amplitude and frequency of the electric field. This means that the process can be adapted to different particle systems and different particle properties such as size, material or shape can be addressed and selectively separated from one another. DEP separation processes are primarily implemented in microfluidic setups and the focus of research is mainly in the (bio)medical field. Due to this focus, there is little knowledge about polarization and the separation of technically relevant particles. The aim of the project is to provide the basis for the separation of particle systems containing semiconductor materials or (heterogeneously) coated particles. The separation of such particles using inhomogeneous electric fields has hardly been researched so far and separations could at best be realized on a microfluidic scale. The project combines experimental work and theoretical modelling to investigate the fundamentals of polarization of semiconducting and coated microparticles in inhomogeneous electric fields. The knowledge gained will be used to design high-throughput DEP separation setups and extend them to technically relevant particle systems. The results of this project should demonstrate the potential of this technology for industrial applications and can provide innovative approaches for sustainable alternatives to conventional separation and recycling processes.

• DFG Programme: Research Grants