New strategies for (biological) particle handling and separation in microfluidic devices

PhD ceremony: dhr. L.J.C. Jellema, 16.15 uur, Academiegebouw, Broerstraat 5, Groningen

Thesis: New strategies for (biological) particle handling and separation in microfluidic devices

Promotor(s): prof.dr. E.M.J. Verpoorte

Faculty: Mathematics and Natural Sciences

Contact: Laurens-Jan Jellema, tel. 06-21532207

The trend in life science research to miniaturize analytical processes using lab-on-a-chip technology is on-going. However, there are few particle manipulation strategies for analytical and sample pretreatment applications in these chips. The research of Laurens-Jan Jellema describes a new microfluidic system based on a trapping phenomenon for capturing and manipulating particles virtually, without physical barriers, in narrow channels that expand at both ends.

The trapping phenomenon consists of a hydrodynamic effect, which is the result of opposing a pressure-driven flow (PF) with electro-osmotic flow (EOF, fluid flow due to an electric field applied to the fluid in the channel), and the electrokinetic mobility of the particles themselves.

Jellema has shown that a mixture of micrometer-sized polymer particles located in the narrow channel can be separated according to two different properties. Firstly, same-sized particles can be separated based on charge differences. In this separation mode, one type of particle is trapped according to its charge, while particles with higher or lower charges (electrokinetic mobilities) are flushed away with the PF or EOF components, respectively. Secondly, particles with the same charge can be separated based on size differences by the hydrodynamic effect.

Furthermore, Jellema has shown that the technique of particle trapping can also be applied to biological particles like yeast, red blood cells and DNA. He thus anticipates that his technique will be applicable to the preconcentration, pretreatment and separation of various kinds of particles, in biochemical analysis, environmental studies or in industrial or medical environments.