Experimental implementation and optimization of EFGF in microfluidic chips

Electric field gradient focusing (EFGF) is a protein separation technique which separates and up-concentrates proteins by applying a force balance on the analytes. This force balance consists of a hydrodynamic force, applied by a flow; and an electric force, applied by a gradient electric field. By this force balance, the analytes will be electro-captured at a location depending on their intrinsic properties. Whereas most separation techniques suffer from time-dependent peak-broadening by molecular diffusion, this technique offers the unique advantage of counteracting this dispersion by the force balance. Hence, EFGF can deliver tightly focused analytes, resulting in high resolution separations. By implementing this technique in microfluidic chips, small samples can be analyzed with high precision.

Implementing those two forces in a microfluidic chip imposes several practical challenges. E.g. generating an electric field in an aqueous buffer is often accompanied by hydrolysis, generating gas bubbles at the electrode’s surface. To block those gas bubbles from entering the fluidic separation channel, a semi-permeable membrane will have to be included in the device. Furthermore, the presence of the electric field could result in an unwanted DC electro-osmotic flow in the channel, which is known to distort the flow in EFGF devices, and to cause unwanted peak-broadening. This must be suppressed, by e.g. a surface coating.

During the thesis, these challenges will be addressed experimentally. By fabricating simple proof-of-concept devices, the student will propose several practical solutions and contributions towards a final working device. The devices will be tested with several proteins, to prove the compatibility of the proposed solutions towards protein analysis systems. We are looking for a student doing a master’s program in nanoscience, nanotechnology or in bioscience engineering, who has interest in the field of protein analysis, microfluidic devices and electrochemistry. The thesis work will be mainly experimental, therefore we are looking for a student who can work independently in a lab environment.

The work will consist of 10% literature search, 10% modelling, 60% experiments and 20% reporting.