Microfluidic electrocapture is a powerful method for pretreatment of samples for analysis by mass spectrometry and capillary electrophoresis. The main application is in analysis of proteins, where sample complexity and small amounts offer significant challenges. The device can capture ionic peptides and macromolecules while allowing non-charged species and small ions to pass through. Original sample volumes of around 5 μl can be concentrated into several nanoliters, and limits of detection around 10 fmol have been achieved for a number of proteins. However, the lack of a sufficient basic understanding of the complex interplay between microfluidic flow, diffusion, migration and chemical reactions is an important obstacle for further development of the technology, which now has to proceed  largely through trial and error. Among the most important issues are how to increase the throughput while avoiding excessive heating and bubble formation, and how to improve the separation and capture efficiencies by proper cell design, running conditions and choice of electrolyte.

The proposed thesis project is about studying the mechanisms behind the microfluidic electrocapture, using mathematical model simulations. A basic model has already been formulated in a previous project, and some simulations have been run using the Comsol Multiphysics software package. The model simulations however need further improvement in order to make it a useful tool for studying the electrocapture process. The aim on a longer perspective is to identify the subprocesses and design features that are the most critical to its proper functioning and to contribute to its further refinement as well as expansion to new applications.

Contact: Mårten Behm, T: +4687908078, E-mail: behm@kth.se