UBC Theses and Dissertations

UBC Theses Logo

UBC Theses and Dissertations

Study of mass transfer and continuous chemical purification in two-dimentional electro-fluid-dynamic devices Liu, Chang


The development of separation science is one of the most important contributions in analytical chemistry, and current separation systems can analyze less than femtomoles of analyte. However, the need for such ultrasensitive technology is partly driven by the difficulties in obtaining appreciable quantities of pure substances. Therefore, a platform enabling the purification of chemicals in a preparative fashion from complex mixtures is required. In this thesis, a new continuous chemical purification platform is introduced, based on the interactions of analyte with multiple types of driving forces in a twodimensional electro-fluid-dynamic (2-D EFD) system, in which both electric field and hydrodynamic pressure are simultaneously utilized in 2-D microfluidic channel networks. Mass conservation is the guiding principle for analyte distribution in channel intersections. However, in EFD devices, the mass distribution is more complex. In order to understand the analytes’ transportation behaviour in multiple force fields, we studied the mass transfer in EFD devices, and discovered the effective volumetric flow rate conservation principle. It can be used to predict the analyte concentration in a channel, and provides a theoretical basis for investigating the mass distribution in EFD devices. Y-shaped microfluidic devices have been extensively used for mixing components. With the strategically applied electric potential and hydrodynamic pressure, such spontaneous mixing process can be reversed in the same device. A continuous solution stream containing a mixture of two analytes can be separated into two channels, each containing a pure compound. By increasing the geometry complexity, more complex samples can be processed. Amultiple-branched device is introduced for continuously purifying multiple analytes. Each component in the introduced mixture can be directed to enter its specific collection channel, without any contamination. In the study of sample injection methods, the hydrodynamic injection is superior to the electrokinetic injection in the purification process by providing faster sample processing and being more resistant to the fluctuating electroosmotic flow. In addition, the buffer depletion problem can be fully resolved. The stringent control and ease of operation of this technique could lead to a new generation of purification devices to serve the needs of academic research and commercial activities.

Item Media

Item Citations and Data


Attribution-NonCommercial 3.0 Unported