Title :

Parallel Manipulation of Individual Magnetic Microbeads for Lab-on-a-Chip Applications

Speaker :

Dr. Zhengchun Peng

Postdoc Fellow

Georgia Institute of Technology, USA

Venue :

Room 215, William M. W. Mong Engineering Building, CUHK

Date :

Jan 21, 2011, Friday
11:00 AM - 12:00 PM

Abstract :

Many scientists and engineers are turning to lab-on-a-chip systems for cheaper and high throughput analysis of chemical reactions and biomolecular interactions. In this work, we developed several lab-on-a-chip modules using two different manipulation methods for individual microbeads. The first method employs arrays of soft ferromagnetic patterns fabricated inside a microfluidic channel and subjected to an external rotating magnetic field. We demonstrated that the system can be used to assemble individual beads (1-3繕m) from a flow of suspended beads into a regular array on the chip, hence improving the integrated electrochemical detection of biomolecules bound to the bead surface. In addition, the microbeads can follow the external magnet rotating at very high speeds and simultaneously orbit around individual soft magnets on the chip. We employed this manipulation mode for efficient sample mixing in continuous microflow. Furthermore, we discovered a simple but effective way of transporting the microbeads on-chip in the rotating field. Selective transport of microbeads with different size was also realized, providing a platform for effective sample separation on a chip. The second method integrates magnetic and dielectrophoretic manipulations of the same microbeads. The device combines tapered conducting wires and fingered electrodes to generate desirable magnetic and electric fields, respectively. By externally programming the magnetic attraction and dielectrophoretic repulsion forces, out-of-plane oscillation of the microbeads across the channel height was realized. Furthermore, we demonstrated the tweezing of microbeads in liquid with high spatial resolutions by fine-tuning the net force from magnetic attraction and dielectrophoretic repulsion of the beads. The high-resolution control of the out-of-plane motion of the microbeads has led to the invention of massively parallel biomolecular tweezers.

Biography :

Dr. Zhengchun Peng received a B.S. degree in Automotive Engineering and a B.S. degree in International Business from Beijing Institute of Technology, Beijing in 1998. He worked in industry from 1998 to 2000 in Shanghai. He received a M.S. degree in Mechanical Engineering from Louisiana State University, Baton Rouge, Louisiana in 2002. From 2003-2005, he was a Research Associate at one of the six U.S. synchrotron radiation facilities, Center for Advanced Microstructures and Devices, LA. He received a Ph.D. degree in Mechanical Engineering from Georgia Institute of Technology, Atlanta, Georgia in 2010. He is now a postdoc fellow in Georgia Tech/Emory Joint Department of Biomedical Engineering. His research interest is in the fields of microfluidics and micro/nano electromechanical systems, with focuses on creating functional, efficient components for lab-on-a-chip applications and new analytical tools to study biomolecular interactions and cellular mechanics. His academic background spans from theoretical modeling to experimental research and transferable technologies. He has authored and coauthored more than 10 journal papers and filed three U.S. patterns (provisional).

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Enquiries: Ms. Winnie Wong or Prof. Wen J. Li, Department of Mechanical and Automation Engineering, CUHK at 2609 8337. *MAE Series (2010-11) is contained in the World-Wide Web home page at http://www3.mae.cuhk.edu.hk/maeseminars.php#mae.