Dongqing Li

Professor, Mechanical and Mechatronics Engineering

Research interests: micro/nano fluidics; lab-on-a-chip; EMK transport

Biography

Professor Dongqing Li obtained his Ph.D. degree at the University of Toronto in 1991. In 1993, Li joined the faculty of the Department of Mechanical Engineering, University of Alberta, where he obtained tenure in 1997 and was promoted to the rank of full professor in 1999.

In that same year he was awarded the McCalla Professorship for research excellence. He later joined the Department of Mechanical and Industrial Engineering, University of Toronto, in 2000 as a tenured full professor. From October 2005 to August 2008, Li was the H. Fort Flowers Chair Professor of Mechanical Engineering at Vanderbilt University.

From September 2008, Li has joined the University of Waterloo. Li’s research is in the area of electrokinetic-based microfluidics and lab-on-a-chip technology. Li has published 324 papers in leading international journals, 10 book chapters and three books.

Education

PhD, Thermodynamics, University of Toronto, 1991
MSc, Heat and Mass Transfer, Dalian Maritime University, 1984
BASc, Thermophysics Engineering, Zhejiang University, 1982

Dongqing Li

Research

Lab-On-Chip (LOC) devices are microscale laboratories on a microchip that can perform clinical diagnoses, scan DNA, run electrophoretic separations, act as microreactors, detect cancer cells and identify bacteria and virus.

The objective of our current research program is to develop quantitative microfluidic technologies that enable the chip-scale design and operation control of pumping, metering, switching, sample injection/dispensing, mixing, reacting, and separating processes. Our research includes developing Enzyme-Linked Immunosorbent Assay (ELISA) chips for detecting bacteria and viruses, DNA sensing chips, real-time Polymerase Chain Reaction (PCR) chip systems, dielectrophoresis cell detection chip, and cellular lab on a chip.

The typical lab on a chip is a thin glass or plastic plate with a network of microchannels etched into its surface. These microchannels are about 10 microns deep, 50 microns wide, and several centimeters in length.

A liquid sample (as little as 100 picoliters) is injected at one end of a microchannel. Electric fields propel the sample along the channels, past reservoir chambers that squirt measured amounts of reactants into the sample as it moves over detectors that scrutinize the progress of the reaction. On such a chip, hundreds of different reactions and analyses can be performed at the same time through hundreds of parallel microchannels. The advantages of these labs on a chip include very small amount of sample, very short reaction and analysis time and high throughput, and portability. These are the medical and technical drivers of next generation, handheld, portable, biodiagnotic devices.

Precise manipulation of liquids and particles in microchannel networks is key to the performance of Lab-on-a-chip. In order to operate, such a lab-on-a-chip device must be able to perform the following microfluidic functions: pumping, metering, switching (flow), dispensing, mixing, and separating.

However, because of the scale of the microchannels, interfacial electrokinetic phenomena dominate the transport processes in the microchannels and make the microchannel transport processes very different from the macroscopic transport processes. At the present, manufacturing a lab-on-a-chip device is not a problem; however, the lack of understanding of the complicated electrokinetic transport phenomena in microchannels makes it difficult to do systematic design and precise operation control of the lab-on-chip devices. That is why most of the lab-on-a-chip technology still stays in the proof-of-the-concept stage. Fundamental research on microfluidic transport processes is therefore required for further development of the lab-on-a-chip technology.