As a doctoral student at the University of Toronto, Xinyu Liu developed an innovative microrobotic system that could inject DNA or proteins into individual cells. "It is very difficult to manipulate such tiny objects," says Liu, now Assistant Professor at McGill University, leading the Biomedical Microsystems Laboratory of the Department of Mechanical Engineering.
Many biologists perform this type of injection by hand, using a glass needle. Liu and his colleagues, including his PhD supervisor, Dr. Yu Sun, developed an automatic microinjection system with a distinctive benefit: automating, and thus speeding up the insertion process. "A user can sit in front of a computer screen and click the mouse a few times and the injections are performed automatically. High throughput was one of our goals. The system can perform at a rate of 12 injections a minute, which is five times faster than the manual approach."
He and his collaborators were able to show that their first-of-its-kind automated system had a higher success rate than manual methods. The experiment involved injecting mouse embryos with a mitochondrial protein that helped the embryos survive in a laboratory culture environment. This novel work is now being commercialized.
In addition, he also worked with another researcher from the Toronto group to adapt the system so it can inject human sperm into eggs. The system is able to assist a clinical doctor to perform in vitro fertilization (IVF) with much improved accuracy and consistency. The devices he has developed have made significant contributions to clinical reproductive medicine and garnered him two prestigious awards at major reproductive medicine conferences. The automated method has been tested in a Toronto IVF clinic.
After earning his PhD at the University of Toronto, Dr. Liu accepted a post-doctoral position in the Chemistry Department at Harvard University. There, he extended his research to a new field called paper-based microfluidics. The approach is similar to the "lab-on-a-chip” technologies that involve fabricating tiny channels in silicon or plastic chips. The benefits of microfluidic paper-based analytical devices (µPADs) are primarily that paper is a common and inexpensive substrate that is compatible with many biochemical applications; in addition, paper’s structure can allow fluid movement without the use of external pumps. In his present research, Liu is able to create channels in paper, through which small amounts of fluid, like blood, can be directed to a reaction zone and tested for the presence of viruses, bacteria, or other markers.
Paper-based microfluidic devices have obvious medical applications, but could also be used in environmental monitoring, agriculture and even food industries, for instance, to test water for contaminants or help vintners measure the level of alcohol in wine.
At McGill University, his group is designing new types of paper-based diagnostic devices, which will be tested in Nairobi, Kenya through collaborations with Kenyatta University. The paper-based technology could lead to much cheaper and easier-to-use diagnostic tests – important factors in improving health care globally.
“This research was a major shift in direction. After I left the Toronto group, and did my post-doctoral work at Harvard, I entered this whole new field of research and discovery. Yet there are many connections to my earlier experiences, because developing these microdevices out of paper requires design, simulation, and microsystem testing skills, so a lot of my expertise continues to be beneficial.”
Liu values the helpful support provided by CMC for his research, “I’ve used finite element simulation software for MEMS device design and the fabrication service to produce microdevices for proof-of-concept purposes.” The ultimate goal of his research program is to invent enabling engineering technologies to fundamentally change how biological research is performed and how health care is practised. Liu plans to continue to take advantage of the support available from CMC to support these endeavours, including using simulation software and expensive test equipment on short-term loan.