This thin paper platform, which can be produced by a standard desktop printer, does the work of a hospital disease diagnostic laboratory.

This thin paper platform, which can be produced by a standard desktop printer, does the work of a hospital disease diagnostic laboratory. Photo by: Ryan Fobel

With a population almost three times that of Canada’s, Vietnam has just two hospitals capable of confirming the presence of measles or rubella in a patient’s body. In places where that diagnosis cannot be made, doctors often present hard choices to patients suspected of having these diseases, which can wreak havoc on the health of unborn children. Expectant mothers can be forced to consider the prospect of abortion without certain knowledge that they may — or may not — be infected with rubella or measles.

Alphonsus Ng and his colleagues at the University of Toronto’s Institute of Biomaterials and Biomedical Engineering are attempting to solve this difficulty by equipping hospitals in outlying regions with a diagnostic platform that uses a drop of blood on a slip of paper the size of a movie ticket. If that sounds too simple, consider the fact that these paper-based assays are being cranked out on the same cheap ink-jet printers you could buy from any department store. “We are a liquid handling lab,” says Ng. As a postdoctoral fellow in the Microfluidics Laboratory of chemistry professor Aaron Wheeler at U of T, Ng has been working on this approach for several years. “We miniaturize big laboratory equipment into credit-card size devices that can deliver the same performance with smaller sample sizes,” he says. 

Ng distinguishes these devices from microfluidic templates that employ etching techniques borrowed from computer chip manufacturers. In this case, droplets move across an open paper surface that has no physical channels, guided instead by electric fields generated by an array of electrodes. “We are able to move droplets on the order of microlitres on this checkerboard where we have arrays of these electrodes,” says Ng. “When I turn on an electrode, I’m able to make a droplet move toward it. In that way, we’re able to do very complicated sample processing with liquids like immunoassay reagents and blood samples.” 

This open surface method avoids the channel clogging that can plague microfluidics arrays when samples or reagents consist of solids or particles. Even more importantly, the cost should be much lower. “By making it on paper it’s much cheaper,” he says. “We can potentially make devices for less than a dollar each.” 

Ng is looking forward to putting that claim to the test in the coming months, now that the research team has received a $112,000 award from Grand Challenge Canada, a federal program that promotes the commercialization of innovations. The device is now being adapted from its laboratory setting into a version that could operate independently in a field setting, so that Ng and others can test it at some smaller hospitals in Vietnam. “We want to be able to test it on some real patient samples,” he says. “Now we’re in a position to use this technology in a developing country where the infrastructure is not as good, so they can figure out who is infected and therefore limit outbreaks.”