Tiny medical advances

It’s no exaggeration to say that semiconductors have revolutionized every facet of life in industrialized nations. One of the latest results of the silicon transformation is the emergence of “Lab on a Chip” (LOC) technology. LOC systems give doctors and medical professionals quick, precise results and streamline the medical process. However, the ability to do complex medical tests on a tiny integrated circuit comes at a prohibitively high price. Developing nations, ones that would arguably benefit most from the compact testing solutions, are also the ones least able to afford such devices.

Currently, LOC technology allows for a small integrated circuit (IC) to process various laboratory tests — tests that detect the presence of a virus or a cancer, for example. The LOC systems use a minimal amount of reagents and test materials, often measured in picoliters (one picoliter is equivalent to one trillionth of a litre), thereby decreasing laboratory chemical costs and making the procedures less invasive and quicker.

Just how quick? A new device designed by a team of Vancouver-based scientists is able to separate human DNA from virus DNA almost instantly. Called a “tricorder,” in honour of the multi-purpose medical device of Star Trek fame, the battery-powered device is aimed at doctors attempting to diagnose patients with non-specific virus symptoms. Andre Marziali and his colleague, Lorne Whitehead, who run the project, explain their motivation: “If a patient comes in with a sore throat, fever or cough, there’s a good likelihood it’s influenza. But we don’t know if it’s influenza A, or influenza B, or if it’s one of the [other] viruses circulating. These different kinds of viruses are closely related to each other.”

With lab tests taking at least five days to process, the patient is usually diagnosed much later — with only a 70 per cent success rate, writes the Vancouver Sun.

With the tricorder, a faster and more accurate diagnosis can be made. “The device will have various ways of taking samples from patients — such as blood tests or throat swabs” and will remain inexpensive, according to the scientists behind the project. The device will require disposable cartridges, so the group’s goal is to keep the overall cost low. The tricorder is set to hit markets within three years — that is if the group receives appropriate funding.

Currently, most LOC devices, including the tricorder, depend on tiny “microfluidic” circuits. Although they allow for a targeted and minimal use of testing chemicals, microscopic fluid systems are both expensive and difficult to engineer.

A group of scientists from Purdue University aim to change that, and hope to bring LOC devices to the poor and those in developing nations. Using a technique involving a laser and common wax paper, they were able to burn microfluidic channels into the paper substrate. The technique is straightforward, easily repeated and uses very inexpensive off-the-shelf materials.

The technique, according to purdue.edu, attempts to “enhance commercially available diagnostic devices that use paper-strip assays like those that test for diabetes and pregnancy.” Instead of difficult to manufacture, single-function chips, the scientists aim to create a system where a single sheet of paper could be used to do multiple tests.

To create the microfluidic channels: “A laser is used to burn off the hydrophobic coatings in lines, dots and patterns, exposing the underlying water-absorbing paper only where the patterns are formed,” writes purdue.edu. Then, “the strips might be treated with chemicals that cause color changes when exposed to a liquid sample, with different portions of the pattern revealing specific details about the content of the sample. One strip could be used to conduct dozens of tests.” Afterwards, it would be a matter of inserting the strip into an electronic reader, akin to commercially available glucose testers.

These systems may be the future of medical testing, allowing for quick and decentralized tests to be run in areas without expansive medical infrastructure. The speed and precision will allow for quicker and more directed responses to epidemics, as well as improving the disease-treatment matches for patients.