Boosting Polymer Microfluidic Chip Production

We may see medical and environmental diagnostics on plastic chips the size of flash cards in the near future. In a story for MIT News, Jennifer Chu reports on how microfluidic technology, which is also known as lab-on-a-chip technology, could be used to shrink analytical power into a handheld device so that analyses can be done away from laboratories and at the site of sample collection, say, at a doctor’s office or in a chemical-contaminated wheat field.

Microfluidic technology has been in development over two decades now and holds promise to deliver instruments that are small and cheap, and require little sample and reagents to get the work done. But the technology hasn’t quite left the laboratory setting for the real world.

The scenario, however, may soon change, thanks to some research being done at the Massachusetts Institute of Technology  (MIT). As the Chu reports:

MIT’s David Hardt is working to move microfluidics from the lab to the factory. Hardt heads the Center for Polymer Microfabrication — a multidisciplinary research group funded by the Singapore-MIT Alliance — which is designing manufacturing processes for microfluidics from the ground up. The group is analyzing the behavior of polymers under factory conditions, building new tools and machines to make polymer-based chips at production levels, and designing quality-control processes to check a chip’s integrity at submicron scales — all while minimizing the cost of manufacturing.

One reason why microfluidics hasn’t had an easy way out of the laboratory is that many research groups and startup companies in the field have relied on techniques found in the semiconductor industry. The Chu quotes Hardt as saying that semiconductor technology is expensive. The semiconductor industry was never designed to work on soft, pliant polymer-based materials — it was built to work with silicon and similar materials.

So Hardt's group has been designing less expensive equipment specifically designed to work with polymers, such as poly(methyl methacrylate). They have also been developing quality-control methods. Because microfluidic chips have tiny features on the microscale that are invisible to the naked eye, they need to be checked with microscopes, a time-consuming step.

To avoid this step, Chu says:

Hardt and his colleagues came up with a fast and reliable way to gauge the ‘health’ of a chip’s production process. Instead of checking whether every channel on a chip has been embossed, the group added an extra feature — a tiny X — to the chip pattern. They designed the feature to be more difficult to emboss than the rest of the chip. Hardt says how sharply the X is stamped is a good indication of whether the rest of the chip has been rendered accurately.

Hardt’s group aims to change how the manufacturing of polymer microfluidic chips are done so that the introduction of the technology into the marketplace can be accelerated. The Chu quotes Holger Becker, co-founder of microfluid chip shop, a microfluidic production company in Germany:

‘Most of the academic work in microfluidics concentrates on applications, and unfortunately only very few concentrate on the actual manufacturing technologies suited for industrialization,’ Becker says. ‘David Hardt’s team takes a very holistic approach looking into all different process steps and the complete manufacturing process instead of individual technologies.’