Cutting Edge: A prefilled, ready-to-use electrophoresis based lab-on-a-chip device for monitoring lithium in blood

Paul Yager

Paul Yager received his A.B. in Biochemistry from Princeton in 1975, and a PhD in Chemistry from the University of Oregon in 1980, specializing in vibrational spectroscopy of biomolecules. After an NRC Fellowship at the Naval Research Laboratory from 1980 to 1982, he joined the NRL staff as a Research Chemist. He joined the Center (now Department) of Bioengineering at the University of Washington as Associate Professor in 1987, advancing to Professor in 1995. Since 1992, Yager has focused on development of microfluidics for the manipulation of biological fluids. The primary goal of current work in the Yager lab is development of point-of-care biomedical diagnostics for the developed and developing worlds.

In the early days there were many justifications for why microfluidic systems would revolutionize analytical chemistry and medical diagnosis. On the basis of the commercial survival of the iStat, some of us thought that the most important applications for microfluidics would be in point-of-care diagnosis. However, the iStat remained alone in its field for many years, and the first commercialized true microfluidic systems were for research, mostly for DNA sequencing and high-throughput screening; it turned out that medical diagnostics was thought to be a “mature field”, and therefore not open to technical innovation. The advances that were made in practical capillary electrophoresis on a chip were substantial, and excellent commercial products emerged, albeit to be used by trained personnel under controlled laboratory conditions. Now, after 15 years of people being trained in microfluidics, the unique advantages of microfluidics for point-of-care devices are more widely recognized, and the business climate for diagnostics has improved as well.

This manuscript by Floris et al.¹ represents the first attempt of which we are aware to produce a single-use disposable CE-on-a-chip device, and one that can be sold at a low cost. There are several technological challenges presented, ranging from the “merely” economic one of making a glass chip inexpensive enough for the end-user, to providing a simple method for loading of the sample, and, perhaps most challenging, to shipping a fully wetted device that would have a decent shelf life. The approach taken by the Medimate team is, at first, startling, in that they chose to create a closed system for CE—with only one port to the outside world for introduction of sample. The standard assumption has been that CE systems had to stay open at the electrodes to vent gases from the device, but instead they have chosen to contain any bubbles generated during a short period of use. Several very clever features have been incorporated that allow this to work, and work reliably with absolutely minimal “fiddling” by the end-user. Also, they have chosen in Li⁺, a first analyte that is both medically important and one that has remained off iStat's analyte list to date. Whether this company proves viable will mostly be up to the vagaries of the marketplace, but the technology demonstrated here shows that, with sufficient clever engineering, even “laboratory” technologies like CE can be made into a viable commercial point-of-care product.

References

1. A. Floris, S. Staal, S. Lenk, E. Staijen, D. Kohlheyer, J. Eijkel and A. van den Berg, Lab Chip, 2010, 10 10.1039/c003899g.

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