Diagnosis in the medical profession is complex, but sometimes the delays in finding a medical problem are caused by mundane processes, such as physically transporting a sample to a specialised laboratory.
According to researchers at Purdue University in the US, in a few years time, the delays could be a thing of the past. They have designed and patented a way of taking laboratory instruments and shrinking them by up to a million times and placing them on a chip.
The ‘mini-labs’ can be used to chemically separate mixtures into pure components. Called capillary chromatography capillary electrophoresis, these separations are used in the analysis of blood and tissue samples.
In standard chromatography, a solution to be separated is poured through a tube packed with various particles coated with a chemical compound. The different components of the solution are attracted to the particles with different affinity. As the mixture flows through the tube, it separates into a series of zones, each containing a pure substance.
The mini-laboratories use the same principle. The difference is in their size and the way they are made. Channels and microscopic ‘particles’ are created using photolithography and chemical etching. The entire laboratory – with chemical reaction vessels the size of a speck of dust and chromatography columns the size of a human hair – is cut from a single piece of silicon. Liquids are moved on the chip by voltage applied at the ends of the channels.
According to the researchers, what makes this device unique is the ability to create tiny, rectangular ‘particles’ within the channels. These monolithic structures, etched into the column as a single unit, serve the same purpose as the packing materials used in conventional chromatography columns and they allow the minilab to perform more complex procedures.
They also contain no moving parts, making them simpler and cheaper to produce. In microfabrication, it is just as easy to create a large number of laboratories as it is to create just one because they are all etched into the silicon chip as a single unit.
The new technology may be particularly useful in pharmaceutical laboratories where scientists analyse thousands of compounds in search of new drug candidates.
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