A lab that fits in your palm

To understand how a lab-on-a-chip works, try this simple experiment at school. Take a glass slide like the one's used with microscopes. Clean it with soap and dry in the air. With a glass marker, draw lines to divide the slide into six parts. Label them from 1 to 6.

Now get some common chemicals you can find at home - vinegar, lemon juice, baking soda solution, and bleaching powder solution. Put a drop of vinegar on block 1 of the slide, lemon juice on block 2 of the slide etc. On block 5 put a drop of distilled water. Leave block 6 empty. Blocks 5 and 6 act as 'negative controls', which means that nothing should happen there during your experiment. Now let the slide dry.

Meanwhile, with your teacher's help, make a solution of phenol red. This is a pH indicator, which changes colour depending on how acidic or basic the solution is. It is yellow in acid solutions (like vinegar or lemon juice) and red in basic solutions (like bleaching powder or baking soda). When the slide has dried, put one drop of phenol red on each block. What colour do you see? Did the 'controls' change colour at all?

Smaller, Faster, Smarter

That's the idea behind a lab-on-a-chip, to be able to do chemistry reactions in miniature. The actual chip used is as small as a computer chip - it would fit on your thumb. Using advanced technology, really tiny droplets of chemicals to be tested are deposited on the chip (This technology is similar to how your printer cartridge works). Special coatings on the chip ensure that the drops stick to the chip. Then the chip can be shipped out to the labs that need it.

Here's a video* explaining how:-

This technology is used when hundreds of tests must be done all at once. One such use is in 'immunoassays' which are used by pathology labs to detect what illness a patient may be having. Another use is for very fast DNA fingerprinting. And a third one is used for detecting what mix of pollutants might be present in drinking water.

You can see that this technology saves money and chemicals by reducing wastage. It is also an eco-friendly way of doing things.

Challenges ahead

There are still a few challenges to be met. Some chemical tests cannot be reduced to the scale of single drops. Also, forces that act on such small scales like surface tension or viscosity can affect the reaction. And because the chips are so small, they need special equipment that can 'read' the tests.

Nevertheless, the idea of lab-on-a-chip is becoming popular everyday. New tests are being devised to replace the ones that cannot be miniaturized. New ways are being found to deal with physical phenomena. And the special equipment required is now more easily available.

Visit your nearest pathology lab, and you can see a lab-on-a-chip in action!

*Video made by University of Tenessee, Knoxville. Sourced from www.YouTube.com.