Science News

A double-sided solution.

Fri, 12th Dec 2008

It might sound like something that belongs on Blue Peter, but scientists this week have unveiled a new gadget to diagnose diseases made from layers of paper and double sided sticky tape.

Cellophane Tape, with dispenserWhat’s innovative about these new devices is that they are extremely cheap, simple and robust, all features that could make a huge difference in poorer countries.

This new invention was the brainchild of Andres Martinez, Scott Phillips, and George Whitesides from Harvard University who published their study this week in the journal PNAS.

Many conditions and diseases can be diagnosed by identifying particular substances in body fluids for example elevated sugar in urine is an indicator that someone has diabetes.

At the moment, the main options available to test for various conditions like this are paper-based dipsticks that work by passing fluid across a flat sheet of paper that has been impregnated with reagents that change colour in the presence of particular molecules. But these tests are limited in their capabilities and the different conditions they are able to test for.

The secret behind these new test plates is their three-dimensional structure. The Harvard research team used a laser to cut patterns in double-sided tape – although apparently the patterns could also be cut using a simple mechanical hole-punch, but that would take a lot longer - and then they built up a 3D structure with layers of tape and paper.

This creates waterproof channels and chambers and by dotting different types of light-sensitive reagent into the chambers, an array of thousands of detection zones can be set up that will test for many different molecules at the same time.

These devices should cost around 2p each to make, and because they draw fluid passively through them using capillary wicking forces there is no need for electric pumps, and no detection equipment is needed either – the test devices simply show the results in different coloured spots. So they really are very simple and straightforward to use.

And a trained healthcare worker doesn’t even have to be present to interpret the results – a new application of technology is to use camera phones to take pictures of these new diagnostic devices and send them to a specialist diagnosis centre.

The sorts of applications we might see for these paper diagnostic kits could be not just for healthcare, but also for environmental monitoring, for things like testing water and air quality.

It’s great to see a simple but ingenious device that could have really important uses for people all around the world.


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