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Einstein's Tea Leaves -

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Einstein's tea leaves

Reporter: Dr Maryanne Demasi

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19 July 2007

Many have indulged in a good old fashioned cup of tea, but few would've noticed that stirring their
tea leaves would cause them to settle down at the centre of their cup. But according to basic
physics, the centrifugal force cause by stirring your tea should for the leaves to the edges of the
cup - So how do we explain this?

Well, it took the brilliant mind of Albert Einstein to propose a theory which has led to the
development of technology for a new medical test kit which could revolutionise blood testing.


Dr Maryanne Demasi: According to basic physics, when you stir you're your cup of tea, the tea
leaves should be forced to the outside edges of the cup, by centrifugal force.

But Albert Einstein had a theory as to why this isn't so.... And it could have some important medical

Einstein explained that stirring a cup of tea establishes two forces.First, the tea leaves are
pushed outwards by centrifugal force.But then, friction at the base of the cup creates an opposing
force, which pushes the tea leaves towards the centre.

Now you may think so what! But this theory has caused a stir with one Melbourne engineer. Dr Leslie
Yeo has used Einstein's theory to develop technology for a new type of medical test kit.

Dr Leslie Yeo: We're trying to develop a device that can be used to measure your blood cholesterol
or glucose or immuno-deficiencies. Currently, blood testing requires a large sample from the
patient and it takes days for results. A large centrifuge like this one is used to separate the
blood cells from plasma.

Narration:But Leslie's technology does this with only a microscopic amount of blood in less time
than it takes to brew a cuppa!

Dr Leslie Yeo: Here's the micro-device that we use.

Dr Maryanne Demasi: It's a small device isn't it?

Dr Leslie Yeo: That's right. Once the blood goes in there, we put a tiny needle close to it and
turn on the electric field. Its going to create an air flow away from the needle that actually
pushes the liquid around in the micro chamber.

Dr Maryanne Demasi: So the blood actually swirls around?

Dr Leslie Yeo: That's right.

Narration: This reaction happens within seconds. But Leslie's computer shows, in slow motion, how
red blood cells become separated from plasma.

Dr Leslie Yeo: This is what you would actually see down the microscope, these red blood cells would
spiral all the way down the bottom.

Dr Maryanne Demasi: What 'forces' cause the blood cells to gravitate towards the centre?

Dr Leslie Yeo: Well, its a combination of the air flow at the top and a stationary base which
exerts friction on the bottom layer of the liquid and the combination of that will actually funnels
the red blood cells down like a whirlpool and they collect at the bottom stagnation point.

Dr Maryanne Demasi: So that's just like the tea cup with the tea leaves.

Dr Leslie Yeo: Exactly.

Dr Maryanne Demasi: The next step is to incorporate this technology into a portable device - no
larger than a credit card - which can be used to test blood anytime, anywhere.

Dr Leslie Yeo: The people who would benefit most would be the little kids for example who hate
taking blood samples , and people who have regular blood tests and you could do it really quickly
without having to go to the doctors office and you could do it really cheaply as well.

Narration: Leslie predicts it'll take 5 to 10 years before Einstein's theory revolutionises blood
testing, so until then, sit back and enjoy your cuppa.