Salad spinner centrifuge

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Doctors in developing countries need a cheap centrifuge to test blood samples for anemia. Some university students think they have one. It’s a salad spinner tricked out with test tubes. The students are taking it out for field tests in Ecuador and Swaziland. The World’s Clark Boyd reports.

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This text below is a phonetic transcript of a radio story broadcast by PRI’s THE WORLD. It has been created on deadline by a contractor for PRI. The transcript is included here to facilitate internet searches for audio content. Please report any transcribing errors to theworld@pri.org. This transcript may not be in its final form, and it may be updated. Please be aware that the authoritative record of material distributed by PRI’s THE WORLD is the program audio.

MARCO WERMAN:  Anemia affects millions of people around the world.  It’s caused when the body doesn’t produce enough red blood cells.  It can cause weakness, fatigue and in severe cases, cardiac arrest.  It is particularly problematic in the developing world and it’s not as easy to identify as you might think.  Now a team from Rice University is showing that just about anyone can lend a hand in diagnosing it, literally.  The World’s Clark Boyd reports.

CLARK BOYD:  Rice Professor Rebecca Richards-Kortum works closely with clinicians in the developing world.  She often asks them, how can we help?

REBECCA RICHARDS-KORTUM:  One of the challenges that they presented to us was their inability to monitor whether patients are anemic or not.

BOYD: Diagnosing anemia requires taking a blood sample, separating out red blood cells and then counting them.  That gives you something called the hematocrit, the percentage of red blood cells in a patient’s blood.  To separate the blood cells, you need to spin a small blood sample very fast.  There are battery powered and electrical centrifuges that can do this.  But electricity in the developing world is sometimes hard to find and expensive.  So, last fall, Richards-Kortum put the hematocrit problem to an undergraduate class on Bioengineering and World Health at Rice.

RICHARDS-KORTUM:  The students were tasked with developing an inexpensive way to assess hematocrit levels in a situation where electricity wasn’t available.

LILA KERR:  We just thought to ourselves, you know what is something cheap that doesn’t require electricity that spins?

BOYD: Lila Kerr was one of the students in Richard-Kortum’s class.  She and some of the other students from the class started brainstorming.  They thought about bicycles, different kinds of spinning toys, they experimented with a Harvard project involving the use of an egg beater.  In the end, they didn’t go with the egg beater, but they did stay in the kitchen.  That’s a pump action salad spinner, you know the kind with the hard plastic outer bowl and an inner plastic basket?  You put the lettuce in, close the lid and push the pump on top of the lid to spin the water off.  Lauren Theis was one of the students involved in modifying the spinner to hold small vials of blood.

LAUREN THEIS:  So on the bottom of the basket we built this elevated vial holder, or tube holder using things like a food container and circles of combs so it holds different tubes at a 70 degree angle.  So essentially what we did to modify the device was just create that base to hold the tubes.

BOYD: So how long and how fast do you have to spin it to get it to work as a centrifuge?  Again, Rice student Lila Kerr.

KERR:  The user pumps it for 10 minutes.  You pump it about 200 times per minute, which sounds harder than it actually is.  We pumped it for up to 20 minutes and it really wasn’t too bad.  And then at that rate, it spins it 950 rpm, which is enough to separate the blood.

BOYD: Total cost, around $35.00.  A battery powered, or electrical centrifuge can run into the hundreds of dollars.  Also, the salad spinner centrifuge can hold up to 30 samples.  A portable electrical model holds about four samples.  But the question is, can the salad spinner centrifuge hold up in conditions far more rugged than the kitchen?  Lila Kerr and Lauren Theis will find out this summer.  Kerr is taking one of the centrifuges to Ecuador.  Theis is taking one to Swaziland.

THEIS:  Maybe just getting it there on the plane will be a good indication of how well it will hold up.  But it is very durable.  It’s a really hot powered outer container, so we’re hoping that it’s sustainable and durable enough to really, if it suffers a fall and heat and weather and stuff, it should hold up, but we’re going to find out.

BOYD: The idea is that the students will spend time with clinicians in the field explaining how the device works and getting feedback on its performance.  They will then bring the feedback back to campus next fall and incorporate it into the next design of the centrifuge.  For The World, this is Clark Boyd.

WERMAN: And if you want to see how to turn a salad spinner into a medical centrifuge, visit our website.  There’s really not much to it as the students demonstrating their creation will show you.  The video is at the world dot org.  This is PRI.

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