美国国家公共电台 NPR How A Cheap Magnet Might Help Detect Malaria（在线收听）

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Each year, malaria kills about half a million people around the world. Health officials say a fast, cheap, accurate way to test for malarial infection would be extremely helpful in combating the disease. As NPR science correspondent Joe Palca reports, some engineers in California say they have invented a device they hope will do just that.

JOE PALCA, BYLINE: A few years ago, Andrea Armani heard a lecture from officials at the World Health Organization about the need for better tools for detecting the malaria parasite in people's blood. Armani is a professor of engineering and material science at the University of Southern California. She says the lecture resulted in a kind of epiphany.

ANDREA ARMANI: I lead a research group with a lot of really smart students. And if I directed all their energy in a concerted effort, we could actually change the world.

PALCA: So that's what she decided to do. Even though she had no experience with malaria, she decided to build a parasite detector. Her graduate student Samantha McBirney was completely on board with a project aimed at changing the world.

SAMANTHA MCBIRNEY: I've never really envisioned myself being the type of engineer who works on developing the iPhone 23 or works on creating new face filters for Snapchat.

PALCA: So McBirney and Armani started working on their detector. McBirney says they had one overarching goal for their device.

MCBIRNEY: Keeping it as stripped and inexpensive and easy to use as possible.

PALCA: The device is basically a box about the size of a toaster oven. Inside are a laser and a magnet. Andrea Armani says it's not a fancy laser.

ARMANI: It has about the same amount of power as a laser pointer.

PALCA: The magnet is small and cheap, too. But the magnet is key because it turns out that the malaria parasite produces tiny magnetic crystals inside the red blood cells it infects. Normal red blood cells don't have these crystals. So Armani says if you shine a laser light through a sample of uninfected blood and then put a magnet next to the sample, nothing happens.

ARMANI: In contrast, if you have a sample of blood that is infected with the malaria parasite and you put a magnet next to it, the amount of light that can go through that sample will change.

PALCA: The magnet pulls the crystals out of the way so more light can shine through. That change tells you whether the parasite is present. She says the device should be able to detect infections even before someone is showing symptoms. A description of the invention appears in the journal ACS Sensors. There is still a lot of work to be done. Armani is testing her device on animals infected with malaria. Then she'll try it out on infected people. That will take a while. But if you want to change the world, you have to start somewhere. Joe Palca, NPR News.

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