Currently, doctors use ultrasound to measure blood flow in the body. Doppler effect, just like bats! But it can't detect flow in the small, slow moving vessels where diseases often start. The solution? Sonic blasts that heat up a tiny drop of blood, then watch where it goes. Science!
While this might sound like a comic book villain's torture device, according to researchers at Washington University in St. Louis, you'd only feel a slight warming sensation from the focused ultrasonic blasts heating up your vessels. Meanwhile, infra-red laser pulses bounced off the warmed blood would be picked up by the ultrasound, delivering real time flow data. New Scientist likens it to dribbling a drop of ink in a stream of water to determine the speed and direction of flow. Except, y'know, with hot blood instead of ink.
In experiments, the technique accurately measured blood flow as slow as a quarter of a millimetre per second. By comparison, current ultrasound technique can't accurately detect anything under 10 millimetres per second. Next up: human testing. Apparently it won't hurt a bit. [Physical Review Letters via New Scientist]
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