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, infrared 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-millimetre per second. By comparison, current ultrasound technique can't accurately detect anything under 10 millimeters per second. Next up: human testing. And apparently it won't hurt a bit. [Physical Review Letters via New Scientist]
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