Skip to main content

Scientists use bounced lasers to determine whether a glass of water is pure

Testing Liquids at the Speed of Sound

From DIY water-testing kits to checking out the U.S. Environmental Protection Agency’s databases, there are various ways you can go about testing whether or not water is safe to drink before you elect to pour it down your throat. Scientists from the University of Missouri and Mexico’s Universidad de Guanajuato have come up with an alternative solution — and it’s a high tech doozy!

Their approach involves using a tattoo removal laser machine to flash out a series of brief bursts of light, each lasting around 10 nanoseconds. These flashes of light travel through a fiber optic cable, which is wrapped on one end with paint-on liquid electrical tape. The cable’s end is submerged in the liquid to be tested, converting the laser light into sound. The sound is recorded by a microphone, and the data analyzed in real time.

In short, it uses sonar technology to measure the purity of liquid. It does this by measuring the length of time which passes between each laser flash and the sound reaching the microphone. This allows the researchers to work out how quickly sound waves are traveling in the water — which lets them establish whether there is something in the water that is causing the sound waves to not move as fast as they should.

“This phenomenon is known as the photoacoustic effect,” Dr. Gerardo Gutiérrez Juárez at the Universidad de Guanajuato, told Digital Trends. “The photoacoustic effect is the generation of sound with light. If the PA effect is produced by a nanosecond or pulsed lasers, the frequency of generated sound is in the range of the ultrasound. … With our technology, we can measure the velocity of sound in fluids. This physical magnitude is very important because is correlated with other physical magnitudes like density, which are hard to measure.”

What the technology doesn’t do — unless some other liquid analysis technologies we’ve covered — is to tell you what is present in the liquid. It will tell you whether a liquid sample is as pure as you hope it to be, but not what is contaminating it or the concentration of this contaminant. It is a quick and easy method of forensic quality control.

A paper describing the work, titled “Laser-induced sound pinging: A rapid photoacoustic method to determine the speed of sound in microliter fluid volumes,” was recently published in the journal Sensors and Actuators, B: Chemical.

Editors' Recommendations

Luke Dormehl
I'm a UK-based tech writer covering Cool Tech at Digital Trends. I've also written for Fast Company, Wired, the Guardian…
This AI cloned my voice using just three minutes of audio
acapela group voice cloning ad

There's a scene in Mission Impossible 3 that you might recall. In it, our hero Ethan Hunt (Tom Cruise) tackles the movie's villain, holds him at gunpoint, and forces him to read a bizarre series of sentences aloud.

"The pleasure of Busby's company is what I most enjoy," he reluctantly reads. "He put a tack on Miss Yancy's chair, and she called him a horrible boy. At the end of the month, he was flinging two kittens across the width of the room ..."

Read more
Digital Trends’ Top Tech of CES 2023 Awards
Best of CES 2023 Awards Our Top Tech from the Show Feature

Let there be no doubt: CES isn’t just alive in 2023; it’s thriving. Take one glance at the taxi gridlock outside the Las Vegas Convention Center and it’s evident that two quiet COVID years didn’t kill the world’s desire for an overcrowded in-person tech extravaganza -- they just built up a ravenous demand.

From VR to AI, eVTOLs and QD-OLED, the acronyms were flying and fresh technologies populated every corner of the show floor, and even the parking lot. So naturally, we poked, prodded, and tried on everything we could. They weren’t all revolutionary. But they didn’t have to be. We’ve watched enough waves of “game-changing” technologies that never quite arrive to know that sometimes it’s the little tweaks that really count.

Read more
Digital Trends’ Tech For Change CES 2023 Awards
Digital Trends CES 2023 Tech For Change Award Winners Feature

CES is more than just a neon-drenched show-and-tell session for the world’s biggest tech manufacturers. More and more, it’s also a place where companies showcase innovations that could truly make the world a better place — and at CES 2023, this type of tech was on full display. We saw everything from accessibility-minded PS5 controllers to pedal-powered smart desks. But of all the amazing innovations on display this year, these three impressed us the most:

Samsung's Relumino Mode
Across the globe, roughly 300 million people suffer from moderate to severe vision loss, and generally speaking, most TVs don’t take that into account. So in an effort to make television more accessible and enjoyable for those millions of people suffering from impaired vision, Samsung is adding a new picture mode to many of its new TVs.
[CES 2023] Relumino Mode: Innovation for every need | Samsung
Relumino Mode, as it’s called, works by adding a bunch of different visual filters to the picture simultaneously. Outlines of people and objects on screen are highlighted, the contrast and brightness of the overall picture are cranked up, and extra sharpness is applied to everything. The resulting video would likely look strange to people with normal vision, but for folks with low vision, it should look clearer and closer to "normal" than it otherwise would.
Excitingly, since Relumino Mode is ultimately just a clever software trick, this technology could theoretically be pushed out via a software update and installed on millions of existing Samsung TVs -- not just new and recently purchased ones.

Read more