Sonar Technology for Liquid Forensics to Determine Quality of Water and Beverages; Motor Oil Too!

    By Kathleen Berger

    The water you drink may come from a public water system or private well. Or you may drink bottled water. Depending on the source, different measures are taken to ensure the water you are drinking is safe and healthy.

    In development at the University of Missouri, sonar technology is used to analyze small drops of liquid samples.

    “If the water isn’t drinkable, then our method will tell you that something is wrong with the water,” said Luis Polo-Parada, PhD, associate professor of pharmacology and physiology in the MU School of Medicine.

    MU researchers designed an instrument to analyze the quality of liquids using the photoacoustic effect. Scientists say it’s a rapid and inexpensive way to determine if drinking water is safe to consume. Sonar technology can determine changes in the physical properties of liquids. This helps to identify water quality.

    “Let’s say you’re monitoring the desalination of water, with the speed of sound you can very easily detect minute qualities of salt in water,” said Gary A. Baker, PhD, associate professor of chemistry. “You can use this as a quality control feedback to determine the water has met the expectations of the desalination process.”

    The research technology is comprised of a laser tattoo removal machine and a microphone for the generation and recording of sound waves after light is absorbed in the liquid.The tattoo removal laser sends brief flashes of light, each lasting about 10 nanoseconds, through a fiber optic cable submerged in the small drop of the liquid sample. The cable’s end converts the laser light into sound. The microphone records the sound and the data is analyzed in real-time.

    By analyzing the sound, researchers can determine the quality of the liquid. They can detect if something is wrong with the water and not drinkable. The research team used the sonar technology on a variety of other liquids.

    Drops of seawater, dairy milk or ionic liquids, a class of molten salt, were used in the study. The MU scientists believe this might be the first use of this technology to analyze such small liquid samples.Baker said before the development of the lab’s sonar technology, there was no way to measure speed of sound in tiny volumes of liquid.

    “It’s a quantity we want to know for a lot of practical reasons. You can get some fundamental features about the properties of a liquid by measuring speed of sound,” Baker said.

    He explained the technology could one day be used by food and beverage regulatory agencies to check product quality, such as ensuring the quality of milk processing or checking the percentage of alcohol in alcoholic beverages. MU scientists say it could be used to determine the quality of honey and the amount of sugar or sugar substitutes in soft drinks.

    Researchers give more examples for the use of the technology, such as detecting the amount of inferior oil in fraudulent olive oils and determining the quality of motor oils and other vehicle fluids.

    The team is now working to refine its recording methods and equipment to provide commercial industries with an inexpensive way to monitor the quality of liquids.

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