Researchers at the National Institute of Standards and Technology (NIST) have recently discovered how to measure the volume of droplets smaller than 100 trillionths of a liter with an uncertainty level under 1%, a significant step in improving the understanding of how viruses such as COVID-19 spread.
Scientists at NIST calibrated a normal optical microscope and used it to measure the volume of individual microscopic droplets with an accuracy 10 times better than that of previous technologies, a NIST news release said.
“Measuring the volume, motion and contents of microscopic droplets is important for studying how airborne viruses spread (including those that cause COVID-19), how clouds reflect sunlight to cool the Earth, how inkjet printers create finely detailed patterns, and even how a soda bottle fragments into nanoscale plastic particles that pollute the oceans,” NIST said in the release.
The team also created a system to measure microdroplets in flight using a technique known as gravimetry, the release said.
“Gravimetry measures volume by weighing the total mass of many microdroplets that accumulate in a container,” NIST said in the release. “If the number of droplets is controlled and the density – mass per unit volume – is measured, then the total mass registered on a scale can be used to calculate the average volume of one droplet. Although this is valuable information, because droplets can vary in size, imaging single droplets by optical microscopy enables a more direct and complete measurement.”
NIST said that calibrating the microscopes so they could better detect a droplet’s edge, which is necessary for finding their dimensions, was what made the accomplishment possible.
