In a new study, researchers showed that using sound waves to levitate droplets of water in midair can improve the detection of harmful heavy metal contaminants such as lead and mercury in water. Detecting small amounts of heavy metals in water is important because these contaminants are harmful to human health and the environment. The new technique could eventually lead to instruments that perform real-time, on-site contaminant monitoring, which could help prevent future lead contamination problems like the Flint, Michigan, water crisis or detect contaminated wastewater from industrial sites.