Harvard Medical School scientists have developed a miniaturized handheld nuclear magnetic resonance (NMR) scanner that can diagnose diseases and identify pathogens, and is 800 times more sensitive than standard NMR scanners used in many laboratories — enough to detect just 10 bacteria in a given sample.

The trick is the use of magnetic nanoparticles, which generate a much larger signal than single nuclei, and coating these nanoparticles with molecules that bind to specific biomolecules, bacteria, and viruses.