Hongjian He

A laser hits the sample, and molecules inside start to vibrate. This vibration heats the material by tiny fractions of a degree. Previously, such heating was considered a nuisance, but now it's used to read chemical composition, like guessing who's coming down the hallway by the sound of footsteps.

Light we can't see but feel as heat turns out to be the key to cellular life. A new type of microscope uses waves 2000–2500 nanometers long, three times longer than red light, and such waves barely scatter in tissue. Thanks to this, the device peers into a tumor spheroid like a flashlight through frosted glass, illuminating individual molecules.