Weighing Molecules One at a Time

This scanning electron micrograph shows one of the molecule-weighing devices. The bridge-like section at the center vibrates sideways. The scale bar at the bottom is two microns (millionths of a meter).

[Credit: Caltech / Scott Kelberg and Michael Roukes]

A team led by scientists at the California Institute of Technology (Caltech) have made the first-ever mechanical device that can measure the mass of individual molecules one at a time.