Weighing Molecules One at a Time

Michael L. Roukes, Robert M. Abbey Professor of Physics, Applied Physics, and Bioengineering as well as Co-Director of the Kavli Nanoscience Institute, and colleagues have created the first-ever mechanical device that measures the mass of a single molecule. The device—which is only a couple millionths of a meter in size—consists of a tiny, vibrating bridge-like structure. When a particle or molecule lands on the bridge, its mass changes the oscillating frequency in a way that reveals how much the particle weighs. [Caltech Press Release]