NIST microscope tracks nanoparticles in 3-D

A patent-pending microscope substrate design developed at the National Institute of Standards and Technology (NIST; Gaithersburg, MD) allows nanotechnology researchers to track the motions of nanoparticles in solution as they move around in three dimensions.

In simple imaging microscopes that see a three-dimensional (3-D) fluid volume as a two-dimensional (2-D) plane, how far a particle is above or below the focal plane can only be estimated. The NIST alternative uses angled side walls of a specially designed microscopic sample well (20 µm square and 15 µm deep) that act as mirrors to reflect side views of the volume up to the microscope at the same time as the top view. The microscope sees each particle twice—one image in the horizontal plane and one in the vertical. Because the two planes have one dimension in common, a simple calculation is performed to correlate the two and reveal the 3-D path for each particle. Knowing this 3-D information (as well as the simpler 2-D position) to better than 10 nm should improve the understanding of nanoparticle self-assembly processes. Contact Matthew McMahon at [email protected].