Overhead view of the NIST-Cornell 3-D nanofluidic device showing the different depth levels within the chamber as horizontal bands. The deepest, at the bottom, measures about 620 nanometers (slightly smaller than an average bacterium), while the shallowest, at the top, is about 60 nanometers (1,000 times smaller than the width of a human hair). The colors of the bands result from different mixing of white light components (interference) at each depth. Nanofluidics is the study of the behavior, manipulation, and control of fluids that are confined to structures of nanometer characteristic dimensions. Fluids confined in these structures exhibit physical behaviors not observed in larger structures, such as those of micrometer dimensions and above, because the characteristic physical scaling lengths of the fluid, very closely coincide with the dimensions of the nanostructure itself.