(NIST: Gaithersburg, MD) -- A wrench or a screwdriver of a single size is useful for some jobs, but for a more complicated project, you need a set of tools of different sizes. Following this guiding principle, researchers at the National Institute of Standards and Technology (NIST) have engineered a nanoscale fluidic device that functions as a miniature “multitool” for working with nanoparticles—objects whose dimensions are measured in nanometers, or billionths of a meter (see figure 1).

Figure 1: A  3-D nanofluidic “staircase” channel with many depths was used to separate and measure a mixture of different-sized fluorescent nanoparticles. Larger (brighter) and smaller (dimmer) particles were forced toward the shallow side of the channel (fluorescence micrograph on left). The particles stopped at the “steps” of the staircase with depths that matched their sizes. Credit: S.M. Stavis, NIST

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