The monitor displays several unusual clusterings of micron-sized colloidal spheres in water. The clusterings are unusual in that the spheres are all negatively charged, and should be repelling each other strongly. For some reason, they aren't. When the electrodes are turned on, a slowly oscillating electric field is formed, causing the spheres to compress against the glass and form polycrystalline layers. The whole apparatus is mounted on an inverted microscope which has a video camera attached, so that the behavior of the colloidal spheres can be easily observed and recorded.
Every precaution is taken to prevent contamination.
Mixed bed ion exchange resin is introduced to the suspension via glass reservoir tubes to reduce the concentration of stray ions from the surface of the glass plates, and the reservoir tubes themselves are continuously flushed with humidified Argon to prevent contamination from the air. When that field is turned off, the suspension quickly returns to the equilibrium fluid state - at least, most of the time. Larsen and Grier, however, have seen colloidal crystals remain intact for up to an hour after most of the suspension has returned to a fluid state - even though the colloidal spheres have like charges and have no reason to cling together in the absence of an electric field. How the metastable crystallites remain intact for so long is not yet understood. Their longevity is not caused by the inhomogeneities in the properties of the glass surfaces, because the crystals are observed to drift across the glass surfaces on which they form.