The 16-capillary instrument is based on a micromachined cuvette, in which a set of fingers are machined into the front and back walls of the flow chamber. A precisely etched and polished microscope cover slip serves as a spacer between the front and back wall of the cuvette, so that the capillaries are held snugly. The cover slip also serves as a window to allow entrance of the laser beam

      The fingers hold the capillaries in precise registration, which results in uniform flow in the cuvette, as can be seen in the figure below. The right-most stream is distorted because we forgot to include a space between that capillary and the cuvette wall. As a result, the sheath fluid velocity was lower on that side of the capillary, creating the distorted flow pattern. Later designs corrected this flaw.

      In this image, we intentionally generated scattered laser light to illuminate the capillary array, which glows as vertical gold rods. Scattered light is blocked with a filter; the blue laser beam generates yellow Raman scatter, which is the vertical beam in the figure. Fluorescence from analyte migrating from each capillary is visible as a yellow spot beneath the outlet of each capillary. Last, the glass from which the cuvette was manufactured produces a red luminescence when illuminated by the laser beam, which is visible at the far left and right of the figure.
      The 16-capillary instrument used a microscope objective to collect fluorescence and image it on a set of fiber optics. The objective was operated well beyond its designed field-of-view, which resulted in a severely curved image. The GRIN-lens coupled fiber optics were set in position so that the fluorescence was sharply imaged, and the optics fell in a parabola.

      The instrument used home-built, high-gain transimpedance amplifiers for the avalanche photodiodes, which were housed in an electromagnetic shield box to minimize interference. The photodiodes were also held at -20 degrees C. The instrument was constructed in Edmonton, and on far too many days, the instrument was heated to -20 C with respect to the outdoor temperature.
      Of course, we have used this instrument for generation of DNA sequence data, and the first sequence data submitted to Genbank was obtained with this instrument (accession number AF053570). The figure below shows some sequence data from heat-shock proteins.
      A photograph of our 16-capillary sequencer was featured on page 995 of the 1998 May 15 issue of Science. A publication describing the instrument was published as "Capillary array DNA sequencer based on a micromachined sheath-flow cuvette" H.J. Crabtree, S.J. Bay, D.F. Lewis, L.D. Coulson, G. Fitzpatrick, D.J. Harrison, S.L. Delinger, J.Z. Zhang, and N.J. Dovichi, Electrophoresis 21, 1329-1335 (2000).