V. Tape well slides

Purpose of tool:

            Tape well slides are well suited for non-destructive observation of small organisms that are encapsulated in a relatively thin and uniform plane of focus. The slides are especially useful for viewing living, whole specimens of aquatic oligochaetes, such as Lumbriculus variegatus (Drewes and Lesiuk, 1999). These worms are thigmotaxic, and thus prefer refuge in the narrow space between the floor of the well slide and the cover slip. These well slides are also excellent for viewing water samples containing microorganisms such as protozoa, rotifers, nematodes, etc. 

Required materials:

Clear plastic tape [Brands: (1) Frost King clear plastic weatherseal tape; 2 in x 100 ft roll; sold at home improvement stores, or on-line at: http://www.castlewholesalers.com/

(2) Scotch Colored Plastic Tape: Clear, Cat. #190; 0.75 in x 125 in

Metal straight edge ruler

Sharp-tipped forceps

Marking pen

New, single-edge razor blade

Heavy scissors

Heavy-duty, flexible clear plastic [Suggested materials: Lexan clear polycarbonate sheet (30 mil thickness), or extra-heavy clear plastic lamination sheet, or thin plexiglass][Alternate: glass microscope slides]

Assembly and use of this tool:

1. Use a marking pen and straight edge ruler to mark off the desired rectangles that will become the floors of the tape well slides (Fig. 10).

2. Carefully align a long strip of clear tape over a series of the rectangles, as shown in Fig. 10.  If wide (2 in) tape is used, it is important to minimize air bubble formation under the tape. To minimize such bubbles, use one finger to press down and smooth the tape, beginning at the center line of the tape and working outward toward the outer edges.

3. Add multiple layers of tape, as desired.

SPECIAL NOTE: Each layer of Frost King weatherseal tape adds approximately 75 microns (0.075 mm) of depth to the well. Each layer of Scotch Clear Plastic Tape adds approximately 60 microns (0.060 mm) of depth to the well. Three layers of weatherseal tape nicely accommodate average-sized blackworms (Lumbriculus) in the wells.]

4. Using a metal ruler and new single-edge razor blade, make vertical cuts through the tape layers, as shown in Fig. 11. These cuts define the well size. Make sure cuts are overlapping at the corners. This insures easy removal of the tape that covers the well.

5. Now, insert the tips of a sharp-tipped forceps under the corner of tape covering one well.  Lift the corner of tape to remove all tape layers covering the well (Fig. 11).
    
6. Next, use a heavy scissors to cut out the rectangles from the sheet.  Use a single-edge razor blade to trim away any tape that extends over the edges of the cut rectangles.
    
7. Cut two narrow strips of tape and attach them to the underside of the well slide, as shown in Fig. 12. These tape strips act as spacers or feet that slightly elevate the well slide above the microscope viewing stage, thus helping to reduce scratching or marring of the floor of the well slide.

Figure 10. Rectangles on transparent sheet covered by multiple layers of clear tape.

Figure 11. Suggested position and size of cuts for tape well slides.  Note that forceps tips are used to pry up the tape at one corner of the well.

8. On a clear transparent sheet, mark off a series of rectangles that define the cover slips to be used over the tape wells.  The size of the cover slips should be larger that the well but slightly less that the length and width of the tape that it will rest on (see Fig. 12).

9. Use a plastic pipet (or stretch pipet, as shown in Figs. 7 and 8) to place a living specimen in the well, along with a few drops of water.

10. Cover the fluid-filled well with one of the cover slips made in step 8. Press slightly on the cover slip and tilt the slide sideways to drain off excess water drops. Now, the specimen is ready for viewing

11. CAUTION: Be sure the microscope light does not overheat organisms in the well slides.

12. After making observations, carefully slide the cover slip off the well and use a pipet to flush the organism back into its original container.

13. Wells should be rinsed thoroughly in distilled water and air-dried.

[Cost is less than 10 cents per well slide. Assembly time is less than 10 min/unit.]

Figure 12. Completed tape well slide showing size and position of cover slip.  Note the tape feet on the underside of the well slide (dotted lines).