Plastic Origami Field Use Microtome

Plastic origami (plastic folder source) worked well to make specimen holder. 2 widths possible by either folding down on bottom to furthest stop or by placing bottom together in slit cut. Slide holder is filled with water and specimen is hand advanced with the slightest of nudges over the length of the specimen holder. Cuts are made on the other side of the glass slide, which holds the specimen holder in place and also acts to create a smooth cutting surface for better quality cut (using standard razor blade). The glass slide has a semi-ovular cut from the bottom using a steel wheel glass cutter (see video). This cut allows the specimen to advance beyond the glass so that the specimen can be cut. Cross sectional cuts of stem are picked up with needle nose forceps and placed on a slide. Extra water was absorbed with Kim wipes separating slides. Clear tape is used as cover slip to secure specimen to slide and then specimen are examined using Carson handheld microscope.

Microtome design is derived from OPN handheld Microtome. https://pages.stolaf.edu/wp-content/uploads/sites/803/2017/04/Giannini_OPN_Microtome_Manual_20170415.pdf

Glass cuts were informed by the following video. https://www.youtube.com/watch?v=1D0XLXVkJKE&list=RDQMt9myRA9-BI4&start_radio=1

It may also be possible to use thin shaving razors for specimen sectioning. I cite the following as inspiration: http://www.microscopy-uk.org.uk/mag/indexmag.html?http://www.microscopy-uk.org.uk/mag/artapr04/wdslicera.html

Plastic origami Microtome folds achieved as follows: fold plastic sheet, obtained from plastic folder cut, in half. Measure 1 cm on each side of fold and fold 1 cm lines opposite of half fold line. Finally, fold remaining length, on each side, using the "V" of center fold. Cut 1/2 cm slits at the halfway point of the length of the Microtome channel. The length of the channel should be measured to fit snugly between the glass slide inserted within the slide case and the short wall of the slide case. Enough space should be left on the non-specimen portion of the glass slide to make a specimen cut.

It may be necessary to come up with a new cover slip solution as what was viewed in the Carson handheld microscope was lacking in resolution. At the same time, it may just be that thinner sections need to be achieved (through practice).

Specimen advance function added to plastic origami Microtome system. 1/4 20 thread 3 in screw w/ added wing nut and securing but for thumb loosening and tightening. 7/32 drill bit used to drill hole in plastic so that plastic could be threaded. 7-11 slurpee straw used for bolt casing, the "slide end" contains the advanceable specimen. Useful for specimen ~3/8 in diameter. Shown here I am sectioning a twig of the giant oak in our yard.

Needed to craft a second microtome specimen holder for leaf sectioning. Basically, as described in the OPN microtome guide, a leaf is sandwiched between to foam tape sections and the specimen sandwich is placed in the rectangular bottomed specimen holder. Sectioning works as with the triangular framed bottom. I include some dimension info here but the specifics of dimensioning will be particular to your slide holder. Here I use a 25 slide holder and use dimensions of ~8 cm X ~5 cm for the specimen holders.

Had to make a new flat bottom specimen holder as 1 cm was too wide to hold the sandwich for leaf sectioning. The new specimen width was measured according to the thickness of the Scotch Mounting tape shown below (~1/3 cm for sandwich with leaf). The height of the specimen sandwich needs to also be considered because it needs to clear the "moon cut" in the glass slide. Because of this I will attempt to make a few different slides with differing heights to be used for different sample sizes. Of course, the higher the cut the more sensitive the glass slide is to breaking in half, and the more the width of the cut needs to be, which means it may extend beyond a razor blade's width. Using wider razor blades also means using thicker razor blades, which increases the thickness of a specimen section.