Collar Design
Thomas
Wassmer, Siena Heights University, Adrian, MI 49221, twassmer@sienaheights.edu
(Based on a
design communicated by Cindy Canale)
Fig.1
To protect the iButton from
humidity and precipitation, it is first encased into a special wax that is
resistant against microbial growth and stable in a variety of ambient
temperatures: Paramat Extra – in the US available at: Paramat Extra, Electron
Microscopy Sciences, Hatfield, PA. The iButton is coated 3 times by briefly
submerging it into the melted wax at a temperature between 70-80 C. For this purpose I use an inoculation loop
(Figure 1 and 2). Make sure to turn the iButton on the opposite side during
each coating process, let it briefly harden (30 seconds) and form it between
your fingers by gently pressing the wax against the iButton between coatings.
Fig. 2
Figure 3: Waxed iButton
Figure 4: First collar design with boxy casted epoxy casing
and ordinary 90° cable ties. Collar often sat crooked on the animal’s necks due
to the 90° tie exit and could pinch in skin. The boxy casing contributed to
these problems.
Figure 5: Design improvement
using zero-degree cable ties as suggested by Chris Kochanny formerly from Lotek.
The paper clip marks the position of the data logger. As you can see, these
cable ties form a perfectly round loop.
Figure 6: To improve the boxy
design, I went to an epoxy putty that could be hand formed. This modification
was suggested by John Edwards from
Holohil Systems. In addition this design used the zero degree cable ties. Due
to the high content of bisphenol A (BPA) in every epoxy resin, which is known
to be a powerful endocrine disrupter, I hunted for a different plastic that
could still be hand-formed.
Figure 7: I found my final
casing material in the new generation dental acrylic. A local dental lab
recommended Jet Tray, Lang Dental Manufacturing Co., Wheeling, IL. As the
polymerization of acrylic produces heat, I needed to first make sure that the
heat would not increase the above 80 C and damage the iButton, which was
luckily not the case.
Figure 8: Before attaching
the iButton with the resin, a piece of heat shrink was added between the cable
tie latch and the optimal position of the casing (marked with a piece of
masking tape). Also note that the iButton needs to be attached to the inside of
the closed cable tie.
Figure 9: A strong paperclip was used to loop the cable tie before the acrylic
hardened. This allowed the attachment to be curved instead of straight.
Figure 10: After 24h of hardening, a dremel tool was used to smoothen and round
any sharp corner of the acrylic casing.
Figure 11: Final design of the casing made out of dental
acrylic resin attached to a zero-degree cable tie. Note the smoothened surface
after using the dremel tool, and the partially shrunk heat shrink attached to
both limbs of the casing.
Figure 12: Squirrel 104 with collar 7 caught on May 22, 2013
between 12:15 and 14:20 ET.
Figure 13: Squirrel 133 carrying collar 4b, caught on May 1,
2013 between 11:30 and 12:30. Please note the phone number on the heat shrink
to allow lost devices to be returned.
Figure 14: Retrieved collars are carefully opened using a
hacksaw, a straight head screwdriver and a spatula.
Figure 15: The retrieved iButton is ready for data
extraction.
