Lima, F.P., and D.S. Wethey. 2009. Robolimits: measuring intertidal body temperatures using biomimetic loggers. Limnology and Oceanography: Methods 7:347-353.
Step 1: Disassemble the IButtons
Step 2: Remove Circuit Board and Solder
I then soldered some small sections of wire which I took out of an old phone cord. There are three contacts. The left is negative, the middle is positive and the right is the I/O contact. I soldered these wires to the negative and I/O contacts. See the Lima & Wethey article for an excellent depiction of this.
Step 3: Solder on Constantan Wire
Once cooled, slide the circuit board back into place.
Step 4: Drill Holes in Shell
Step 5: Fit Sensor to Shell
Everything should fit inside and nothing should stick out beyond the depth of the shell. It may same some adjustment of the wires and a couple times I had to re-solder them.
Now is a good time to test the temperature sensors to make sure they still work.
To test the sensor, use a pair of alligator clips connected to a phone wire which then connects to a RJ-11-to-USB adapter. These adapters can be purchased from most suppliers of iButtons. Here, I connected the alligator clips to the red and green wires
Step 6: Pouring the Scotchcast
Prop the limpet shells on their back, toothpicks worked just fine here to make sure they stay level. The constantan electrodes also helped to support and keep the edge of the shell level.
Mix 3M Scotchcast 2130 Flame Retardant Compound as specified on the package.
Clearly, its easy to make a huge mess with this stuff. Two main lessons learned:
1) Before mixing, the scotchcast has the consistency of cold molasses. After mixing, it warms up and is viscous like oil coming out of a warm engine.
When you're ready to pour, I recommend cutting a fairly small hole in the scotchcast to give you more control over the pouring process.
2) Although purchasing the larger 21.7 oz bag may make economic sense, you will probably only need the 7.6 oz bag for every 10-15 of these sensors.
Fill the shells completely and be sure nothing is protruding through the scotchcast.
Since I made a mess of things, I had to scrape off a lot of scotchcast that had gotten onto the outside of the shells.
Let them sit overnight and verify that the sensors still work in the morning. All 10 of the sensors I poured here, worked just fine when it was done.
Step 7: Deploying Robo-limpets
Once they are ready to deploy, use A-788 Z-Spar Splash Zone Compound to attach the sensor to a boulder. I used a paint stirrer to mix about a tablespoon of part A and part B of the Z-spar in a little disposable container. The Z-spar was then applied to the bottom of the robo-limpet using my fingers while wearing a glove. I used enough Z-spar to cover the entire bottom of the shell, then pushed it into place on the boulder.
I scrapped away any excess using a popsicle stick.
To download the data, just attach the alligator clips to the robo-limpet and the USB adapter to a laptop.
Step 8: Bye
If you have any questions, please feel free to ask.