12 Jun

Fourth Installation: SLA Beeber


Students at Science Leadership Academy’s Beeber campus installed Root Kit #4 yesterday, capping off an 8-week minicourse of designing and building the sensor housing, soldering the kit’s circuit board, testing radio signal strength, and troubleshooting along the way. Remember the waterlogged sensors from a few posts ago? We did an immersion test and found out water was leaking into the Pelican case at the base of the cable glands:


We used a combination of Rust-oleum Leak Seal spray (not that effective, smells toxic) and silicone caulk (it works, but it’s messy-looking) to waterproof the case. After connecting to the school’s network and testing signal strength from the flowerbed to the 3rd floor office, students buried the soil sensors:


The students went with the eyeball housing for their site, and designated the rocketship design for a future installation at the Franklin Institute this summer (details to come). We poked a pinhole into the eye’s center to allow the antenna to peek out:


Thank you to all the SLA students, Mr. Sokoloff, Darya Drahun and Sandy Sorlien—mission accomplished!

05 Jun

Third Installation: Greenfield Elementary


The sword in the stone now sits among other stones at Greenfield Elementary School. This stone, however, hides a Root Kit, sending soil moisture data to our growing tree. A slight modification was made to the stone when we drilled a pinhole in the top for the Root Kit’s antenna to poke out. Increasingly, we’re finding out that a line of sight between the two antennas is an important factor in keeping the radio signal alive. (For a refresher on how this set-up works, go here.)

Thanks to Mr. Bentz and his 8th grade class, who buried the sensors; and to Drexel co-op Darya Drahun for technical assistance. We noticed during our visit that Greenfield is installing a green roof directly below the science classroom; this would be a fascinating new home for the sensors next year.


03 Jun



Mysteriously, the sensors at Nebinger and Cook-Wissahickon elementary schools stopped transmitting data late last week. A trip out to each school’s garden quickly revealed the problem: waterlogged Root Kits, with circuit boards and battery cases floating in water. Weren’t these things supposed to be waterproofed? Not against last week’s heavy rain, apparently. We have a hunch as to where the water is getting in; students at SLA Beeber will conduct an immersion test (i.e., put the case in a bucket of water) to see where the water is leaking in and recommend fixes. But for now, the Root Kits are sidelined and drying out, and we’ll test the circuit boards to see if they still work. Check out the futility of the dessicant pack in the photo below:waterlogged_RootKit2