Jellyfish Part II


With this initial success I became very ambitious and initiated Project JellyFish!

My plan was to make a ziplock baggie webcam that could travel survive as deep as our oceans get.

I found some webcams on sale for Just over $11 each and snapped them up. I soldered them to a Raspberry Pi, chucked them in a baggie of oil and...

The big difficulty was 'potting' the wires into the bag. Most bags are made of polyethylene, either high or low density. HDPE and LDPE are magic! They resist being stuck to. Except to other PE's of course. It isn't difficult to come up with ideas of how it could be cheaply done on mass, just use wires coated in PE and they will melt nicely to the bag making a good seal. It has been harder to do at home.

I ordered a strip sealer from ebay and tried sealing the bag with the wires running perpendicular to the

seal. The sealer melted the bag and sealed the wires in. I made a few small test seals to see how it worked. It seemed good, but they didn't hold up to larger volumes (and weight). In the atmosphere there is more pressure on the joint than there will be in the water because all the pressure is pulling the oil in the bag down. Once in the water, even though the pressure will be higher, it will be even so count as near zero (as far as the seal is concerned that is).

The strip sealer was amazing at sealing the bags even when they were covered thickly in oil.

I bought a glue gun from safeway (no lie). I was lucky in that the glue sticks I bought were partly PE. I squeezed a bead of hot glue onto one half of the bag I wanted to seal with the wires running through the glue. Quickly I sandwiched the other half of the bag ontop and tried to smooth it out. The glue was just hot enough to melt the bag a touch, with out destroying it. It wasn't a perfect seal though, so in the next step I used the strip sealer to put a seal along the glue line. It melted the glue and bag all along the joint making a descent seal. I tried it out, filling the bag with some oil. It did pretty good all things considered but eventually the oil would seep out between the wires and the glue.

sealed with hotglue and then strip sealed.

Jellyfish 0.2.0

Jellyfish 0.2.0 had other problems as well. The webcams I bought on sale had auto-focus but with no manual adjustment (electronic or otherwise) they were unable to focus out of the oil. They did function and they did send images. Blurry and useless images.

As you can see Jf 0.2.0 was stereoptic! Legally Blind Stereoptic but stereoptic non-the-less! Given that my trove of disposable webcams were useless for this project I put them into the weedcam project, which ultimately showed that there was a reason these things were on sale.

Now, humbled, I looked for a new path, to lead me to the mariana trench (but not really) and what did I see? A tiny little dice box with a tinier little web cam, sunk beneath a (again tiny) ocean of oil, 'Sealed' shut with black electrical tape. Woot!

I still needed to 'pot' it and really I needed a frame inside the bag to hold everything together. (The CD I screwed things to in Js 0.2.0 broke apart quickly)

To pot the wires I used a pvc pipe and the OpenROV method, epoxy. Next I cut the corner off a baggie and squeezed the pipe through the opening. Originally I tried using silicone as a type of gasket, with a hose screw clamp thingy, (see picture to see what I am failing to describe here) But it leaked. Not right away, but by the next morning when I ran my finger along the joint it came away wet with oil.

The clamp would not work in the deep any way. Everything else would shrink quicker than the metal and the seal would fail.

Next I switched to Elastic bands. :) I ran a bead of them around the pipe on the 'inside' of the joint, then put another bead around the outside. I say a bead but I mean I ran the elastic around and around flat and tight to its self to get a good smooth surface. (see pic) Weeks later the seal was still dry.:)

This is the general idea

No good.

Testing station

Layered: wires, epoxy, pipe, elastic, baggie, elastic. Hooray!


Some times great things happen when one thinks outside of the box, good luck with your project.