Open Source Underwater Distributed Sensor Network

One way to design an underwater monitoring device is to take inspiration from nature and emulate an underwater creature. [Michael Barton-Sweeney] is making devices in the shape of, and functioning somewhat like, clams for his open source underwater distributed sensor network.

Underwater distributed sensor network descent and ascentThe clams contain the electronics, sensors, and means of descending and ascending within their shells. A bunch of them are dropped overboard on the surface. Their shells open, allowing the gas within to escape and they sink. As they descend they sample the water. When they reach the bottom, gas fills a bladder and they ascend back to the surface with their data where they’re collected in a net.

Thus far he’s made a few clams using acrylic for the shells which he’s blown himself. He soldered the electronics together free-form and gave them a conformal coating of epoxy. He’s also used a thermistor as a stand-in for other sensors and is already working on a saturometer, used for measuring the total dissolved gas (TDG) in the water. Knowing the TDG is useful for understanding and mitigating supersaturation of water which can lead to fish kills.

He’s also given a lot of thought into the materials used since some clams may not make it back up and would have to degrade or be benign where they rest. For example, he’s been using a lithium battery for now but would like to use copper on one shell and zinc on another to make a salt water battery, if he can make it produce enough power. He’s also considering using 3D printing since PLA is biodegradable. However, straight PLA could be subject to fouling by underwater organisms and would require cleaning, which would be time-consuming. PLA becomes soft when heated in a dishwasher and so he’s been looking into a PLA and calcium carbonate filament instead.

Check out his page where he talks about all these and more issues and feel free to make any suggestions.

Excuse me iPad, may I cut in?

[LostSpawn] loves his clamshell keyboard for the iPad, but he had one major beef with the design. When the tablet is installed in the landscape orientation there’s no way to plug in a dock connector for charging or other uses. He pulled out the cutting tools and altered the case to meet his needs.

The case is a Rocketfish iCapsule which provides a Bluetooth keyboard when you need to do a lot of typing. The hard shell does a great job of protecting the iPad, but who wants to pull it out to charge it? The thing that we can’t believe is that there’s a slot milled in the other side of the bezel so that you can plug in headphones. How did they overlook the dock connector?

To add it himself, [LostSpawn] started by drilling a dotted line along the portion that he wanted to remove. He finished shedding material with a Dremel and then set about sanding it flat. To make sure it didn’t look too much like a hack he used Bondo to build up the working edge and then sanded and painted for a factory finish. Now he can plug in the cable or an SD card adapter like the one seen to the right of the keyboard.

Pandora case prototype

The last time we checked in on Pandora it was just being shown in dev unit form. Embedded above is a video of the first case prototype. It doesn’t have any components yet, but it definitely looks like a good formfactor with a lot of potential. The Pandora is a Linux based portable game console with an 800×480 touchscreen.

[via Gizmodo]