Team:Cornell/notebook/drylab/august

Entry:

This evening in the ECE lab, Lydia and Kelvin continued working on their respective tasks, while Manny and I discussed ways to fix the solar panel to the case.

The most promising design is to make L-shaped brackets out of Plexiglass or Lexan. The bottom of the L’s would be adhered to the case with some kind of plastic welder. It would raise the solar panel a little bit from the case surface, giving enough space for the water tubes and wires to come through the hole underneath the panel. The solar panel would be bounded to the case by its wire, which would be taped to the inside of the case. The influent and effluent tubes would be fixed between two brackets in opposite directions. Thus, there are 2 L-brackets that run longitudinally along the solar panel, and 4 smaller L-brackets that run latitudinally--2 on each side, with a tube running between each pair.

The other designs are simpler to implement, such as using elastic bands that run around and underneath the lid and zip-tying the solar panel to the case handles (the solar panel frame has holes for zipties to run through). Some other materials we are interested in getting include paracord rope.

#chassis #solar panel

Entry:

Manny and I met up after lunch on this warm, cloudless day to run tests on the Pelican case. We wheeled the case out of Rhodes Hall and into the nearby trees. It easily passed the field deployment test. The wheels held up well against the rough path of pebbles and gravel and the handles made it easy for us to carry the case down the steps. When we got to the stream, we slid the case into the water and unsurprisingly, it floated fine.

To test the watertightness of the case, we loaded about 50 pounds worth of rocks into the case before tossing it back out, making sure the case opening was below water surface. With 50 pounds inside, the case was still floating. As Dan mentioned in a previous meeting, it should still be able to float with all our equipment inside. After about 10 minutes, Manny and I dragged the case out to find no detectable amount of water content inside.

Dan had also wanted us to see whether a phone would still be able to reach the network inside a submerged case. Despite results from the waterproof test, neither Manny nor I wanted to risk our own phones, so we roshamboed to decide whose phone (see en.wikipedia.org/wiki/Rock-paper-scissors). Roshambo master that I am, Manny lost and reluctantly put his phone inside the case and held it down under water. Shortly after, I called his phone and Manny felt his phone’s vibration through the case. Completing the final test, Manny scrambled to pull his phone out of the case before we headed back.

#chassis

Entry:

In Duffield, DryLab members met with several WetLab members to update them on what DryLab is currently working on. Afterward, Eric met with the website subteam to discuss the story and graphics of website. Meanwhile, Maneesh, Manny and I went to Clark Hall to pick up the bioreactor and later headed over to the ECE lab to test it out. The micropump was able to pump water out of the reactor without any leaks.

#website #micropump

Entry:

Manny and I spent the first few days of the week in the Emerson machine shop making caps and bodies for the bioreactors. We successfully press fitted the caps into the clear tube body and tested them for leaks. We screwed the luer locks into the caps after completely filling the reactors with water. We tried various orientations, and found to our satisfaction that everything was tightly sealed. However, when we tried to push water through the bioreactors using the micro-pumps, the pumps failed to overcome the water pressure. Disappointed, we began to look for stronger, more robust pumps to do the job.

We also encountered an issue with preventing leaks from the two graphite rods running through the front cap. To seal the cap holes for the rods, we drilled through the luer locks and ran the rods through after they were fitted with rubber sleeves. Water was able to seep through between the rubber and the plastic luer lock. As a solution, Dan and Manny attempted solder on a thin coating, but when that proved too difficult, melted the rubber and plastic to purge any gaps. Still, water was able to get through. Ultimately, Maneesh’s application of silicone sealant between the luer locks and graphite rods accomplished the objective.

Although there is still a lot to do before the system is ready to be deployed, everybody has worked diligently in their groups this summer. Thus, next week, many of us will be taking off to enjoy what little remains of the summer.

#bioreactor #leaks #vacation

Entry:

With regards to the previous entry, Maneesh was able to fix the leak involving the graphite rods with weatherproofing silicone sealant. However, the sealant shrank in the autoclave. As the ultimate solution, we will seal the bioreactor caps with Underwater and High-Temperature Gasket-forming sealant.

Additionally, we have finally received funding from ConocoPhillips. Unlike during the summer, we no longer have to keep a tight leash on spending and can move forward with ordering a full inventory of parts. Dan has been diligently making an order list, which includes several kinds of filters. We will need to filter out sediment and foreign microorganisms in the water entering the system, as well as prevent Schewanella from leaving the system.

Over the summer, Maneesh has looked for methods of sterilizing the tubes to prevent bacteria from building up inside the tubes, given our constraints on energy and volume space. One possibility is to line the tube walls with silver ions which are naturally antimicrobial. We can run a low electric current to increase potency. Another idea is to have clear tubing wrap around a UV light source to increase the length of the tube that can be sterilized. Chie is currently finding UV lamps that could be implemented into our device.

During these last days of vacation, Dan suggested a new system for tracking the division of labor for the upcoming semester. He will introduce these plans in the next general body meeting. Meanwhile, I hope everybody has a short but well-deserved break!

#bioreactor #waterproofing #sterilization #benjamins

Entry:

Today marked the first full team meeting of the fall semester. It was good to see the old members who did not stay over the summer, such as Jim, Charlie and Bill. Jim informed us that the team would be restructured a bit; people had to choose between dry lab and wet lab. Thus, dry lab lost Chie and Tina, who have been in both subteams over the summer. Additionally, Dan introduced new rules for dry lab for the fall semester. Starting now, we have to log in our hours on a weekly chart, and work for a minimum of 6 hours per week or until the completion of the assigned task. Since the project team counts for 3 course credits, the grades will reflect how well members execute their responsibilities and contribute to the team.

On a lighter note, Dan showed everyone how the solar panel attaches to the Pelican case. Four surrounding L-brackets prevent the panel from shearing off the case, while military velcro between the panel and case impede the panel from lifting off the case. Personally, I think that the velcro is an ingenious idea as it allows users to separate the panel with the right amount of force. Additionally, three filters that Dan ordered the previous week sat in the case, ready to be hooked up to the system. Although they seem a bit bulky, the filtration units have meters that indicate when the cartridges are full of debris. Furthermore, the cartridges can be easily removed and replaced.

With the funding received from ConocoPhillips, we are looking to buy a device that will mix the food and analyte water that will be fed into the bioreactor for the Schewanella. Through a bit of research, we concluded that the simplest option would be an inline static mixer, a tubelike structure with chambers to mix the passing solution. We also needed to account for pressure drop, a detail that we realized dry lab overlooked all summer. After finding our system has laminar flow, we used an online resource to match our flow rate to approximately 0.033 milliliters per minute. The low flow rate means there will be a negligible pressure drop if we choose a maximum number of elements or mixing fins. Rest assured, our microscopic pets, food and analyte water will be well mixed before served.

#mixer #food #pressure drop #tubing #reunion #welcome back