Semester 2- Week 8 Kierstin
In Class:
In Class, we presented our progress and listened to other groups' projects. We also went to get our picture taken for the capstone book.
Project Work:
Dr. Rickard talked with me on Thursday morning. He thought that it would be a good idea to take the resistor plates out of the Ahmed valves and add them to the end of our valve to be the resistances because they are already calibrated to help with unhealthy IOP.
My concern for this is that it neglects our solution to fibrosis. This wasn't the exact problem that we were trying to solve, but I think our previous design definitely helped with it. Dr. Rickard said that fibrosis will start close to the valve and then work out, so it will eventually be a problem, but not at the beginning.
I would be concerned this valve would be harder to implant and would have the same fail rate as the Ahmed valve, but it would be a good valve to test in comparison to our valve to see the functionality.
Brinkley and I drew out this idea and brainstormed what it would look like if we switched to this approach. We would use super glue to vary the resistance. I think that we might not have to vary the resistance though. I think that because there are three valves that are equal, the resistance doesn't have to be varied. At slightly unhealthy IOP only one valve would leak, and then as IOP gets higher, all three would pitch in to lower the IOP. We will test the design this week. This brainstorm also touched on other things we wanted to do, such as testing new sutures and test off of height as well as pressure sensors to maintain consistency.
Lab:
Brinkley and I went into the lab and disassembled three Ahmed valves and took out their plates. Once we figured out how to disassemble them this went smoothly. We had to take the plated part out of a little pocket and then dis-attatch the tubing portion from the housing. We then manufactured one of our valves using the Ahmed plates as the resistance. It took a while to manufacture to make sure non of the tubes got bent during insertion. I had to come up with a different method because the tubes were shorter and there was a plastic component on the end that made it difficult to use the same insertion method. I had to stick one of the thicker needles through the top part of the housing until it came out of the bottom and then insert the tubing into the needle and then pull out the needle so the tubing would stick inside the housing. I had to bend the housing so I could do this for all three Ahmed tubes. I was able to do the top tube like normal because it didn't have a plate attached. The images of the manufacturing are shown below.
Brinkley had to coat the valve in a soft epoxy to make sure it wouldn't leak any fluid at the insertion points.
We also worked on creating epoxy resistors, like we had done last semester in the nose tubing. We tested this with two types of hard epoxy. We put the epoxy in a syringe and then connected the ahmed tubing to the end of the syringe. We then pushed the epoxy through the syringe and needle into the tubing. This was very hard because the epoxy was so thick. The cleaning process of this took a really long time, but we were able to clean all our devices so they can be reused. Epoxy #1 was much thicker than Epoxy #2, so we did not get as much tubing filled with this epoxy.
This was the epoxy that came out of the tube. It was very difficult to extract without breaking. And the second photo is of the epoxy in the valve as the resistances.
The testing of the Ahmed Valve:
Analysis:
We still need to test epoxy #1 and possibly make more of it to test now that we know it can be extracted from the tubing, but this is the analysis on the other valves we tested this week:
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