This week, we worked on our second prototype. The main problems we saw in our first prototype were size and lack of durability on the bucket. Furthermore, when tested, it did not generate enough pressure. On the second prototype, we changed multiple components. First, we improved the method of securing the bellows, increasing the durability of the acrylic housings by changing from long, ski-like structures that fit in the wooden baseboard to a square, Lincoln log-type structure. We also replaced the hinged wings with a single board, decreasing cost and increasing the stability of the design. Another change that increased the stability was refraining from cutting the bucket in half so it could better support itself.

Early in the week, we thought it was time to quantitatively test the pressure generated. Initially, we were only getting approximately 70 mm Hg, which is less than 1/3 the pressure produced by the Medela manual pump (229 mm Hg). To find the source of the problem, we began to troubleshoot the bellows system (throwback to the 3D printers!). We searched for any leaks in the bellows and played with different ways of compressing them. We found that the seal with the acrylic was not complete and the bellows would pop up at the end of a stroke, which decreased the maximum potential pressure generated. To fix this, we superglued the bellows to the acrylic. We found other leaks in the seal at the top of the bellows and the connection with the tygon tubing. We also discovered that the pressure is greatest when there is a high frequency of cycles and the initial volume of the bellows is smaller. For this reason, we used a smaller bucket in the second prototype.

After fixing all of the problems we found in the bellows, we tested the pressure again and reached 202 mm Hg when pumping with our hands and using all of our strength. This is significantly closer to the Medela value, but we now have the problem of generating too strong a vacuum, causing greater exhaustion when using the device. We need to find a happy medium between pressure and ease of use so our pump does not tire mothers too much. Another problem we face in our second prototype is the mobility of the bucket – it has a lot of freedom to wiggle when pumping. This makes using the device more difficult than it should be as well. We will address these issues in our third and final prototype of the summer next week.

After all of the hard work of the week, we wanted to have some fun on the weekend so we organized a group trip to the zoo! Harrison, Whitney, Florence, James and I went to the zoo Sunday afternoon and had a great time! It was extremely hot and sunny, but that did not stop us from looking at many exotic birds and monkeys. We also saw lions, turtles, strange looking pigs with curvy tusks, flamingos, and cheetahs, among other animals. However, the highlight of my trip to the zoo was Florence’s face when she saw the sea lions. When we were approaching their enclosure, I learned that they had never seen sea lions before – they thought it would be a regular lion’s enclosure, so you can imagine Florence and James’ surprise when a large amphibious mammal appeared and began swimming about. It would swim in circles, then pop out of the water near these children like it was playing with them. This was pretty adorable, but Florence’s elation at how freaking cute this creature was managed to be even more adorable.

As if this wasn’t enough, it then got better! The trainer came out to feed the sea lion, meaning that we got to see it perform tricks. The sea lion jumped out of the water onto a platform and posed. It also twirled around in the water and was generally adorable. When I talked to Florence the next day, I learned that she re-watched the videos she took of the sea lion multiple times that night. I am so glad that I got to share this experience with them and help them create lasting memories.