External Deliverables

Test design that never reached realization because of cell constraints.

Literature review on viability of Wasatch Designs using different methods of turbulent flow

Full review of the viability of the current printhead and the new design proposed.

Internal Deliverables

  • 10 Degree Slant Wasatch Design

  • 20 Degree Slant Wasatch Design

  • 18 Degree Cone Wasatch Design

This is the Fluid splitter that I designed in order to be able to pump one tube with a peristaltic pump with a secondary tube port for secondary fluid. Leur barbs for tubing can also screw into each bottom port

Difficulties This Semester

This semester, I learned more about failure than success. Many things didn't really pan out due to a variety of factors. Our cell cultures were not growing at a usable rate, and since we had to revert to an older passage number initially due to the winter break, the cells also didn't seem to agregate. This definitely slowed down any progress that could be made as far as culture experiments went. I had designed an environment in which we would be able to flow cell media through our printhead and flow waste out, theoretically, but it wasn't able to be tested because the cells were not growing well enough or clumping together enough to be distributed into the well molds. I didn't want to flow straight media through there as it would only test the seals on the environment, and wouldn't actually test viability for the expense that our cell growth media was.

In the area of simulation, the intent was to take the code that one of John-Luke's professors had developed for particles in fluid application, and revamp it so it is actually usable and user friendly. After a few attempts at contact, it seemed as though she wouldn't share any specifics in the code, and was even wary about letting me take the code in general to figure it out myself. I found the base program that she was working with which was called OpenFoam. This was difficult to set up, and because of time constraints, I didn't have a chance to properly learn it. Instead, I simulated different flow architectures in COMSOL negating the particles inside the fluid. What I was attempting to discern from this was whether it is viable to attempt vortex creation inside of the wells with our current printhead. This will be continued in the simulation paper to the left

Conclusion

I have learned a lot this semester even if many things have taken a different direction than I originally thought. This semester has been filled with learning microfluidic flow equations and principles as well as learning from failure. I wanted to capture a few last learning points that relate to my objectives.

I learned about the permeability of PDMS and how it works with CO2 exchange. According to the literature I have found, PDMS CO2 and O2 permeability depends on thickness and air bubbles. Most research on the topic is done with as little air bubbles as possible which luckily, is what we want to maximize transparency for MicroPIV experiments. It seems as though in a 50 micrometer by 50 micrometer channel, the PDMS can only be about 500 micrometers thick. This barely supplies enough oxygen to keep the fluid at an appropriate supply for in-vitro experiments. Because of this, in a test environment, there would have to be a separate method for Oxygen and Carbon Dioxide exchange such as media supply gas filters.

One of the best parts of the semester, and one that I learned much from was the Medical lab series hosted by Dr. Jensen. I have always wanted to learn suturing as I am an avid backpacker, and learning how to suture could save someone's life when there are no medical professionals available. We got to travel to the Medical Education Lab at the Fargo VA Hospital for an afternoon too. It was very fun and informative to learn the different techniques that medical students use to practice for real world surgeries. In addition, we got to tour the body of a cadaver and see almost all of the major organs in person. This was extremely interesting as we got to see how smoking and lung cancer actually affects lungs, look at irregularities in the bowel, and learned how to perform a Tracheotomy.