Week 7 - Well Design

While our testings with the K'nex electrospinner seem to be doing quite, we've realized that the well holding the polymers we are testing is not the most ideal shape. The height of the well just reached the spindles on the gear and the area of 64 square centimeters resulted in more polymer to be tested than necessary. Because of the flat shape, when polymer was poured in, it would fill the entire bottom before actually reaching the spindles on the gears. This caused a large percent of our polymer solutions to become a waste as they were no way near spindles. It takes time and money to create polymer solutions; therefore it was necessary to create a new well that would require the least amount of polymer to be used as possible.

New Well Design

This new well design has a cylindrical shape in order to fit with the electrospinner's gears. It also reduces that amount of polymer needed to reach the spindles. There is a small rod projecting out of one side of the well that will allow the copper wire to feed into the solution. This was, the electrical current can run through the solution and the copper wire is not as exposed as it used to be, reducing the likelihood of someone getting shocked. The rod was placed at a raised angle so as to not allow the solution to flow out of the well. All that remains now is to wait for the well to be 3D-printed and test it out. Hopefully all this well won't react with the solution and we can continue electrospinning.

*The well design was created by Travis Weiss

Week 6 Progress

Ultimately, our goal is to create a sample of nanofiber that is capable of being used in a capacitor. Unfortunately, we ran into a few complications in the past week. Our initial test-run had been spun using PEO; however, in order to obtain a sample that could be calcified, and thus used in a capacitor, we needed to spin a sample using PAN (Poly-Acrylic Nitrile).

Today, during a PAN trial, instead of collecting a usable sample, we obtained a spider web type of structure that extended from the collector plate down. Upon consulting with Dr. Kalra, it was determined that the most likely cause for this was the moisture in the air. Apparently, when the air contains too much moisture, the gaseous water particles interfere with the electric field that directs the nanofiber jet to the collection plate. Using a meter, we determined that the air has a humidity percentage of 48%. To cope with this, we injected pure oxygen into an enclosed box to drive the moisture out of the air. When the box reached only 20% moisture, we ran the spinner again, however, the sample didn’t spin as it should have. At this point, the sample of PAN and DMF had become a gelatinous solid because so much DMF had evaporated out of the solution. It takes a full day to properly stir a solution, so that concluded this week’s tests. 

Week 5 Results

During lab on May 2, the group began our first actual trail on the electrospinner. This time we had ample time for nanofibers to form. For this test, we once again used the PEO polymer, however, this one dated more recently to April 27, 2012. All other variables to the electrospinner remained the same, with the gears being seven centimeters apart and a total of 12 strings attached to the gears, with the exception of the shiny side of the aluminum foil facing upwards, away from the gears. 


While this trail was successful, we decided we needed to better optimize the tray holding the PEO so we would not need to pour as much polymer. Not only do we want to make the tray smaller, but we also want to the tray to be closer to the gears. This will allow less polymer to be used, as well as, attach to the strings of the gears faster. 


If you observe the attached video, you can see the nanofibers begin to form and attach to the foil. The sharp white lines that show occasionally are the nanofibers. 

Once we were able to attain nanofibers, we took a sample down to our advisor's lab to view it under a high-powered microscope. The resulting images (shown below) displays a magnified view of what our first batch of nanofibers actually look like!

 

Week 4 Results

During lab on April 25, the group began our first tests on the electrospinner. Unfortunately, due to problems with strings attached to the gears, we were only able to have the electrospinner run for about 10 to 15 minutes. Initially the original width between the gears was greater than the pan holding the polymer, meaning we were required to restitch the strings on the gears twice. The second time, the strings would not stay attached to the gear, meaning I had to consistently restring the gears. Due to this time constraint, it gave little time for nanofibers to form that would be noticeable.

For this test, we used a polymer provided to us by our advisor of five weight percent PEO H₂O SSA (with no salt) dating back to February 16, 2012. The gears were separated seven centimeters apart from the inside of each gear and with a total of 12 strings able to hold the polymer droplets. The aluminum foil was place above the gears, with the shinier part of the foil facing down towards the gears and polymer. Inside the aluminum foil was a sheet of copper mesh that assisted in collecting nanofibers. If you look closely you can see droplets of polymer attached to the strings. However, the sheerness of the polymer would make it difficult to see any nanofibers heading for the aluminum and with time constraints, there is little chance any nanofibers can be seen on the aluminum by the naked eye.