Day 2

Yesterday, I continued working on the hydrogel layer-by-layer assembly system I had created last time by adding two bilayers, measuring the thickness, adding two more bilayers, and measuring the thickness again, all with the goal of being able to eventually chart the growth regime. Before I could actually add the bilayers, though, I had to replenish the necessary solutions and solvent mixes, which involved some fun times with a giant jug of methanol.

The actual addition of the bilayers is a somewhat annoying process because it entails rotating the silicon wafers throughout sectors of a petri dish and rinsing them off in between. In theory, each wafer should only be in each sector for exactly ten minutes because some grad student no longer there once told another grad student no longer there who then mentioned in passing to someone who informed the undergrad I work with who in turn told me that ten minutes is the ideal time. In practice, each wafer is there for anywhere between eight and eighteen minutes. One of the grad students did tell me, however, that in Russia they once had to make 24-bilayer wafers using this same method, so I was grateful that I only needed to add a total of 4 for now. 

During the waiting periods, I helped out with a lot of random tasks, like measuring thicknesses of another wafer system, playing with Excel sheets, and learning to use the contact angle machine. This last item was particularly cool for me because whenever I had done contact angle measurements at school, we used an especially unsophisticated method that involved magnifying the droplet and measuring, by hand, with a protractor. This machine was much cooler because a needle was used to precisely deposit the droplet and then the software measured the contact angle for you.

I then measured the thicknesses of my own wafers using the ellipsometer - this fickle piece of equipment and I are becoming fast friends, although I have to say it's a bit of a complicated love-hate relationship at times - and discovered that my data makes no sense. Things that should have grown chose to shrink, and vice versa, which means I'll have some more fun times attempting to figure out why this should happen in general and why this should happen to me, specifically.

Day 1

Today was my first day at internship, and I was surprised at how much work there is already and how fast time went. I'm working with an undergraduate student on a project concerning the deposition of a hydrogel over a prime layer (consisting of particular bilayers) on top of a silicon wafer, and specifically, I'll be studying the growth regime of one such system. Since today was my first day, I was led through some practice of creating these depositions for the system I'm working with and running measurements on them.

I started with the very beginning of the process - cleaning the wafers - and then ran through all the steps needed to coat them with the various polymers. Along the way, I remade a solution of phosphate buffer and stabilized the pH of various stock solutions; since the film on the wafer responds to pH, it's important that the levels are exactly where they should be. 

After I deposited the prime layer on the wafers, I was taught to use the ellipsometer to measure the resulting thickness. At first, I was utterly confused as to how to operate the machine, but going through the steps the approximately one million times needed to do all the measurements, I was basically doing it without even having to think about it. This piece of equipment is very old and fickle, so it only worked when it felt like it, leaving many of us in the lab disgruntled. 

Then I soaked the wafers in a certain acid and brought them over again to determine the new thicknesses. During the down time in this process, I worked on a set of wafers under a variation of my system and removed a particular polymer from their prime layers by exposing them to a higher pH. These also had to be measured in the ellipsometer.