User:Brian P. Josey/Notebook/2010/06/25

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Magnetization of Objective

I'm looking into the possibility that the objective is magnetized. For a couple of my experiments, the droplets have been moving, but not in the direction that I think they should, or away from the magnet and not towards it. Koch pointed out that the objective, which I know can be magnetized, could have its own magnetic field from being so close to the other magnet all the time. I want to check this and either rule out the possibility, or figure a way around it. To do so, I am doing two more experiments on the microscope with the ferritin, and possibly a third. The first, I am just filming the emulsion for 15 mins, and I'm going to check it to see if it is undergoing Brownian motion, or if there is a force pulling all of the ferritin in one direction. Then I'm going to repeat that with the magnet directly to the top of the image to see if it does anything to the ferritin. If it turns out that in both cases the ferritin is moving towards the magnet, or where it would be otherwise, then I am going to do a third experiment with the magnet in a different position. Then if necessary I will start building a model of the objective and magnet in FEMM to measure the force, and see if moving the objective away, or using different slides would change it any.


I was able to film the case both with and without the magnet. In both cases it is over fifteen minutes, at 1 fps, and played back at 60 fps over 15 seconds. Without the magnet:

With the magnet, just outside of the field of view to the top of the image:

Steve Koch 23:12, 25 June 2010 (EDT): Agree, see tons of drift in top image and little in the bottom. Will be interesting to see non-ferritin results. In any case, force is tiny, right?
Brian P. Josey 18:20, 28 June 2010 (EDT) The force should be incredibly tiny, and I'm going to check it in FEMM if I can find the dimensions on the objective.

It appears that the ferritin is drifting off to the left in the first video, which could be the result of magnitization, or a thermal drift. To check to see if it is a thermal drift, then a regular emulsion, without the ferritin would also move in one direction. To check this, I am creating a new emulsion of water suspended in oil. The ingredients are in order:

  1. 1 μL DI water
  2. 0.1 μL Tween 20
  3. 98.1 μL mineral oil.

This creates a 1:100 emulsion of water in oil.

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