Recent content by canuck123

Update: I built a new microscope stage and new coils much like the ones in that paper (but a little improved). Everything works a treat. The cores are just mild steel and they have the same angle on the end as the objective so they can get in as close as possible to the sample. I put a mild...

20x is the right size to be able to see my particles. Gives roughly a 500 micron square view which provides a good sample size to see how homogenous my particle movement is. Yes, the current fluid cells are complicated and somewhat large, but I am working on dumbing it down and making it smaller...

I am using a zeiss 20x water immersion objective, I believe this is the one: https://www.micro-shop.zeiss.com/en/us/shop/objectives/421452-9800-000/Objective-W-Plan-Apochromat-20x-1.0-DIC-M27-75mm They are quite expensive and have quite a small working distance from the sample so they have to...

I am certainly feeling the stupidity now. I know programs like COMSOL would be good but those licenses are like 4000$ or something. I initially wanted to make the exact same setup as pictured in the research paper, but my microscope objective is so frickin wide that I can't get a coil close to...

Thank you. By saying super high permeability doesn't matter, does that mean mild steel would be good enough? Does the coil have to be super close to the sample, or does the core just have to extend super close?

I tested with DC and the air core value was again as expected, but the iron core strength was much lower than expected. Yes the dimensions are weird, I was trying to make it fit with my microscope objective and available fluid cells, since it is a pretty big objective and the fluid cell is...

I see, I had not considered that the border around them was the same stuff. They simply stated that the cores were pure ARMCO iron.

Here is the link to the supplementary information from the paper, this has all the important stuff about the setup: https://www.rsc.org/suppdata/c5/lc/c5lc00294j/c5lc00294j1.pdf

Oh I see. Here's a picture of the setup from the study I am trying to recreate. Do you know why this setup of winding directly around a solid iron bar would have worked for them?

When you say the core should be laminated, are you saying the kind of thin laminates that you find in a transformer to reduce eddy currents? Or that the core should be encased in something non-conductive? Becasue in that case the delrin bobbin would solve both problems

Oh. So even if I wound directly around the iron core, it would be bad? I thought winding directly around a core was pretty common, I have seen it done in many places, including the study I am trying to recreate. Why would an insulated matrix of powder be better than a solid iron core? Sorry...

Sorry, I guess I don't really understand the problem with the aluminum. I could make it instead with delrin (plastic). Frequencies are 10-20Hz, so pretty low. Are you saying I shouldn't have a bobbin, and just wind directly around the core? Is the 1mm wall thickness of bobbin creating a big...

I'm not sure I understand. Why would it short the coil if the wire is enameled? an induced field? Sorry if this is stupid, I guess I just need to learn more. I was able to generate the exact expected field strength with an air core, is this expected even if the bobbin is a problem?

Sorry I shouldn't have said uniform, the field shape is not uniform, I simply meant that in each axis, the field would be uniform radially from the center. Each axis of coils are producing different field strengths and frequencies, so the sum field shape is not uniform. The idea is that this...

I shouldn't have said uniform. Not each pair of coils will be producing the same field. There will be an eliptical AC rotating field produced by the Z and y axis coils (90 degrees out of phase at function generator), and a weaker AC field applied through the x pair of coils. I've attached an...