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The precision limit of the mechanical stage is on the order of 1um. The limit to that is likely in the bearings of the translation stages (friction in the balls rolling, and not perfect spherical balls), but the motors are not going to be better than that anyway. Then if you had a way to control the force on the tip with great precision (perhaps mount on a cantilever and measure beam deflection like an AFM), you could do mechanical lithography with a <100nm tip. However, I do not think this is well suited for something like that. An AFM can be used to perform mechanical lithography, and works at length scales ~100nm. For sub-micron movements, piezos are king.

@@BairdBanko hint for you, if you like to meassure deflection of your tip, you need 2 magnets and a piezo disk, apply ac to the piezo disc holding 1 magnet and move it over the tip where there is the other magnet then you can meassure current changes contactless on the piezo (this gives you nanometer precision as it gets closer to the magnetic force). for the stage use compliant mechanism, where you dont depend on any bearings and additionally save money as you dont need the precision stage anymore. I might have to try that... love your project congratulation.

glad to be of help! Doing spin polarized?

It is a machine that scratches Hall bar patterns on thin film samples. Good for making electron transport measurements on samples where the mean free path of an electron is on the order of 1000um. Smaller Hall bars are made with photolithography, which is quite expensive to perform on every sample.

Oh so not for making designer acid tabs then....

Hi, for tips larger than 2um, mechanical sharpening is preferred. If you want a 1um tip for microprobe stations, there are companies that sell those somewhat cheap (Signatone is one). Additionally, you make want to use thicker wire for a microprobe, I have not tried etching thicker wire, that may be an interesting test. Someone inquired to me about an electronics BOM, I will be posting that in a few days. Cheers!

Yeah, shoot me an email at bdb5454@psu.edu

The oil layer would also have a meniscus, perhaps less, but still present. I actually tried putting dish soap in the aqueous NaOH etching solution, to try and break the surface tension for the sake of curiosity. However, it did not reduce the meniscus significantly. Honestly, having the meniscus is not an issue, and if you wanted a very short, sharp tip, it might also work to ramp the wire out of the etchant during the etch. This is something I have not tried, but I imagine you could program it to make any arbitrary tip length.

oil would prevent evap though, I think, which could probably help control the etch rate

@@ntm787 Oil would prevent evaporation, that's an interesting idea certainly! But over the course of 8 min or so that an etch takes, there is no significant evaporation, indicated by the lack of terracing. The tip with terracing was produced because I intentionally broke the meniscus by hitting my hand on the table. But to test if evaporation was happening to a significant degree, I did try putting some Cling Wrap on the dish, and then when the wire plunged into the etchant, it poked a small hole in the wrap. However, I did not see any differences between these tips, and when I did not include the Cling Wrap (under an optical microscope).

​@@BairdBanko I'll be honest, I only skipped through the video without audio. I'll watch it in full later on tonight! Nice work overall :)

@@ntm787 No problem! I did not talk about that in the video anyway. Cheers!

Wow never thought I would have @BreakingTaps comment on a video of mine! Maybe I have to make some more videos about the STM. Expect another video by the end of the year :)

TH-cam is extremely good at getting people content they are interested in because Google has most people's search history so this isn't surprising lol.

@@BairdBanko Can't wait to see it! Your initial results look fantastic already 🤩

Fancy meeting you here !