Tungsten needle for diatom manipulation.

What equipment do you use? Post pictures and descriptions of your microscope(s) here!
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Phill Brown
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Tungsten needle for diatom manipulation.

#1 Post by Phill Brown » Tue Jun 01, 2021 9:55 am

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Hi. Did a search here but didn't find so better to have twice than not at all. Klaus Kemp YouTube video "The diatomist" shows a diatom being picked up, the tip of the needle is most likely a tungsten. The method for making is quick, easy and repeatable.Image
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.25mm tungsten wire from eBay. 10% caustic soda. The carbon rod is the inside of cheap carbon 1.5v battery. 7v AC straight off a transformer. Place 10mm in the dip for 1 minute, the tip 1-2mm can be erroded more than the image but just to give an Idea. Doesn't work with DC voltage. Maybe lower power and lower concentration of caustic give better control. 5 minutes and the wire is gone.
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MichaelG.
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Re: Tungsten needle for diatom manipulation.

#2 Post by MichaelG. » Tue Jun 01, 2021 11:35 am

.

Nice work, Phill

I have tried the molten Sodium Nitrite method with reasonable results ... but yours looks superb.

MichaelG.
.
Edit: __ from my notes:
This appears to be the original description of the electrolytic method:
https://europepmc.org/backend/ptpmcrend ... obtype=pdf
... and a video about using the Sodium Nitrite stick:
https://youtu.be/WvepYAwiKU8

Edit: as a courtesy, changed Phil to Phill
Last edited by MichaelG. on Tue Jun 01, 2021 7:47 pm, edited 2 times in total.
Too many 'projects'

Phill Brown
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Location: Devon UK.

Re: Tungsten needle for diatom manipulation.

#3 Post by Phill Brown » Tue Jun 01, 2021 12:02 pm

Used a small slide to avoid shorting. Think it's hydrogen given off but there is a fine mist of caustic given off too.
The .25mm tapers to a fine point just by leaving 10mm in the solution. tip can be made sharp to a molecular level apparently by practice dipping the tip. Bends rather than breaks.
Transformer is from a sewing machine controller,6v AC winding for the light.
A microscope 6v AC light supply should be ideal.
Thin wire to start is better, tried .8mm and didn't get good results, not that it wouldn't work but I don't have enough spare time for another research project.

viktor j nilsson
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Re: Tungsten needle for diatom manipulation.

#4 Post by viktor j nilsson » Tue Jun 01, 2021 12:10 pm

It's a very cool technique. There were a couple threads on the on photomacrography forum a while ago, with some very nice images:

https://www.photomacrography.net/forum/ ... hp?t=41452

https://www.photomacrography.net/forum/ ... p?p=260845

Hobbyst46
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Re: Tungsten needle for diatom manipulation.

#5 Post by Hobbyst46 » Tue Jun 01, 2021 12:44 pm

This thesis, from 2013

"Fabrication of Tungsten Tips Suitable for Scanning Probe Microscopy by Electrochemical Etching Methods"
Gobind Basnet
University of Arkansas, Fayettevill

Shows the etching of a 0.25mm tungsten wire in detail, using alkaline solution and electrolysis. Although his cathode was made of copper and power was DC , not AC. He produced long and sharp tips at 6.5 Volts and 4mA, 30 minutes etching per tip.

My used acupuncture needle is made of stainless steel (I guess) and is ~0.18mm thick. Can be had free from acupuncurists. Can probably be etched similarly, maybe using acid instead of alkali. Yet it is probably mechanically inferior than tungsten.

The question is, do diatoms adhere to the pointed tips better than to thin glass rods ?

Phill Brown
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Re: Tungsten needle for diatom manipulation.

#6 Post by Phill Brown » Tue Jun 01, 2021 1:32 pm

The short film The diatomist is worth watching on YouTube. Klaus Kemp uses a needle that has tip erroded. Tungsten .25mm is cheap for 10m. Make a lifetime of needles from that.
Seen someone selling them ready made $9 for 3.

Charles
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Re: Tungsten needle for diatom manipulation.

#7 Post by Charles » Tue Jun 01, 2021 1:51 pm

I have never used tungsten needles. My only concern would be if the tungsten needle may have less give/flex than the glass needle and more apt to damage a diatom frustule than a glass needle? I would have to try and see. Also glass 'erodes' whereas tungsten would not.

I believe Klaus Kemp used glass pulled needles. He may have tried other things but I think the glass needle was his primary. If you look at the needle in the shot which shows his setup, you can see the glint the glass needle makes.

In this video, the needle looks dark but it also is a pulled glass needle.
https://www.youtube.com/watch?v=g-F0Id_m3Ys

Phill Brown
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Re: Tungsten needle for diatom manipulation.

#8 Post by Phill Brown » Tue Jun 01, 2021 3:08 pm

Hi Charles, Your work and posts here are much of my inspiration.
The bright point Klaus says is the diatom he picked up?, Glass may well be the way to go, I found tungsten easily doable which moves it up the list above glass so far.
Pure tungsten withstands the tip bending like a dog's leg.
Tungsten carbide is very brittle and hard like glass.
I use down to .1mm TC micro drills,I can resharpen .2mm drills but they break easily.
Pure tungsten can easily be cut with wire cutters but I have a Dremel with small diamond disc. I expected it to be brittle but it's not in that way. Will break up on cutting, feathering at the end but easily ground flat. Conducts heat very quickly when grinding. These are only my findings and may cut time off anyone having a go.

Hobbyst46
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Re: Tungsten needle for diatom manipulation.

#9 Post by Hobbyst46 » Tue Jun 01, 2021 3:46 pm

To catch a diatom, one relies on eletrostatic forces, due to electrostatic charges on the needle point.
For this to work, the needle should be made of an insulating rather than a conducting material. Hence glass, rather than metal.
That is perhaps an extreme statement, a fine point tends to accumulate charges, so perhaps even with a metallic point the diatoms attach.
Picking and transferring a diatom involves the balance of electrostatic attractions:
just enough adherence to attach the diatom to the pointed needle, overcome its attachment energy to the keeper slide, then overcome gravity so it can be moved in air like a building block on a construction crane, then sufficiently weak adherence to let the diatom detach from the pointed needle and attach onto its new location.

In practice, diatoms will attach to various "fingers": animals eye lashes, brush hairs, acupuncture needles...
Some of us use brush fibers, pointed glass capillaries, I use 6-10 micrometer thick blunt glass fibers, and I wonder if anyone has tried metallic points.

Phill Brown
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Re: Tungsten needle for diatom manipulation.

#10 Post by Phill Brown » Tue Jun 01, 2021 5:08 pm

Thanks for sharing your experiences and insights.
Glass seems to be optimal.
It is probably best I don't make glass needles if possible,glass splinters can be hard to remove.
If someone chimes in with "Tried tungsten, doesn't work for diatoms" that would be good too.
For fine pointed needles tungsten is quite forgiving relative to glass.

MicroBob
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Re: Tungsten needle for diatom manipulation.

#11 Post by MicroBob » Tue Jun 01, 2021 5:30 pm

Hi together,
tungsten carbide has some very special properties, one of them is a very high e modulus which makes it very stiff at a given section. In diamtom picking I can imagine that this can be an advantage. I used baby seal hairs for this and they are very flexible and tend to snip a frustule away when stored energy is set free. I used a little skin fat to make the tip adhesive, as far as I know this was Möllers method too. One should be careful with these needles, they probably enter into skin easily and might snap somewhere inside.

Bob

Phill Brown
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Re: Tungsten needle for diatom manipulation.

#12 Post by Phill Brown » Tue Jun 01, 2021 8:34 pm

Hi Bob, Using only pure 99.9 .25mm tungsten for this exercise.
Very cost effective per needle.
I can freehand move pollen or pick a dust particle from a slide with them.
Tungsten carbide is a very different material, never rewards being flexed.
Pure tungsten wire can surprisingly be bent to 90° without breaking if it's thin enough. Glass fragments are notoriously difficult to find and remove.
So far not found anything to say tungsten is toxic or hazardous but every day's a school day.

Hobbyst46
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Re: Tungsten needle for diatom manipulation.

#13 Post by Hobbyst46 » Wed Jun 02, 2021 8:07 am

One more point (pun) about strength and flexibility. Glass in general is fragile and sturdy. However, A glass fiber of diameter of the order of 10 um and ~2mm length is flexible. It can be bent to almost a right-angle without breaking. So it serves as a lever, fishing pole, crane, and pushing rod altogether. Would be better if the tip could be sharper and tapered, but to make it such we need some sophisticated heating and pulling.

Phill Brown
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Re: Tungsten needle for diatom manipulation.

#14 Post by Phill Brown » Wed Jun 02, 2021 8:51 am

Image I'm no Uri Geller. Maybe a useful tool. Not advocating it's use over plastic,glass or a hair pulled out of a hat.
Turned the tip with brass tweezers.
Easy to put a hook or bend that may have an application that is not as easy to achieve with glass.
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Phill Brown
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Re: Tungsten needle for diatom manipulation.

#15 Post by Phill Brown » Wed Jun 02, 2021 9:17 am

With the tip in the vertical plane it would be a different tool.
Attraction at this scale is easier to experiment with than predict. Dismissing it is the easiest option.
Particles seem to prefer sticking to the tungsten than glass which may prove an issue that can or cannot be overcome.

Phill Brown
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Re: Tungsten needle for diatom manipulation.

#16 Post by Phill Brown » Wed Jun 02, 2021 9:43 am

Melting point is high, would withstand being dipped into molten glass, which may well stick and pull a finer tip.
Not something I am likely to get round to but may combine properties of glass and tungsten.
Someone somewhere has likely already done it, patented the method and as many applications as they could come up with in their bubble bath. Most importantly should be fun or best left to someone who enjoys it.

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