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View Full Version : Who needs macro lens when you've got a Scanning Electron Microscope (SEM)


425nm
03-22-2013, 07:05 AM
So sadly one of my emerald crabs passed away...so I ran him through the Scanning Electron Microscope at school. Morbid but really really cool.

What is a Scanning Electron Microscope you ask? Well it's exactly what its name suggests. It's a microscope which uses electrons instead of photons (light particles) to image things. Electrons being much smaller than photons of visible light provide much better resolution.
To get an image, the SEM fires electrons at the sample then detects electrons that bounce off the sample as well as those that are not.

Here's what the microscope (the scope belongs to the University of Alberta's Microscopy unit) itself looks like:
http://i22.photobucket.com/albums/b311/Amemaru/2013-03-05142157_zps42fc4e80.jpg

Now, inorder to good good quality images on an SEM samples must first be coated in either gold or a gold-palladium mix. To do this we use this machine, a sputter coater:
http://i22.photobucket.com/albums/b311/Amemaru/2013-03-05142131_zps5b6224d1.jpg

The little metal discs you see on the table are called stubs, they're essentially frag plugs for SEM specimens. You mount your specimen to your stub then you slot the stub onto disc. The disc rotates to ensure complete coverage of your specimen.
There are a few reasons we coat specimens:

1) To ensure uniform conduction of electricity.
2) To prevent charging (bright spots on the image due to differential electron absorbance/release)
Both of these are due to specimens being made up of many many different molecules/compounds etc. These will all react differently to being bombarded with electrons. The gold coating prevents solves these by providing a uniform surface.

Gold's high electron density makes it a good choice for combating these two problems.

Gold-palladium coated crab:
http://i22.photobucket.com/albums/b311/Amemaru/2013-03-05142146_zpsd7e17218.jpg

Finally, the actual images themselves. Now since the crab is so very big relative to what SEMs are normally used to look at these are actually super duper up close shots of his exoskeleton (and the things living on it!)

http://i22.photobucket.com/albums/b311/Amemaru/Science/EmeraldCrabHitchhiker_zps5acf7480.jpg

http://i22.photobucket.com/albums/b311/Amemaru/Science/EmeraldCrabHitchhiker2_zps84c4b9f9.jpg

Eyeball:
http://i22.photobucket.com/albums/b311/Amemaru/Science/EmeraldCrabHitchhiker4_zpsb5034800.jpg

Leg bristles:
http://i22.photobucket.com/albums/b311/Amemaru/Science/EmeraldCrabHitchhiker3_zps36522d2e.jpg

Stayed tuned! In a few weeks I'll have histology slides of pink birdsnest!

Now I got to take these images as part of a class (Zoology 450 - Evolution of Form and Function, if anyone is interested). Actually running the SEM costs somewhere in the range of $300/hr plus some amount for the sputter coater (I'll double check the price tomorrow).

Please see wikipedia for a more through explanation of SEM:
https://en.wikipedia.org/wiki/Scanning_electron_microscope#Resolution_of_the_SEM

Jakegr
03-22-2013, 07:28 AM
That is so cool. Thanks for sharing.

kien
03-22-2013, 12:39 PM
Whoa!! That is awesome! If I had access to one of those I'd be pulling random stuff out of my tank to scan LOL.

fixerupper
03-22-2013, 12:55 PM
To cool. Used one 'back in the day' at the U of S. They kept everything under lock and key as would be expected. If memory serves me correctly, the coating process was almost as exciting. The whole chamber glowed an eerie magenta colour. Thanks for sharing. Good luck with the class and have fun!

FishyFishy!
03-22-2013, 02:12 PM
Awesome!! haha

lastlight
03-22-2013, 03:23 PM
That's unreal thanks for the thorough rundown !

Delphinus
03-22-2013, 03:50 PM
Had there been a little Tiki head next to the pineapple looking thingy I'd be worried about Spongebob and Squidward!! Haha.

These pictures are awesome, thanks for sharing!!

That microscopic vermetid is mind blowing. Man they get into everything!!

pinkreef
03-22-2013, 04:02 PM
thanks for sharing that :biggrin:

ScubaSteve
03-22-2013, 05:12 PM
Ha! Awesome stuff! I'm glad to see I'm not the only one around here that plays with these things. I'm actually walking over for 3 solid hours of SEM as I type this.

I love adding extra fun things in with my samples just to see what they look like. Once I get a patent filing in on one of my processes I'll post up some pics of a few nano-objects I made.

Are you able to drop the working distance to 20-25mm? It'll probably give you a bit more breathing room to to see more of the crab. I've always been curious to see the mouth parts in greater detail.

hillegom
03-22-2013, 06:14 PM
very interesting indeed.
Thanks for sharing

425nm
03-22-2013, 08:19 PM
I could spend all day pulling pumping things out of tank and throwing them under any kind of scope. I really want a dissecting scope for home, the old ones that get given away are always snatched up by the graduate students.
Are you using the nano tech institutes SEM?

Good luck with you patent application, those things are some serious paper work.

We were able to get a larger working distance but not high enough to get a complete shot of the crab, mainly just larger swaths of the carapace. It was more interesting to get higher mag shots. We did also try to get a shot of the mouth parts but sadly we just couldn't get at it (mounting wasn't quite right, that's what I get for getting someone else to do the mounting for me. Should hqve just skipped my biochem class).

I'll have some histology images of birdsnest in about a week I'll post. Just did a trichrome stain on some of them. Turned out fantastic. Sadly I don't have enough time left in the term to do any fluorosecence/confocal.
Ha! Awesome stuff! I'm glad to see I'm not the only one around here that plays with these things. I'm actually walking over for 3 solid hours of SEM as I type this.

I love adding extra fun things in with my samples just to see what they look like. Once I get a patent filing in on one of my processes I'll post up some pics of a few nano-objects I made.

Are you able to drop the working distance to 20-25mm? It'll probably give you a bit more breathing room to to see more of the crab. I've always been curious to see the mouth parts in greater detail.

Ian
03-22-2013, 10:57 PM
AWESOME!!!!!!!!!!!!
makes me want to go retake my SEM course judt to play with the big toys

Cymaster007
04-11-2013, 07:13 PM
Very cool! Thanks for sharing! Get a bristle worm under there next!

kent
09-09-2013, 12:27 AM
WOW.would love to see a bristle worm as well !

Myka
09-09-2013, 12:46 AM
Awesome, thanks for sharing!