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Home-Built Scanning Tunneling Microscope (2015)
- kurthr 6y agoCA3140 OpAmps also work well. The comments about 1pF feedback do speak to one of the challenges with feedback stability, where stray capacitance on the proto-board may or may not be present.
- analog31 6y agoIndeed, a 100-Meg feedback resistor is mostly a capacitor. You could think of it as an integrator with DC bias control. This is probably the best article I've seen about transimpedance amplifiers: https://electrooptical.net/static/oldsite/www/frontends/frontends.pdf https://electrooptical.net/static/oldsite/www/frontends/fron...
- jacquesm 6y agoYou could draw a pretty interesting graph of how the resistance/parasitic capacitance relationship governs which component is dominant at the high end of the resistance range.
- prennert 6y agoHis day-job is pretty mind-blowing, too. He basically works on combing DNA, by squashing it "into nanogrooves [that] are less than 50 nm" https://dberard.com/research/ https://dberard.com/research/ edit: added description of his work
- amelius 6y agoCan you image non-conductive surfaces with this technique?
- smitty1110 6y agoNope, the technique for that is an Atomic Force Microscopy[1]. 1: https://en.wikipedia.org/wiki/Atomic_force_microscopy https://en.wikipedia.org/wiki/Atomic_force_microscopy
- alted 6y agoAnd it turns out DIY atomic force microscopes are possible too! (e.g., [1]) It's probably less likely to get all the way to atomic resolution (0.01nm) like a scanning tunneling microscope, but atomic force microscopes can take many types of 1-to-1000nm-scale measurements and are often more practically useful. [1] https://hackaday.com/2014/04/29/a-diy-atomic-force-microscope/ https://hackaday.com/2014/04/29/a-diy-atomic-force-microscop...
- waiquoo 6y agoOR helium ion microscopy, but that is not as widely available afaik 1: https://en.wikipedia.org/wiki/Scanning_helium_ion_microscope https://en.wikipedia.org/wiki/Scanning_helium_ion_microscope
- ortusdux 6y agoBest you can do is gold plate the object you would like to scan. Sputter coating is the preferred method. https://en.wikipedia.org/wiki/Scanning_electron_microscope#Sample_preparation https://en.wikipedia.org/wiki/Scanning_electron_microscope#S...
- oasisbob 6y agoThat's for SEM. I've never heard of sputter coating used for STM.
- ortusdux 6y agoYou are right, I got those two methods mixed up. It looks like gold sputter coating would be a good solution for the home made tungsten STM tips mentioned in the link.
- Retric 6y agoThat’s a SEM which is significantly lower resolution, but lets you zoom in and out across a huge range. STM on the other hand is for looking at individual atoms so coating a surface is just going to show that coating. https://en.wikipedia.org/wiki/Scanning_tunneling_microscope https://en.wikipedia.org/wiki/Scanning_tunneling_microscope
- oasisbob 6y agoSort of? STM is frequently used to characterize adsorbed molecular monolayers on a graphite substrate. You're obviously depending on electron conduction to image the sample, but you can image all sorts of things which wouldn't be considered conductive as a bulk material.
- twobitshifter 6y agoBen Krasnow built his electron scanning microscope back in 2011. I never expected to see that one upped. https://benkrasnow.blogspot.com/2011/03/diy-scanning-electron-microscope.html?m=1 https://benkrasnow.blogspot.com/2011/03/diy-scanning-electro...
- oasisbob 6y agoHomebrew STM is a pretty common and simple in principle. I used to have a chemistry prof who would guide a group of high schoolers through building an STM head each year. Homebrew SEM is probably much more difficult and rare.
- _Microft 6y agoThe scanning electron microscope project seems far more involved than this one. I submitted the SEM before this one by the way but it unfortunately did not catch on.
- lappa 6y agoSimilar project: http://e-basteln.de/other/stm/overview/ http://e-basteln.de/other/stm/overview/
- dang 6y agoSmall past threads: Home Built Scanning Tunneling Microscope Electronics - https://news.ycombinator.com/item?id=9752215 https://news.ycombinator.com/item?id=9752215 - June 2015 (9 comments) Home-Built Scanning Tunneling Microscope - https://news.ycombinator.com/item?id=8884085 https://news.ycombinator.com/item?id=8884085 - Jan 2015 (1 comment)
- jacquesm 6y agoI think I'm going to build this with my kids. What better way to show them atoms than to actually make them build a microscope that shows you the things directly?
- feralimal 6y agoI'm sure its a cool project. But its not showing things directly, is it? Its interpreting a frequency and converting that to an image. Is it really that different to a music visualiser?
- minitoar 6y agoI mean, what is your brain doing if not that?
- feralimal 6y agoYou don't think there's a difference between what you see with your naked eye, and what is visualised for you by sensors and software?
- gryn 6y agodo you think your eye is not a sensor ?
- feralimal 6y agoOf course your eye is a sensor. As are all your senses. The difference is that the input it receives is unmediated by external sensors and software. Visualising atoms or DNA is fine, but it is an inferior source of information. By a long way. Imagine you were born deaf and couldn't hear music. But that someone showed you a music visualiser. Do you think if you were watching the output of that visualiser you would now know the music in some meaningful way?
- 6y ago
- fit2rule 6y agoThis is an amazing project, in so many ways. My first thought is, the implant business has now got a problem. Soon enough, anyone and their pal will be able, finally, to validate their silicon at adequate scale.
- grkvlt 6y agofinally? imaging a silicon chip has never been a problem and home-build STMs are not needed.
- edge17 6y agoCan someone ELI5 the vibration isolation [0] part of it? I kind of get what he's doing, but would appreciate some analogy if it makes sense to make an analogy. [0] https://dberard.com/home-built-stm/vibration-isolation/ https://dberard.com/home-built-stm/vibration-isolation/
- jacquesm 6y agoIn a nutshell: the vibrations that affect the imaging are pretty high frequency. So to get rid of them he has isolated his whole setup in such a way that if there is a vibration it will be well under the lower cut-off frequency that is part of the measurements. So the whole apparatus may go up or down but that won't affect the measurements. If the whole thing would not be isolated then the rumble from the tires of a passing car or a jet flying over would utterly ruin the measurements. Especially the vibration damping is nicely done, it is zero contact and has the effect of stopping any beginning oscillation in its tracks.
- terofle 6y agoImagine painting with a paintbrush while standing on a jumping castle with 5 jumping children. If you have no vibration isolation, it is nearly impossible to draw a very thin and straight line. (Maybe a bit exaggerated, the vibration analogy is a bit weaker in reality)
- sleavey 6y agoIncidentally all of the techniques listed there are used for suspensions in LIGO, Virgo and other ground-based gravitational wave detectors, where the problem is the same: stop seismic noise from moving the object under test.
- leblancfg 6y agoCan we add [2015] to the title?
- dang 6y agoAdded now.
- feralimal 6y agoYes, look at all that squashed DNA, lol. Seriously though, how do we know that is DNA? It just looks like wiggly worms. And the DNA pic is black and white, but the picture of graphite is in colour. How is it in colour? Is it 'enhanced' with photoshop or something?
- snalty 6y agoFalse colour is pretty much standard for many imaging techniques including STM.
- s0rce 6y agoIts not even really false color, its just a look up table applied to the data, which is some equi-tunneling current or height map, don't know exactly how this is done, bit out of my field.
- jacquesm 6y agoThe tip is pointing down, so an increase in current would indicate a decrease in 'Z' coordinate of the sample surface.
- amelius 6y agoDNA extraction is a routine procedure used to isolate DNA from the nucleus of cells. More here: https://www.sciencelearn.org.nz/resources/2036-dna-extraction https://www.sciencelearn.org.nz/resources/2036-dna-extractio...
- adge 6y agoYou can't actually "see" DNA itself because it is smaller than the wavelength of light. Those groves are 50nm and the wavelength of blue light is about 480nm. So how then are the images generated? It uses a technique called Fluorescence Microscopy: https://en.wikipedia.org/wiki/Fluorescence_microscope https://en.wikipedia.org/wiki/Fluorescence_microscope You essentially stick some special molecules on the DNA that absorb light in one frequency and then they emit light in another frequency. So you blast the molecules with light of one frequency and then use a dichroic mirror to filter that light out and you only see the emissions and thus you see where the DNA is, but you don't "see" the DNA itself. Like STM itself what we mean when we "see" something at those length scales is interesting. Scanning Tunnelling Microscopy is like a blind man reading braille - not really "seeing" anything but getting enough info to describe the picture. source: I used to work in the same lab as Dan. Hi Dan!
- terofle 6y agoThis project is great. Last semester at university lab, our group tried to rebuild it in our lab. Through our spectacular fail, we learned how amazing this project actually is. It is harder than it seems. One can learn very much about piezo electronics, especially about OPamp circuits. And do not underrate the damping!
- jacquesm 6y agoAnd the amplification circuitry, that's not trivial. I was actually surprised he got away with having the wiring out in the open without shielding it for EMI.
- FuriouslyAdrift 6y agoIn the section for "Electronics" is this line "I place a metal can over the STM during scanning to shield the tip and preamp. Without the shield, the images produced by the STM are dominated by 60 Hz noise pickup."
- jacquesm 6y agoAh! I totally missed that, thank you. I thought the pictures were of the scanner in operation, and that detail really confused me.
- ahartmetz 6y agoI worked with a simple STM in a lab exercise. At the beginning, we created a new, clean tip. Guess how we did that?... We cut a piece of ordinary steel wire diagonally with an ordinary wire cutter. Somehow we did it right - the first one worked. It was all somewhat fiddly and sometimes the image was noisy. But we did get images of atoms.
- anitil 6y agoThis reminded me of a Thunderf00t video where he created tiny jets for ammonia. I expected it would be some expensive procedure, but he just heated up some glass, stretched it and cracked it. Not every one worked, but it was surprising how mundane some super precise tooling can be
- regularfry 6y agoIf your process can be "make a tonne of low-precision instances then screen for accuracy" you can get surprisingly good results in general, as long as the accuracy of each instance is relatively uncorrelated. It's a really handy pattern to have in your back pocket.
- oasisbob 6y agoI haven't thought about tips in a while... definitely part of the "magic" of STM. Cutting a wire under tension sounds like it was a pretty common technique, it's the one my lab was using too. If the imaging just wasn't happening, it was common to goose the bias voltage (10x) for a split second in hopes of perturbing the tip enough to get things to go.
- blendergeek 6y agoCan we verify the circuitry on a microprocessor with this microscope?
- rsfern 6y agoWhat size features would you be looking to image? STM typically is used for atomic resolution imaging, so the maximum practical field of view is probably in the 10s of nanometers if you have atomistic resolution. You might be better off with SEM if you need much larger field of view and can live with the coarser resolution limit
- hintymad 6y agoThe geek culture in the US is simply amazing. People build all kinds of miraculous machineries at home, many of which have become world-class products. Some products even changed the history of mankind. What's even more amazing is that the US somehow keeps this culture despite decades of mockery and bullying from the pop culture and from school, and despite that generations of Americans thought that the biggest events had to be the football games in their neighborhood high schools and the coolest people were queen bees and sports jockeys.
- adammunich 6y agoThe football people quickly burn out when nerds are just getting started.
- Sanzig 6y agoThe creator of the linked electron microscope project was a PhD student at McGill (in Montreal) when he built it and (according to his LinkedIn) is currently a startup co-founder in Montreal. So... not sure where US geek culture fits in to this.
- hintymad 6y agoThanks. I falsely assumed that the creator was in the US. Hopefully Canada does not have this strange culture of looking down upon geeks as in the US (so much so that Paul Graham wrote the essay on revenge of nerds, which I couldn't even understand where his emotion came or why he wrote the essay until I came to the US years later).
- kiba 6y agoIs this simply a trope made up and amplified by hollywood?
- vajrabum 6y agoLess smart Americans often have little respect for their smarter compatriots or their smarter compatriot's opinions. That isn't new. Ever hear the term egghead? Modern propaganda about climate and infectious disease have exacerbated the problem.
- ffhhj 6y agoReminded me of this project from 2002 in Geocities: https://web.archive.org/web/20010417002032/http://www.geocities.com/spm_stm/Project.html https://web.archive.org/web/20010417002032/http://www.geocit...
- deleted 6y ago[deleted]
- failwhaleshark 6y agoNeat. IIRC, wasn't there a project using a well-sharpened pencil tip? Also, Applied Science had one in 2011. https://youtu.be/VdjYVF4a6iU https://youtu.be/VdjYVF4a6iU
- hellbannedguy 6y agoReminds me of a Craigslist ad I saw a few years ago. U.C Berkeley bought a new electron scanning microscope, and offered the old one free to anyone who wanted it. The ad right there with the free couches, and nicknacks. I probably couldn’t afford to get it working, but I think about it often. Could you imagine having a scanning electron microscope in your bedroom?
- fest 6y agoThis account details on what you'd go through if you got one https://mobile.twitter.com/nanographs https://mobile.twitter.com/nanographs