Living Photonic Crystals: These scanning electron microscope images of tiny diatoms have been digitally colored.

Living Photonic Crystals: These scanning electron microscope images of tiny diatoms have been digitally colored. But in real life, their glass-like skeletons have a special property of interfering with light waves, reflecting light in different colors depending on the viewer’s angle, much like an oil slick on water. This is because the array of tiny holes studding the diatom surface match the wavelength of visible light and behave as photonic crystals.

• Photonic crystals are optical nanostructures which affect the path of photons just as semiconductors affect electrons. They have periodic (repeating) changes in dielectric constant. Photons pass through this structure – or not – depending on their wavelength. The repeating pattern of solid and water filled holes on diatoms make them natural photonic crystals.

• Diatoms could be used to make iridescent cosmetics, paints and fabrics and even credit card holograms. They are cost-effective and biodegradable. Up to 1 tonne of diatoms can be made per day, starting with only a few cells. Diatoms are microscopic, photosynthesizing single celled microorganisms. Did you know that they produce a quarter of the oxygen that we breathe?

Images: Diatoms looking like various artifacts, from a pill box to a peanut were selected from http://www.flickr.com/photos/galfaye/

#scienceeveryday  

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67 Responses to Living Photonic Crystals: These scanning electron microscope images of tiny diatoms have been digitally colored.

  1. Jim Carver says:


    They also make great filters and are useful in geology.

  2. Rajini Rao says:


    What geological applications, do you know, Jim Carver ? I know they are used as coatings on lenses and mirrors.

  3. Luther Cale says:


    These are interesting images. Thanks for sharing!

  4. james kalin says:


    good for pissing off slugs too. 🙂

  5. Rajini Rao says:


    That’s right, forgot to add that diatomaceous earth is a natural pest deterrent. It cuts into the soft slug bodies…


    Thanks, james kalin !

  6. Jim Carver says:


    Rajini Rao Diatoms, radiolaria and forams (foraminifera) are useful in constructing past climate and environments. They tend to live in specific environments and that makes them useful in those studies.

  7. Rajini Rao says:


    Ah yes, thanks Jim Carver . The earliest fossils are 100 million years old!

  8. Jim Carver says:


    Rajini Rao Yeah, and they’re pretty happy, haven’t changed much. Just like a shark’s tooth, not a very good index fossil.


    Another thing they’re good at is cleansing your system. Just put a teaspoon of DE (make sure it’s food grade kind, not swimming pool filter) in a glass of water and drink it down. Tastes like dirt. It is non-selective and will pull everything out, so make sure you put good stuff back. Useful for heavy metals and chemical toxins.

  9. Rajini Rao says:


    Interesting, I was just watching a YouTube video on drinking diatomaceous earth! I can imagine it is a good chelator, but wouldn’t it just stay in the digestive tract? Can it get absorbed into the blood stream? I’ll check around for more info, thanks.


  10. Awesome post Rajini Rao … Especially because its something that if can really be adopted, will effect our #future in much better ways than the current tech we have. Plus, they are #organic.

  11. Jim Carver says:


    Rajini Rao I’ve used it for years and it can make you feel great. You have to be careful though. Make sure it doesn’t have anything in it. We used to sell it and we ran lab tests to make sure it was clean. The best source we found then was from Utah.


    Take it on an empty stomach and drink plenty of water. After that put good stuff back. I have taken it everyday for at least a week and had no ill effects. Actually felt great and stopped for a while. There are other things that will do the same thing, like charcoal (yeck) and pectin. But I don’t think any of those are as effective.

  12. Jim Carver says:


    Oh about your system? No, it just washes out of the colon, very little absorption, what little might go in is just silica and that’s no problem. 

  13. Rajini Rao says:


    Just what I was thinking, thanks Jim Carver !

  14. Rajini Rao says:


    I’m not finding any controlled studies published on PubMed on medical uses. The food grade version is inert and safe, so at the minimum it appears not to do harm..given the personal anecdotes on here. It likely helps with roughage, and as a chelator that binds digested food and blocks absorption (leading to weight loss). That’s an educated guess 🙂

  15. Jim Carver says:


    Rajini Rao They wouldn’t want to research this, it’s too cheap.


    I don’t know about “roughage” yeah it’s pretty rough all right. 🙂


    But you take it on an empty stomach, not with food ever. And that’s what it does, it’s a chelator. The only health hazard is breathing the dust. Anybody watching at home: Don’t Breathe the Dust 🙂

  16. Rajini Rao says:


    That’s right, I did see published studies on lung cancer risk with dust inhalation by miners of diatomaceous earth.


  17. I think I read on Lifehacker or something about the health properties of diatomaceous earth, should look up if its possible to find it in #SriLanka. Wanted to try it out. And I have to agree with Jim Carver , doubt many people would reaseach this unless they had a gain. Rajini Rao , thanks for your great tip though. Its actually worth looking into on the long term. Wonder if it has any other untapped uses.


  18. Rajini Rao Thanks for the wonderful share.

  19. Jim Carver says:


    Silicosis, similar to the effects of asbestos. See also Mesothelioma.

  20. Rajini Rao says:


    Yikes! It’s also used in face powders, toothpaste, cat litter..


    But this blew me away: “In 1866, Alfred Nobel discovered that nitroglycerin could be made much more stable if absorbed in diatomite (diatomaceous earth). This allows much safer transport and handling than nitroglycerin in its raw form. He patented this mixture as dynamite in 1867.”

  21. james kalin says:


    did someone say dy-no-miiite?!


    http://bit.ly/taTY0


    link following by those born after 1980 might cause dizziness and confusion. check with your doctor if symptoms persist.

  22. Rajini Rao says:


    james kalin , LOL! But  I didn’t really watch that show 🙂

  23. Jim Carver says:


    I think the first dynamite made used excelsior or wood shavings, i.e. sawdust. After that DE was found to work better because it didn’t sweat as much.

  24. Rajini Rao says:


    For any other ignoramus like me, excelsior: Slender, curved wood shavings used especially for packing.

  25. Jim Carver says:


    Yep, but in the 1800’s it had a broader meaning. I’m even old enough to know the older meaning. I guess it has become an archaic term.


    The one thing nice about the invention of dynamite was that the users didn’t have to sweat as much too. 🙂

  26. Rajini Rao says:


    I guess vitamins and other nutrients? I’m guessing the diatomaceous earth does not discriminate what it binds, within a range of charge/size.

  27. Brian Johns says:


    Very neat. Are they bioluminescent or unscented 😉

  28. Rajini Rao says:


    Brian Johns , no bioluminescence that I’m aware of, and more biofouling than scenting 🙂 They can form tons of scum in harbors and on ships.


    Feisal Kamil , I think that’s what it means. If you consume the stuff, it can deprive you of nutrients so one would have to take supplements or something.

  29. Jim Carver says:


    Feisal Kamil Yes, that’s correct what Rajini Rao said. Eat pure food and take supplements if you are inclined. I personally take supplements and find that I do better than without them, but it’s a personal choice. Theoretically it’s possible to get everything you need from diet alone. But who can consistently eat a good diet everyday? I work at home and sometimes find it difficult.

  30. Rajini Rao says:


    I hope not, Feisal Kamil ! We may well be dead without our bacterial flora in our guts.

  31. Rajini Rao says:


    Actually, one can. Heard of stool transplants? 🙂


    I know docs who do this, seriously.

  32. Jim Carver says:


    There would be some loss of flora. I haven’t ever experienced a problem with it. I regularly eat yogurt with live cultures and I would recommend that.


    Probably try a glass and expect it to taste like dirt and irritate your throat a bit. The stuff we used to sell didn’t bother my throat but some stuff I got after I ran out does a little. It goes away in a few minutes anyway.


    You can feel it go through your system all the way to end and it’s not bad. And do make sure you stay hydrated. It’s not dangerous, but with any chelation technique you should take care. ☯:)

  33. Rajini Rao says:


    Eeek, no 🙂 It (fecal transplant) is therapeutic procedure. But one that is gaining more practice, so I hear.


  34. This looks just like it was made from foam rubber. 

  35. Deeksha Tare says:


    Wow!!!!! Amazing Rajini Rao !!


  36. Diatomaceous earth is used to shred slugs in gardens (as has been mentioned in this thread).  Does this photonic aspect have anything to do with how they can destroy slugs or is it another property of theirs that does the dirty (ha!) work?  It is the crystal structure probably?

  37. Rajini Rao says:


    I was wondering if you had used this in your garden, Michelle Beissel ! I’ve not had a problem with slugs.


    The slug slaying properties come from sharp shards of silica in diatomaceous earth. A purely physical property of these shells. The photonic properties come from the regular repeating holes that are tiny enough to interfere with light waves..also a purely physical property, although I expect that the shells would need to be intact and not damaged or broken.

  38. Matt Kuenzel says:


    These guys are photosynthetic, right, so I’m guessing that the shells are transparent (?) to sunlight. It would be interesting to see what they look like in large numbers. Do they form colonies or just float around?

  39. Rajini Rao says:


    Matt Kuenzel : yes, they are photosynthetic. It is speculated that the periodic structures help with light harvesting. For example, this paper on “Lensless light focusing with the centric marine diatom Coscinodiscus walesii” suggests that the structure acts like a microlens: http://www.opticsinfobase.org/oe/abstract.cfm?uri=oe-15-26-18082


    I found this quote by Andrew Parker, Oxford: “It’s a mystery why diatoms have iridescent qualities,” says Professor Parker. “It may have something to do with maximising sunlight capture to aid photosynthesis in some species; on the other hand, it could be linked with the need to ensure that sunlight capture is not excessive in others.

  40. Matt Kuenzel says:


    Amazing what these little guys can do: ” A 100 µm spot size of a red laser beam is narrowed up to less than 10 µm … The focusing effect is due to the superposition of the waves scattered by the holes present on the surface of the diatom valve.”


    Also, “it could be linked with the need to ensure that sunlight capture is not excessive in others,” would be a nice example of cooperation.

  41. Matt Kuenzel says:


    They reproduce sexually, hmmm, maybe their beauty is the way they attract the opposite gamete !?!

  42. Rajini Rao says:


    I forgot to check whether they live in colonies, Matt Kuenzel . As far as attracting the opposite mating type, they would need to “see” them first, wouldn’t they? 🙂

  43. Matt Kuenzel says:


    [just kidding about attracting the opposite] …


    I’m guessing that they must form sheets / films if they both need sunlight and access to the opposite mating type.

  44. Matt Kuenzel says:


    The shape of the cap on that diatom in the first photo looks like it could interlock with another diatom above. So maybe that particular species builds filaments by “stacking” a series of individuals (?).

  45. Rajini Rao says:


    Good point..actually you can see the interlocking in both links. In the first, they form that ring (notice all three have eight unit cells each?) by linking at one end. Even the Nat. Geo. pix shows them interlocking in head-to-tail pairs. Amazing!

  46. Rajini Rao says:


    When you put it that way, Mr. Kamil. 😀

  47. Rajini Rao says:


    You are welcome, Alejandro Cañete . I’ll see you on FB then 🙂

  48. Rajini Rao says:


    Actually, that’s a beautiful collection of diatoms! You should share them on G+ too. If you do, post the link here, thanks 🙂

  49. Rajini Rao says:


    I hope Matt Kuenzel , Michelle Beissel , Jim Carver , Feisal Kamil and others on this thread take a look at the collection that Alejandro just posted (link above). Amazing diatoms.


  50. Remarkable images, thanks Alejandro Cañete and Rajini Rao (for encouraging me to click on the link, lol)

  51. Matt Kuenzel says:


    Amazing! They are so intricate … some are perfectly symmetrical and some appear to have patterns like flower petals … Nature is truly awesome. Thanks Alejandro Cañete and Rajini Rao 


  52. Really amazing … :-O

  53. Rajini Rao says:


    Hi Magnus Fahlén ! Strange and wonderful, yes 🙂


  54. Hi Rajini Rao … 🙂


    Hope everything is fine with you !!


    I’m enjoying my 3:rd week of vacation and have one more to go … ^^


    Trying to get things done in my garden and with the house … 🙂


  55. Btw … I love your sience posts Rajini … 🙂

  56. Rajini Rao says:


    Enjoy your vacation, Magnus Fahlén . I’ll be going on vacation in a couple of weeks too. Thanks for your kind words, love to hear them 🙂


  57. Thanks dear Rajini Rao … 🙂


    Wish you a nice and relaxing vacation !!


  58. I’d like to see some of the products.  Sounds great!!

  59. Rajini Rao says:


    Which one did you say you liked the best, Thomas Kang ? The one with a heart on it’s sleeve? 🙂

  60. Thomas Kang says:


    That was the one image I didn’t plus, yet that’s the one I recall most clearly looking at these images again.


    Another interesting thing is that my preferences haven’t changed in this regard; that’s the same one I still wouldn’t plus. I like the color, but I think my brain is mildly perturbed that the four “strings” extend out to the edge, loose and unconnected, whereas by contrast, all of the other images have give off a sense of greater cohesion (sphere, circle, etc.. with no loose ends).


    I don’t mind loose ends, but not so much in this way — very difficult to express in words because I myself have trouble understanding why.

  61. Rajini Rao says:


    Those side strings reminded me of tape yarn and so it actually fit with the knitting/sweater image in my head.


    It’s good to know that people don’t plus posts mindlessly 🙂

  62. Thomas Kang says:


    Now, if those ends were even loosely threaded, especially in a random-yet-somehow-mysteriously-balanced-asymmetrically-by-nature sort of way, and the camera shot was taken just a little farther back to show the interaction of those strings, then I know I would have liked the image much more.


    I wouldn’t make any inferences on the basis of my plussing behavior on these pics. I may have had clear preferences, but that doesn’t mean that my choices weren’t mindless nonetheless!


  63. as usual, a very interesting photo.

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