4 ms·

> Instead, a laser beam burns a 0.3mm-wide hole in the shell. Then, air pressure is applied to the shell exterior, pushing a drop of fluid out of the hole. The

• majewsky 6y ago
  I would assume the external pressure causes the shell to elastically deform so that it contains less volume, hence a drop of fluid is squeezed out.
  • aazaa 6y ago
    Isn't that drop experiencing the same pressure as well? If so, what causes the fluid to escape?
    • notatoad 6y ago
      that droplet would be experiencing the same pressure from the air pushing inward, but also a pressure pushing outward proportional to the amount the egg has contracted. more pressure pushing out than in means fluid comes out.
      • ac42 6y ago
        Why would the egg contract in the first place? It's more likely that the "applied pressure" is simply negative...
        • deleted 6y ago
          [deleted]
        • majewsky 6y ago
          It's the same as when you squeeze a plastic bottle. If the cap is unscrewed, the liquid will splash out of the opening. The egg is just a bit less flexible than the plastic bottle, so the effect is less visible.
• mohn 6y ago
  That's a good question! I think you're correct that if the increase in external pressure were uniform around the whole egg, it would not push fluid out of the pinhole. Looking at this 2020 video[0], it seems like the procedure might be: 1) Laser burns pinhole through shell. 2) Robotic pipette applies the marker chemical onto pinhole. 3) Pneumatic grabber picks up egg by its pinhole end (so the atmospheric pressure, relatively higher than the pressure inside the grabber, is pushing a little fluid out). 4) Egg is stored so marker chemical can be read later after it has undergone its reaction. I found a 2018 video as well[1], but the machine looks a lot different and it's harder to tell how it works. [0] https://www.youtube.com/watch?v=OeAWcF1MxNo&t=26s https://www.youtube.com/watch?v=OeAWcF1MxNo&t=26s [1] https://www.youtube.com/watch?v=dEtauP71oLU https://www.youtube.com/watch?v=dEtauP71oLU
  • aazaa 6y ago
    Hadn't seen video[0]. From that view, it's not clear how the air pressure around the egg is increased. The end of the carousel appears to be where the laser flash occurs, but I see no way to raise/lower air pressure inside the compartment.
    • mohn 6y ago
      I don't think there is any compartment with pressure above atmospheric, but the passage quoted from the article does make it seem that way, hence the confusion. I think the pneumatic grabber creates a sealed region of less-than-atmospheric pressure around the site of the pinhole. Effectively, this is like increasing the pressure outside most of the eggshell. In the 2020 video, the shot that starts at 55 seconds shows the whole carousel. A pair of robot arms are using pneumatic grabbers to load eggs onto the carousel, they go under the high power laser, then pass under the pipette robot arms, and finally are removed from the carousel by a similar pair of robot arms with pneumatic grabbers (it is at this last step that I suspect the fluid passes through the shell).