- advertisement -

Reverse-engineering the Omnipod Bubble

Discussion in 'Parents of Children with Type 1' started by Darryl, Feb 14, 2010.

  1. funnygrl

    funnygrl Approved members

    Joined:
    Nov 2, 2005
    Messages:
    2,324
    I've read it many times on their site and in their literature. I can't find any examples right now. I did see in a video just now in the "how the system works" section where it says it automatically purges out air.
     
  2. Darryl

    Darryl Approved members

    Joined:
    May 8, 2008
    Messages:
    4,313
    Here's the rest of the story in 4 separate posts.
    Not essential reading for pod users, but possibly of interest ;)

    1) Someone asked about the plunger and O-ring design. Here it is. There are 2 rings.

    [​IMG]
     
  3. swellman

    swellman Approved members

    Joined:
    Jul 30, 2008
    Messages:
    3,544
    How do you think they determine the initial volume?
     
  4. Darryl

    Darryl Approved members

    Joined:
    May 8, 2008
    Messages:
    4,313
    How does the pod detect occlusion? Here's what I think after taking it apart:

    When the pressure reaches a certain point, the membrane with the little metal ball will start to push out.
    This will force the little metal ball into the two electrodes shown in the bottom photo, connecting them electrically.

    [​IMG]

    [​IMG]
     
    Last edited: Feb 17, 2010
  5. swellman

    swellman Approved members

    Joined:
    Jul 30, 2008
    Messages:
    3,544
    That would imply the remaining insulin value was nonsensical. No?
     
  6. swellman

    swellman Approved members

    Joined:
    Jul 30, 2008
    Messages:
    3,544
    I replied with a full paragraph but found myself questioning my assumptions. Do you think the piston is at full retraction prior to filling? That would make some sense as the pressure would indicated with the "bubble" was expressed but would have to allow for some error due to residual air and it's compressibility.

    I had assumed the piston was at empty and somehow determined filling volume ... er ... in another way.

    This would be easily confirmed by opening an expired pod prior to filling and examining the piston position.
     
  7. TRICIA4

    TRICIA4 Approved members

    Joined:
    Feb 9, 2010
    Messages:
    49
    Quite a while ago a rep from Insulet told me that the clicks are meaningless and were added because consumers complained that they didn't know if the priming was really taking place because it was silent. Just thought I would mention that. I really appreciate all of your research, I find it very helpful.
     
  8. swellman

    swellman Approved members

    Joined:
    Jul 30, 2008
    Messages:
    3,544
    I call BS on your rep.
     
  9. TRICIA4

    TRICIA4 Approved members

    Joined:
    Feb 9, 2010
    Messages:
    49
    Well, you could be right. It was actually when I called Omnipod (not my local rep) for issues we were having at the time. It was months ago, maybe even a year or so, but I think it was when I was calling to get more info on the recall on pods that were making a "crackling" sound during priming. I mentioned that I noticed that the "clicking" sound is different sometimes, and I was trying to interpret that. This is when he told me the "clicking" was added for no real reason. Give them a call, see what they say? My guess is...it all depends on who you talk to.
     
  10. swellman

    swellman Approved members

    Joined:
    Jul 30, 2008
    Messages:
    3,544
    There was a recall?!?!?!

    EDIT: I'm pretty sure there was no recall.
     
  11. Flutterby

    Flutterby Approved members

    Joined:
    Nov 11, 2006
    Messages:
    14,623
    I believe the omnipod recall was false and just a rumor.. I can't find anything anywhere on the internet that states there was a recall, ever.. if there was, someone here would surely have known about it and posted the important information.
     
  12. swellman

    swellman Approved members

    Joined:
    Jul 30, 2008
    Messages:
    3,544
    That and the FDA would have it on their website.
     
  13. Darryl

    Darryl Approved members

    Joined:
    May 8, 2008
    Messages:
    4,313
    For a brief time there were reports of pod's not filling properly and making a noise. We did not experience it, but it was reported here by some people.
     
  14. Darryl

    Darryl Approved members

    Joined:
    May 8, 2008
    Messages:
    4,313
    The clicks are each 0.05u. If you open the pod and spin the gear yourself, you'll hear them. As the gear turns, each click rotates the spiral thread on the plunger in to push through .05u. As far as I know, this is the same on other pumps, which also click for the same reason.
     
  15. Darryl

    Darryl Approved members

    Joined:
    May 8, 2008
    Messages:
    4,313
    I'll take a look at that. It's possible it could be the other way around, if it is possible for the plunger to move backwards easily when filled, but I don't think that would be possible given the spiral thread and gear that clicks in only one direction.
     
  16. swellman

    swellman Approved members

    Joined:
    Jul 30, 2008
    Messages:
    3,544
    I think you are correct. I further dismantled the one I was playing with and it does appear that it would be much more likely that the piston is fully retracted. This means that everyone starts with a varying sized bubble - based on the fill volume. I would also assume that everyone's priming "clicks" were different as well. I noticed that it takes quite a bit of pressure to move the diaphragm and ball. I wonder if it serves as an occlusion detector or, perhaps, serves a few purposes.
     
  17. Mom2Kathy

    Mom2Kathy Approved members

    Joined:
    Feb 17, 2009
    Messages:
    605
    I have to say that all this discussion is extremely interesting. I have learned a lot about the workings of the pod and am even more amazed at the engineering it took to accomplish this technology. I'm very pleased we have this pump!

    Darryl - LOVE the pictures! :)
     
  18. vettechmomof2

    vettechmomof2 Approved members

    Joined:
    Jul 13, 2007
    Messages:
    3,037
    No real recall but if while priming you heard a crackling sound you were supposed to deactive and return that pod instead of using it.
    I want to say this was over 1.5 years ago???
     
  19. evinsmom

    evinsmom Approved members

    Joined:
    Nov 27, 2007
    Messages:
    90
    Very interesting conversation. I just called Insulet customer service because of some pod failures. During the course of questions on what "I" did wrong, I got a new one - "what was the pod's orientation during priming?" The rep told me that the pod should sit horizontal while priming and in the container it was shipped in (made especially so the pod wouldn't rock during priming). I said that was news to me and no one had ever mentioned it before in the almost 3 years we had been using the pod. He said there was some "misinformation" on the web about how to prime a pod and that it should remain in the package with the cap on during priming. When I asked if priming in another orientation would cause a pod failure or any other problems, he hemmed and hawed but never really answered.

    Anybody heard this before? Doesn?t make much sense with everything Darryl has learned and shared with us.
     
  20. saxmaniac

    saxmaniac Approved members

    Joined:
    Jun 1, 2007
    Messages:
    4,057
    Well, we primed that way for a very long time, as it was the natural thing to do... and still had plenty of post-change highs - but I'll try it again if they say so.

    The highs caused us to try other orientations, not the other way around.
     

Share This Page

- advertisement -

  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.
    Dismiss Notice