Shop OBEX P1 Docs P2 Docs Learn Events
Dissolved Oxygen sensors...ideas? — Parallax Forums

Dissolved Oxygen sensors...ideas?

gibbmangibbman Posts: 98
edited 2006-06-07 01:12 in General Discussion
We have a need for a means of reading dissolved oxygen (in brackish estuarine waters) for a college marine science project. High accuracy is probably not critical, but the ability to discern at what general level of O2 the bottom-dwelling critters, like crabs, are affected. Any leads on literature for sensor design, or reasonably priced existing sensors? Have looked around a bit, including·the aquarium-hobby sites, but haven't come up with anything that we can afford. I am hoping that the group can suggest some avenues to explore.
Thanks from me and my students,
Jim

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
In the end, it seems that it's all about getting the LEDs to blink....

Comments

  • Kevin WoodKevin Wood Posts: 1,266
    edited 2006-05-12 05:29
    How about this company?

    www.americanmarineusa.com/
  • Tracy AllenTracy Allen Posts: 6,666
    edited 2006-05-12 16:40
    Vernier is the source for education:
    www.vernier.com/probes/do-bta.html

    At $200, that is about as low as they come. I don't know any easy way around it.

    Professional probes (more rugged for process control and monitoring) cost twice as much:
    www.sensorex.com/products/do_probes/DO_sensor_products.html

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Tracy Allen
    www.emesystems.com
  • gibbmangibbman Posts: 98
    edited 2006-05-13 11:47
    Kevin and Tracy:
    Thanks for the leads. All three have interesting products. I was hoping for an "easy way around it" as Tracy mentions, but more on less expensive than easy! It is as I had feared. Back to the drawing board...
    Thanks again,
    Jim

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    In the end, it seems that it's all about getting the LEDs to blink....
  • John R.John R. Posts: 1,376
    edited 2006-05-13 14:48
    Jim;

    Time to take advantage of a few things you have working for you:

    You're a college student.
    You're working on an "eoco" project.
    You're a retired service man (thank you).

    At 200 to 500 bucks, what you're after isn't "astronomical" in cost, and it really shouldn't be too hard to find a business willing to order the thing and either donate it to you, or find someone sympathetic and have them order one and "loose" it. Some companies are "into" this type of help, others are not. (e.g. my current employer would have problems, but with my prior employer we either outright donated openly, or "lost" about 10 - 20 K per year on stuff like this. All we asked in return was an "invitation" to the final presentations or a copy of the report. And that was so that we could recognize the efforts of the students we helped.

    Good luck!

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    John R.

    8 + 8 = 10
  • gibbmangibbman Posts: 98
    edited 2006-05-18 16:59
    Oh John!

    You've mistaken me for a student! I am, in fact, the teacher - but THANKS, as you make me feel younger than my 55 arthritic years already!

    By "back-to-the-drawing board", I meant I would probably have to work them into a grant proposal. But I like your idea of hitting up a local, sympathetic company, although we have little other than service companies around here (read real estate and restaurants). But it's worth a shot!

    Thanks,

    Jim

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    In the end, it seems that it's all about getting the LEDs to blink....
  • steve_bsteve_b Posts: 1,563
    edited 2006-05-18 18:26
    Appeal to places like Hoskin Scientific or Vaisala....they may have old models of such devices that they'd be willing to part with.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    ·

    Steve

    "Inside each and every one of us is our one, true authentic swing. Something we was born with. Something that's ours and ours alone. Something that can't be learned... something that's got to be remembered."
  • bjhamltnbjhamltn Posts: 21
    edited 2006-05-19 17:59
    Could an O2 sensor from a car be used?
  • gibbmangibbman Posts: 98
    edited 2006-05-24 00:24
    Steve,

    Thanks, I'll have a look and maybe give this a try.

    bjhmlton: Wow, you got me excited...but I went to "Howstuffworks" and it seems they don't operate at all until they reach 600F in the exhaust stream. Boohoo. This approach is actually what I hoped for, that somehow I could construct something that might work. Way too much involved, I guess.

    Thanks all,

    Jim

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    In the end, it seems that it's all about getting the LEDs to blink....
  • rscconradrscconrad Posts: 6
    edited 2006-05-30 12:02
    Heres is a way that should work.

    Ruthieum fluoresces when excited with a blue LED lamp.· It emits around 600 nm(red).

    Use a blue LED an read with the color sensor that Parallax sells.· YOu should be able to read on the blue color part of it.· I don't kow hte specifics of the filters they use.

    If· you go to the SIGMA site they have a PDF you can download on how to impregenate the ruthium into polystyrene beads and all the specs on excitation and emmision.

    Assuming you have the hardware for the basic board it will cost around 50 bucks for the Ruthieum.·· Less if you find someplace that sells it in smaller quantites.

    Good luck

    Robert
    ·
  • rscconradrscconrad Posts: 6
    edited 2006-05-30 12:12
    Sorry,

    I should have also said the more oxygen in the envioment the less the ruthieum fluoresces in a linear manner.

    Robert
  • ellizardellizard Posts: 106
    edited 2006-05-31 15:59
    rscconrad said...
    If· you go to the SIGMA site they have a PDF you can download on how to impregenate the ruthium into polystyrene beads and all the specs on excitation and emmision.
    Could please be more specific about?
    I'm interested in the subject but could not find (after a deep googling) anything relate to ruthieum and Sigma.

    A·link would be appreciated

    many thanks

    Stefano Caruso
  • rscconradrscconrad Posts: 6
    edited 2006-05-31 17:42
    Here you go.

    THis should be all you need.· It is sigma product number 85793.

    Robert
    pdf
    pdf
    oxygen.pdf
    97K
    txt
    txt
    oxygen.txt
    2K
  • ellizardellizard Posts: 106
    edited 2006-06-01 08:05
    As usual the Parallax forums are prone to almost immediate and complete response.



    MANY THANKS

    stefano Caruso
  • GadgetmanGadgetman Posts: 2,436
    edited 2006-06-01 11:06
    Just curious...

    Won't the dissolved oxygen change the weight of the water?
    (I'm thinking something similar to those instruments you use to measure the charge on Lead-acid batteries)

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Don't visit my new website...
  • Bruce BatesBruce Bates Posts: 3,045
    edited 2006-06-01 11:37
    Gadgetman -

    When you are determining the charge in a lead acid battery with a battery hygrometer, you are measuing the specific gravity of the fluid in the battery cells. I doubt that the water in an estuary (as is the fluid to be measured here) will change much in terms of specific gravity, merely based on the oxygen content - dissolved, undissolved, or otherwise.

    This is so, if for no better reason, than the definition of specfic gravity, since specific gravity is defined as the ratio of a given density of a particular fluid as compared to the density of the same volume of some reference standard. The most common reference standard is usually WATER!

    Regards,

    Bruce Bates

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    <!--StartFragment -->
  • bubbleheadbubblehead Posts: 36
    edited 2006-06-02 05:30
    As I recall, blood oxygen sensors (the things they clip on your finger in the hospital) work by transmitting two different 'colors' (or frequencies) of light through your finger.· One frequency is absorbed by the oxygen in the blood.· So, the ratio of the received light at the two frequencies is indicative of the oxygen content of the blood.· I think one of the lights is a red LED, the other is an IR LED.

    In essence, the·blood oxygen sensor·is a colorimeter.

    Perhaps you could use a similar technique.· Build a device with colored lights (say red, greed, blue and IR LEDS)·opposite a sensor with a space for a test tube to be inserted between them.· Compare transmision readings with an empty test tube with readings with a test tube with a sample in it.· Obviously, you will need to calibrate the sensor by comparing the results to the results of a standard test such as with an O2 meter or titration.
  • gibbmangibbman Posts: 98
    edited 2006-06-07 01:12
    Wow! Doc keeps me away for a few days, and look at the life in the thread! Thanks, all.
    Robert: I think I might as well get the $200 model already designed, since it is also necessary for the readings to take place without operator intervention over a certain amount of time, say two or three days.
    Gadgetman, Bruce, and bubblehead: Thanks for the posts. I may not have made it apparent earlier, which is my fault. This apparatus needs to be unattended, and data downloaded maybe twice a week or so. I think that Tracy had it right earlier on, when he said he didn't know any way around buying the $200+ inline probes...looked at the fingertip oxygen monitors, as I had been thinking about these, but durn it, they need hemoglobin in pulsing arterial blood flow to figger out how much oxygen there is....
    Thanks all,
    Jim

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    In the end, it seems that it's all about getting the LEDs to blink....
Sign In or Register to comment.