bladder pressure measuring system

Discussion in 'General Electronics Chat' started by priya vasanth, Jun 10, 2010.

  1. priya vasanth

    Thread Starter New Member

    Jun 10, 2010
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    hai!!
    i am doing my project on bladder pressure measuring system. i have decided to use 150psi-G-4V pressure sensor from "ALL SENSORS" along with PIC16F877 since i need to show the value of pressure in the lcd. also i need to measure the volume of urine coming out when the surgeon applies pressure . so please suggest me the bestvolumetric transducer that can be interfaced with pic along with pressure transducer and the method to interface my pressure transducer with pic ,lcd along with programms. i am using ccs-c compiler and ICD-S programmer.
     
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  2. retched

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    I have not worked with any logic-level volumetric transducers, but I would expect ANY volumetric transducer that is LOGIC LEVEL to work fine with the PIC.

    As long as the transducer is rated for the volumes you are expecting, it should work.
     
  3. priya vasanth

    Thread Starter New Member

    Jun 10, 2010
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    THANKU RM!!!!!!!
    well logic level transducer in the sense??i didnt get it...
     
  4. beenthere

    Retired Moderator

    Apr 20, 2004
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    150 PSI is a pressure more likely for a steam boiler than one's bladder. The sensor will work, but with a tiny response. You might check similar studies to find the usual pressure found, but it is more likely to be around 3 - 5 PSI.
     
  5. priya vasanth

    Thread Starter New Member

    Jun 10, 2010
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    hai thanku 4 suggesting the pressure value.actually i was wrong in calculating the pressure ...200mm of Hg(i.e) ~=5psi-d-4v...thankuu
     
  6. mcgyvr

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    Oct 15, 2009
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    150 PSI... that would be after a heavy...heavy night of drinking and not "breaking the seal" once :)
     
  7. SgtWookie

    Expert

    Jul 17, 2007
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    If I could develop 150PSI of pressure in my bladder, I could write my name in the snow - from Orlando! :D
     
  8. mcgyvr

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    hey look quick its the "golden" gate bridge.. ;)
     
  9. Bychon

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    Mar 12, 2010
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    Great yuks you guys, but OP wants to know what "logic level" means.

    It means that the transducer has an output in the 0 to 5 volt range, right?

    and how would I find that information, he says.

    It will be in the description of the sensors you are perusing. Read the descriptions carefully.
     
  10. Wendy

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    Mar 24, 2008
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    Bladder pressure kills. Rumor has it that Tyco Brahe, a famous astronomer in the 1500's, died from a burst bladder. Ouch.

    If the OP wants a digital display it will likely be some analog components to this device. I'll be interested in the final device chosen.
     
  11. Bychon

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    Mar 12, 2010
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    Yow! I had no idea that star gazing was that dangerous!
     
  12. t06afre

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    May 11, 2009
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    Sigh it has happened again. A simple question has turned into a peeing contest once more:D
    Well hmm back to topic. I do not have very accurate figures on this topic. But from what I remember. It think it will be in the area of about 20 mmHg in rest conditions for healthy people. But I have to check that numbers
     
  13. priya vasanth

    Thread Starter New Member

    Jun 10, 2010
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    hai!!!
    i thought of making use of pressure transducer which works on piezoresistive effect... now i was asked to search a transducer based on load cells or strain gauge .could you ploz help me in finding the best loadcell that can be interfaced with a pic and measures pressure in the range of (0-200)mm of Hg.
     
  14. retched

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    Is this to be connected to a catheter? I hope? And you will need a way to keep one persons 'test' from mixing with the next persons 'test'.

    Piezo may not be the best idea. Piezo will report pulsing pressure, not steady. It only creates a signal while being "flexed".

    200 millimeters of mercury in 1 mm steps is a little under 8 bits of resolution. Do you think you will require more the 1 mm steps?
     
  15. retched

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  16. t06afre

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    Common medical pressure sensors is not piezoelectric, but piezoresistive pressure sensors. Such sensors can be made very small and cheap. As they are very often based on silicon, and produced in the same manner as ICs. It is quite common to mix the two terms together.
    Most medical pressure sensors are of 5µV/V/mmHg sensitivity. They need an excitation voltage (AC or DC). And they give a differential output. So you will need a instrumentation amplifier. Do NOT try to build one your self, with discrete components. Get a commercial type of high quality.
    To get you started I suggest you Google
    piezoresistive pressure sensors
    instrumentation amplifier
    Edit: Try this link also http://ww1.microchip.com/downloads/en/AppNotes/00695a.pdf
     
    Last edited: Jun 11, 2010
  17. SgtWookie

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    Jul 17, 2007
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    "Logic level" is generally considered to be low voltage. Standard TTL logic level is <0.8v for a logic zero, and >3v for a logic 1. However, CMOS versions of standard TTL IC's are generally operated on anywhere from 2.5v to 5.5v.

    "Logic level" MOSFETs are usually rated for Rds(on) when their Vgs (voltage on the gate referenced from the source terminal) is 4.5v.

    If you want code samples, you can find plenty on the Microchip website, and in the MPASM suite, which is a free download.

    The PIC16F877 is basically obsolete. Use a PIC16F887 instead.

    If you are going to use an LCD with individual segments, use a uC that is designed to drive them, like a PIC16F193x series.
     
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