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FDC1004: Remote sensing of oil using FDC1004

Ishan Panchal
Intellectual 640 points
Part Number: FDC1004

Hi There,

I have the FDC100EVM and I am trying to check if it can sense the presence of a small plastic test tube filled with oil. Unfortunately, it unable to sense the presence but when I touch the sensor pad it senses. It seems as if proximity detection is not working. Based on my setup and observation I have some questions as listed below :  

  • Can I use FDC1004 for proximity level sensing of oil as a liquid ?
  • If YES, can you please support on achieving same on the FDC1004EVM I have ?
  • If NO, then I would request you to suggest some solutions to achieve same.

For more better understanding on what I am trying to achieve, please see attached image showing basic application of my product.

Thanks..!!!

  • 0
    TI__Mastermind 40295 points

    Ishan,

    With regards to fluids & capacitive sensors, we can say:

    1. With capacitive sensors, better results are possible with non-conductive fluids. 
    2. Larger sensor areas are needed for fluids with low to moderate permittivity.
    3. Smaller sensor areas are possible with higher permittivity fluids.

    General internet search results claim oil is a poor conductor, and has a low to moderate permittivity, so it may be possible to determine oil level with a capacitive sensor.

    The next step will be for you to confirm these characteristics for the type of oil you expect to use, and also consider he effects of potential contaminants if that could be a factor.

    Once that has been confirmed, determining the sensor design will be the next step. We don't yet offer dedicated tools for this, so a first step could be to use the well-known equations as a starting point, and optimize the design thru experiment, or simulations in EM tools like ANSYS.

    You may need to consider the extent of the fluid with respect to the sensor. In other words, a small and/or narrow test tube may not have enough fluid to impact the sensor.
    If that ends up being the case, you might consider experimenting with a grounded version of your sensor on the opposite side of the test tube. This may help boost the sensor's capacitance change as the fluid level varies.

    I know this all sounds vague, so if this doesn't help, we will need some more details about your system, your goals, and your results so far.

    regards,
    John

  • 0 in reply to John Miller - Sensing
    Intellectual 640 points

    Hi John,

    Thanks for the detailed response..!!!

    The type of oil we will use will be a pure marine grade engine oil. 

    Before I respond to the sensor design comment using Ansys, we are currently using off the shelf capacitive sensor (KQ-3120NFPKG/2T) for our prototype but its too costly and off-board, but works fine. I will prefer to do practical experiments with a suggested capacitive sensor chip.

    Here, I am not trying to measure the accurate level of oil, the sensor just needs to provide a trigger once the pipe has oil filled above threshold level. As of now, we are trying to limit oil sample size to 40ml.

    I can provide you with the required details. Its a product that measures ferrous particles in the oil, now instead of that off the shelf capacitive sensor, we need it on board somehow.

    Thanks..!!!

  • 0 in reply to Ishan Panchal
    TI__Mastermind 40295 points

    Ishan,

    You may have seen it already, but have you looked at our app notes on liquid-level sensing?
    You can see the full list on the E2E FDC1004 Frequently Asked Questions page.

    That being said, he shape, size and positioning of your sensors can be critical.
    The container material, its shape, volume and thickness can also be critical.

    It could be helpful to have some additional details.
    If you aren't comfortable doing this in a public forum, we can switch to the private messaging platform on this forum.

    Regards,
    John

  • 0 in reply to John Miller - Sensing
    Intellectual 640 points

    Hi John,

    I went through the appnotes on liquid level sensing and I do have couple of doubts. I understand that it would be a bit of practical trial and error for sensor design.

    This sounds good, we can switch to the private platform to provide you with the required discrete level details. I already have the FDC1004EVM kit to start with something, just not sure if it will measure proximity because as of now it only detects touch.

    Please let me know.

    Thanks..!!!

  • +1 in reply to Ishan Panchal
    TI__Mastermind 40295 points

    Ishan,

    I will close this thread and send you an E2E friend request.
    Please accept the request and then we can communicate via private messages.

    Regards,
    John

  • 0 in reply to John Miller - Sensing
    Intellectual 640 points

    Hi John,

    I have been trying to reach you over messages but I am not getting any response. Can you please check your messages and respond. 

    Thanks..!!!