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FDC1004: Long distance uni-directional capacitance sensor design

Akshay Ghadage87
Prodigy 60 points
Part Number: FDC1004

We are designing distance measurement sensor using capacitance principal using FDC1004. The sensor plate size we are using is 15cm x 10cm copper plate. Shield size is as same as sensor(overlapping principle- Shield and sensor plate overlap each other). Problem we are facing is

1) Sensing area is not unidirectional. We are using shield for restricting sensing area on one side but shield side is still sensitive to object in near proximity zone( 5cm ).

2) Short distance- Plate area is 15cm x 10cm, which is quite big, but we are getting maximum range as 15cm.

3) If we add the ground plate of same area as shield and sensing plate then we are getting 10cm range.

Please share your thoughts on how can we get maximum possible range with above configuration.

  • 0
    TI__Genius 14270 points
    Hello Akshay,

    The shield should be larger than the actual sensor to help mitigate sensitivity behind the shield, as fringing effects are still present. Also, make sure that the shield protects the sensor traces from the device to the sensor; sometimes these types of issues are not from the sensor but are actually the routing to the sensor.

    Accurate distance measurement using capacitive sensing can be quite tricky, depending on the necessary accuracy. The size and composition of the object greatly affects the response, along with any charge buildup on the object.

    Regards,

    ChrisO
  • 0 in reply to Chris Oberhauser66
    Prodigy 60 points

    Thanks Chris for prompt response!!!

    We are taking care of the traces from sensor to device using shield. The composition of the material is fixed for testing purpose. Is there any way through which we can increase the Electromagnetic field and achieve maximum distance.

    Any specific sensor design pattern that could give maximum EMF and range? I have seen whitepapers from TI, it mentioned 50cm range achieved. Could you please share any document related to their sensor design if possible.

  • 0 in reply to Akshay Ghadage87
    TI__Genius 14270 points
    Hello Akshay,

    Can you post images of your sensor layout?

    Regards,

    ChrisO