FDC2214: Detection of human hand only

Haresh Prajapati

Prodigy 95 points

Part Number: FDC2214
Other Parts Discussed in Thread: FDC1004

Tool/software:

I have design challenge to make the LED camp with the human hand detection. Requirement mention below.

LED lamp has close body which is cover by the plastic part so no external exposed of electrical parts
Need to detect the human hand with the maximum range of 10-20 cm
Other object should not be detected

To achieved the requirement we come to know that the capacitive proximity sensor is the closet option.

Is FDC2214 suitable for that?

Suggestions are welcome

10 months ago

0 John Miller - Sensing 10 months ago

TI__Mastermind 40295 points

Haresh,

From an electrical perspective, human skin looks like a conductive, grounded surface.
Likewise, any conductive, grounded surface could activate a capacitive sensor, with dependencies on the objects size, shape and distance.

Is there some way your application could be made to allow only a hand in the 10cm-20cm range near the sensor, and exclude all other objects?
If other objects can't be completely excluded, could your application work with or impose limits on size, shape an orientation of nearby objects, including the hand that should be detected?

Regards,
John

0 Haresh Prajapati 10 months ago in reply to John Miller - Sensing

Prodigy 95 points

Hello John,

Thanks for the reply

In our application we want to allowed to detect human hand only up to 10 cm (20cm would be great)

We can set the limit of size based on the human hand.

Below is some basic information of lamp

we will design PCB with the vertical mount
Attached image is the PCB size in the lamp
It will be two layer PCB, we will add sensing both side of PCB.

0 John Miller - Sensing 10 months ago in reply to Haresh Prajapati

TI__Mastermind 40295 points

Haresh,

If the detection circuit is triggered by an object that is not a human hand, would that be considered a failure?
The main worry here is that other conductive objects and/or the approach of skin that is not part of a hand will trigger a false detection.

Please note that we have a page of frequently asked questions for the FDC1004 at the E2E FDC1004 Frequently Asked Questions page.
It includes a comprehensive list of app notes including FDC1004: Basics of Capacitive Sensing and Applications.
It also includes a detailed overview of the FDC1004 including theory of operation, applications, and critical specs.

Regards,
John

0 Haresh Prajapati 9 months ago in reply to John Miller - Sensing

Prodigy 95 points

Hello John,

Its ok to detect the human skin, For other object we can take care by the mechanical design restriction so no object can come closer.

Then i am assuming FDC1004 would be the best choice for this application.

0 John Miller - Sensing 9 months ago in reply to Haresh Prajapati

TI__Mastermind 40295 points

Haresh,

The FDC1004 is the best starting option.

That being said, some simple calculations hint at the possible sensor dimensions.

If we use the idealized parallel-plate capacitor equation - εA/d - to estimate sensor dimensions, we get:

Csensor ≈ εA/d → A = Csensor·d/ε

The FDC1004 can detect a capacitance of 0.1pF pretty well, and the stated detection distance is 10cm, so the sensor area would be:

A = (0.1e-12F)·(0.01m)/(8.85e-12F/m) = 0.0001m^2

If we assume a square sensor, each side is about 10mm, which seems reasonable

You can see much more about the FDC1004 at the E2E FDC1004 Frequently Asked Questions, which includes a comprehensive list of app notes & collateral, and an overview of the device theory of operation, apps and major device specs.

Regards,
John

0 Haresh Prajapati 9 months ago in reply to John Miller - Sensing

Prodigy 95 points

Thanks for the help

0 Haresh Prajapati 8 months ago in reply to Haresh Prajapati

Prodigy 95 points

Hello John Miller - Sensing

I made some design concept can you review it?

Please i cant send details here i need to send over mail or directly to you. Please share convivence way to do that.

0 John Miller - Sensing 8 months ago in reply to Haresh Prajapati

TI__Mastermind 40295 points

Haresh,

I will send a private message to you requesting "friend" status on E2E.
Accept and reply and we can exchange private messages.
In the mean-time I will close this thread, and we can re-open it later if needed.

Regards,
John

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FDC2214: Detection of human hand only