Measure the pressure on a push button

[Universe104]

Dear All,

I am looking for a way to measure the pressure on a push button when it is pressed. I intend to save it in the flash of a microcontroller.

Kindly let me know if you know of any suitable device.

Thanks,

 

[KlausST]

Hi,

Please clarify:

I am looking for a way to measure the pressure on a push button when it is pressed

Reading this I thought you need a mechanical test construction.
But mind that there will be not only one "pressure" or "force", it may be a complete diagram, depending on what pushbutton you are talking about.
Many pushbutton have metal domes, this creates some hyteresis, then you have at least two forces: The "make" force and the "break" force.
(indeed there may be at least 4 values: before_make, after_make, before_release and after_release)
Pushbutton without metal domes will vary their "make force" with time, and environment. There will be oxide on the contacts and the thicker (older) the oxide you need more force to break through.

I intend to save it in the flash of a microcontroller.

This now is a completely different task.

***
I think we need more information.
What value or information are you interested in?
* is the pushbutton mounted on a PCB or not? Do you have access to the connection?
* what mechanical environment do you have? How to generate the force (electrically, air pressure...) is the mechanical construction very stiff or very weak and so on...

Maybe you can tell what´s the use of this all.

Klaus

 

[Universe104]

Thanks for your reply!

Hi,

Please clarify:

But mind that there will be not only one "pressure" or "force", it may be a complete diagram, depending on what pushbutton you are talking about.
Many pushbutton have metal domes, this creates some hyteresis, then you have at least two forces: The "make" force and the "break" force.
(indeed there may be at least 4 values: before_make, after_make, before_release and after_release)
Pushbutton without metal domes will vary their "make force" with time, and environment. There will be oxide on the contacts and the thicker (older) the oxide you need more force to break through.

Klaus

I am only looking for the make force, when the button is pressed using fingers. The button is connected to an input pin of a microcontroller and grounds the pin when pressed.

***
I think we need more information.
What value or information are you interested in?
* is the pushbutton mounted on a PCB or not? Do you have access to the connection?
* what mechanical environment do you have? How to generate the force (electrically, air pressure...) is the mechanical construction very stiff or very weak and so on...
Klaus

The button is mounted on a PCB and I think it is stiff enough.

I found a suitable strain gauge, which might be useful.
https://www.sparkfun.com/products/10245

 

[c_mitra]

You may use a pressure sensitive conducting rubber mat that has resistance depending on the force or pressure.

 

[andre_luis]

Depending on the button kind, the result obtained by this measurement may be meaningless. Buttons have an internal spring where once the applied force exceeds its deflection constant the next course will be that of an impact, generating a force impulse. Graphically, would yield a linear curve at beginning and a step after that. It's not clear exactly what you want to achieve nor the purpose, which would help you think of a more appropriate solution, if there is one.