Touch sensing design and water

[danvica]

Some times ago I developed a touch sensing wheel that works pretty well in dry enviroments.

You can see a picture and a small video:

Unluckly it was suppose to work in very wet conditions... and it didn't work, so I stopped the development.

Now I'd like to restart the project.

My question is: Have you experience of touch sensing pad/wheel in underwater system ?

Thanks.

 

[nandhu015]

I came across this one. May not be upto your requirement but i think helpful

ww1.microchip.com/downloads/en/AppNotes/01286A.pdf

 

[danvica]

Thanks, I already red some ANs (not this one,thanks again) from microchip but I would like so much to avoid the test-and-modify phase.

In the current project, the one shown in the movie, I used a QT1106 device from Quantum, now Atmel. Pretty simple to implement in dry conditions.

I hoped to get a water-resistant project just modifying this chipset but you are confirming me that, most probabily, the best choice is using a microcontroller and the right algorithm: I have to agree.

Still: anyone has any experience ?

Thanks.

 

[shurilo]

Hi,
I have experience with Atmel Touch design, and did evaluation for outside/raining conditions with the AT1070 eval. kit (AT42QT1070 device). In the 1070 you can actually play with thresholds to set it for rainy conditions so it will recognize touch of the finger even if there is water on the sensor. It was a button design, not a wheel like you have on yours, but would still work on wheel I assume.
With the wet conditions I think you should use the device that has this internal register settings for sensitivity, as opposed to the non-register settings ones where you can only change the resistor to adjust the sensitivity.
The 1070 kit is great for this purpose as proof of concept, and easy to use.

 

[danvica]

Thanks for the suggestions, I'll study the Atmel docs more carefully.