Sensor that measures surface area contact

Hello, I have been looking all over for this with no luck. I am trying to find a sensor that just measures how much contact a finger has with a surface..not the pressure... just the amount of area in fine detail the finger has touched. Does anyone have any ideas??? Thanks

Define "fine detail".

jremington: Define "fine detail".

as fine as I can get, but I can't seem to find anything that would do this in even rough detail.

You might be able to use an image from a fingerprint scanner to measure contact area.

What sort of surface? It seems improbable that such a sensor exists.

You will have to fabricate one, either by analysis of an image ( not very easy on an Arduino ) or from something like a matrix of contacts underneath the finger.