I am currently working on a project in the field of tangible user interface. I am developing a game in which a pressure sensor squeezable ball is the input controller. I am done with the game. Now I need to design a squeeze ball.

My next aim is to find out the number of sensors required, their ideal locations in the ball so that user's fingers are utilized to the maximum while playing the game & maximum forces are applied to the sensor locations.

So I would like to find out theoretically the maximum pressure areas when we squeeze a ball. I believe it's under the finger tips. But how do I prove it theoretically by writing equations involving force or displacement? I am using a foam ball & the squeeze pattern is using the fingers & palm of the hand.

Any input to this will be highly appreciated. Thanks in advance.