Can you investigate sourcing QTC “buttons” for use as a touch & force sensor?
A description of the technology is here: http://www.tep.org.uk/old_stuff/millennium_smart_qtc.html
An example of its use, on a robotic finger is here (the QTC sensor is discussed abotu 1/2 way down): http://letsmakerobots.com/node/14041
Here is a link to a former source, that now shows the product as discontinued: http://www.maplin.co.uk/DiscontinuedModule.aspx?ModuleNo=44202
This product/technology has amazing possibilities and virtual no availability. Perhaps it is more readily available in your market.