A force sensing membrane comprises (a) a first conductor that is movable
toward a second conductor; (b) a second conductor; and (c) a composite
material disposed between the first and second conductors for
electrically connecting the first and second conductors under application
of sufficient pressure therebetween; and (d) means for measuring dynamic
electrical response across the force sensing membrane, the composite
material comprising conductive particles at least partially embedded in
an elastomeric layer, the conductive particles having no relative
orientation and being disposed so that substantially all electrical
connections made between the first and second conductors are in the z
direction, and the elastomeric layer being capable of returning to
substantially its original dimensions on release of pressure.