The most basic FSR® (Force-Sensing Resistor) consists of two membranes separated by a thin air gap, which is maintained by a spacer around the edges and by the rigidity of the two membranes. One of the membranes has two sets of fingers which are interdigitated and electrically distinct; each set connects to one trace on the tail. The other membrane is coated with FSR ink. When the two layers are pressed together, the FSR ink shorts the two traces together with a resistance that depends on applied force. The 4-Zone FSR used in MicroModule is a combo of four basic FSR’s arranged in a North, South, East, and West pattern. Each zone interpenetrates into two zones on either side of it. This overlapping of the zones allows Interlink to determine how much force is in each zone relative to the others. Once the relative force in each zone is known, the direction and speed of the mouse pointer can be determined.