Abstract:
A capacitive load cell apparatus (12) includes upper and lower capacitor plates (30, 28) and an intermediate dielectric (22) in the form of a synthetic knit spacer material having upper and lower fabric layers (22a, 22b) interconnected by an array of deflectable synthetic fibers (22c). When occupant weight is applied to the seat (10), the synthetic fibers (22c) deflect to locally reduce the separation between the upper and lower capacitor plates (30, 28), and the consequent change in capacitance is detected as a measure of the applied weight (14). The load cell (12) or just the dielectric (22) may be encased in a polymeric sheath (40, 42) to prevent intrusion of foreign matter, and a fluid such as silicone may be dispersed in woven dielectric (22).