Seat occupant weight sensor, method for making and system therefor

An occupant weight sensor (1) for placement between a frame (7) fixed to the chassis of a vehicle and a second frame (8) supporting a vehicle seat has a sense element having a first body (12, 22, 28, 34, 50, 62, 64, 68) formed with a planar sense surface on which are mounted piezoresistors electrically connected in a Wheatstone bridge configuration. A post (12a, 22c, 28c, 34e, 50b, 62a, 64a, 68b) extends outwardly from the first body for attachment to the first frame. A second body is formed with a force transfer portion (14a, 24g, 30d, 36b, 52a, 70a) permanently attached to the first body along an outer periphery circumscribing the sense surface. The piezoresistors are electrically connected to conditioning electronics received in a chamber formed between the two bodies. The effects of parasitic loads on the sense element are minimized by selected placement of the piezoresistors on the sense surface. Several variations are disclosed for attaching the sensor to the first and second frames and both longitudinally and laterally extending electrical connectors are shown.