A system for filtering and treating waste generated or collected in the water of a fish pond. In one aspect, the gate insulating layer has a dielectric constant greater than the dielectric constant of silicon. The flexible sensed body includes a sensed portion and a connected portion connected with the ground plane where the sensed portion obliquely extends to above the key sensing cell such that the flexible sensed body and the key sensing cell jointly form a capacitor structure. Display and warning apparatus receive and record the analysis results from the detection device. The plural high-refractive areas comprises a first high-refractive area and plural second high-refractive area disposed on two sides of the high-refractive areas symmetrically, wherein the widths of the second high-refractive areas are the same and smaller than the width of the first high-refractive area. The invention also relates to a seat for a passenger vehicle and, more particularly, an aircraft, the pivotal rotation of which is provided with such a device.