US Patent 9182267 Capacitive level gauge

A fuel gauge (15) provided with an inner structural body (27) that is formed of an insulator; an outer structural body (23) that is formed of an insulator and disposed on the outer circumference side of the inner structural body (27) over the entire circumference thereof; an inner electrode (29) that is attached to an outer circumferential surface of the inner structural body (27); and an outer electrode (25) that is attached to an inner circumferential surface of the outer structural body (23). The fuel guage measures the capacitance between the inner electrode and the outer electrode and detects the level of fuel that exists between the inner electrode and the outer electrode. The outer structural body is provided with a plurality of outer through-holes (31) that allow electric charge to move from an outer circumferential surface thereof to the outer electrode.