The flow through capacitor is a technology being developed as a fundamental new tool in water purification. This a solid state water purification device, whose technological relatives are in the electronics industry.
Capacitors are an electrical charge storage device.
Capacitance itself is a property of space whereby two conductors separated by a dielectric layer store charge. This was invented in 1746 by Pieter Van Musschenbroek., a professor of mathematics. Musschenbroek put water into a metal jar, covered with a cork, with a brass wire pushed through into the water. This whole contraption was hung up on insulating silk cords. Musschenbroek applied a charge through the brass wire into the water.