Fluid mixing apparatus such as a ventilator

An apparatus such as a fluid mixer, suitable for use with a respirator, including a venturi nozzle for flow of a pressure-controlled fluid; an ambient fluid aperture in fluid communication with the venturi nozzle; a fluid port; a pressure force multiplier in fluid communication with the fluid port; and a valve moveable relative to the venturi nozzle between a start flow position and a stop flow position; where the pressure force multiplier is configured such that fluid forced into the fluid port actuates the valve relative to the venturi nozzle; and where the pressure force multiplier is configured such that fluid withdrawn from the fluid port actuates the valve relative to the venturi nozzle, further comprising an active filter that comprises an energy harvesting system and at least one filter medium, wherein the energy harvesting system generates electricity to induce a static charge in the at least one filter medium.