Patent ID: 8757156

Claim:
A face mask that comprises: a mask body adapted to fit over at least the nose and mouth of a person to help define an interior gas space when worn; and a unidirectional valve that permits fluid communication between the interior gas space and an exterior gas space, wherein the unidirectional valve comprises: a base attached to the mask body, the base comprising two or more openings through which gas may pass between the interior gas space and the exterior gas space, wherein each opening of the two or more openings is surrounded by a seal surface that extends around the opening; a stationary diaphragm positioned on the base, wherein the diaphragm extends over the two or more openings and their respective seal surfaces; two or more valve flaps formed within the diaphragm, wherein each valve flap of the two or more valve flaps is located over one of the two or more openings, and wherein each valve flap of the two or more valve flaps comprises a boundary slot formed through the diaphragm and a hinge along which the valve flap is attached to the diaphragm, wherein the boundary slot defines a free edge of the valve flap that extends from a first end to a second end and wherein the hinge extends between the first end and the second end of the free edge of the valve flap; and wherein each valve flap of the two or more valve flaps exhibits a cantilever bend ratio of 0.0050 or less and has a thickness of 10 to 2000 micrometers and comprises a closed position in which the valve flap contacts the seal surface and remains in contact with seal surface regardless of the orientation of the unidirectional valve, and wherein the valve flap also comprises an open position in which at least a portion of the valve flap is lifted off of the seal surface such that gas may pass between the interior gas space and the exterior gas space.