Multi-layer filtration device

A filter device assembly for capturing embolic particles in a blood flow in a body vessel, the device comprising:

• a structure having a frame with a predetermined shape, and a distal and proximal portion;
• the frame being configured to move between an expanded state for engagement with the body vessel and a collapsed state for delivery and retrieval, the structure having frame struts extending from the proximal portion to the distal portion longitudinally along an outside diameter of the filter device assembly, the frame struts proximally merging in the proximal portion toward a reduced diameter and configured to be coupled to a removal device;
• and
• at least a first filter member and a second filter member, the second filter member being arranged distally from the first filter member and configured to be placed downstream from the first filter member with respect to the blood flow, each filter member having a proximal part and a distal part, the proximal part circumferentially attached to the frame struts;
• the distal part of the first filter member closed such that the first filter member forms a first annulus chamber having porosity P1 and the distal part of the second filter member closed such that the second filter member forms a second annulus chamber having porosity P2;
• wherein the magnitude of the porosity for the first and second filter members follows the relationship P1>P2;
• wherein the first and second filter members are configured in the expanded state to allow blood to flow there through and to capture emboli in the annulus chambers.