Blood collection systems including a flexible filter

1. A blood filter comprising

a filter pad assembly comprising an inlet layer, an outlet layer, and at least one intermediate layer that comprises a fiber filter media,

a filter housing comprising a first flexible housing element overlying the inlet layer of the filter pad assembly and a second flexible housing element overlying the outlet layer of the filter pad assembly,

a peripheral seal formed by the application of radio frequency heating and pressure in a single step to join the first and second flexible housing elements directly to the filter pad assembly, the peripheral seal comprising a commingled melted matrix comprising material of the first and second housing elements and fiber filter media of the filter pad assembly,

an inlet port in the first housing element spaced from the peripheral seal for conveying blood to the filter pad assembly, and

an outlet port in the second housing element spaced from the peripheral seal for conveying blood from the filter pad assembly.

2. A blood filter according to claim 1

wherein the first and second housing elements include rims that are sealed together outwardly of the peripheral seal and outwardly of the peripheries of layers of the filter pad assembly.

3. A blood filter according to claim 1

wherein the inlet and outlet ports each include an axis that is generally parallel to a plane of the inlet layer and the outlet layer, respectively.

4. A blood filter according to claim 1

wherein the inlet layer comprises a prefilter.

5. A blood filter according to claim 4

wherein the prefilter comprises a fiber filter media.

6. A blood filter according to claim 1

wherein the at least one intermediate layer comprises a fiber filter media that removes leukocytes from blood.

7. A method of removing leukocytes from blood using the blood filter according to claim 1 , comprising the step conveying blood from a source through the filter pad assembly to remove leukocytes.

8. A blood collection system comprising

a container,

tubing communicating with the container, and

a blood filter according to claim 1 carried in line in the tubing.