for example it can remove difficult-to-detect viruses:
http://money.cnn.com/video/technology/2013/08/16/t-ts-spleen-on-a-chip.cnnmoney/index.html?iid=V_Top
http://money.cnn.com/video/technology/2013/08/16/t-ts-spleen-on-a-chip.cnnmoney/index.html?iid=V_Top