Trap and release with the TEMPO. When the external NdFeB magnet is removed, the magnetic force disappears and the trapped cells can be released from the TEMPO. To trap and release cells, targeted cells are a) first trapped by passing the sample through the TEMPO filter with the external magnet in place, b) the trapped are washed by passing buffer solution, and c) the external magnet is removed and the trapped cells are released. d) Fluorescence image of cells on the TEMPO in bright field (BF) and green and red fluorescence channels during isolation of the cells and after release. The scale bar is 250 μm. e) The released beads were >95% pure from contamination of green beads, and this purity did not significantly change with additional layers n of TEMPO