Abstract: A slotted microfilter is coated with a phase changeable material having a hydrophobic state under a first temperature and a hydrophilic state under a second temperature. An example coating material is poly(N-isopropylacrylamide) (“PIPAAm”). The microfilter can be controlled to switch between a capture state where circulating tumor cells are captured by the microfilter and a release state, where viable tumor cells are released from capture for analysis, e.g., single cell phenotypic and genomic analysis, or for ex vivo culture growth.