Microfabricated electrolysis pump system for isolating rare cells in blood

An integrated system for immunomagnetic separation of rare cells from blood is presented. A micromachined device was fabricated by bonding silicon die with etched structures to a glass cover plate on which electrodes are defined. Electrolytic generation of gas from 0.50 M KNO3 (aqueous) provided pumping actuation for a device that performed the capture and purification of rare cells spiked into a 7.5 mul reconstituted blood sample. The system consisted of two pumps, a sample and a wash buffer meander reservoir, and a main channel for magnetic field trapping of rare cells captured by antibody-coated magnetic beads. A maximum pumping rate of 1.4 +/- 0.1 mul min(-1) was obtained at a current of 180 muA, and the maximum blood sample volume delivered to the capture bed was 6.5-7 mul. The trapped cells could be washed with the buffer from the second pump and then delivered to the exit port of the chip after removing the magnetic field.