Early breast cancer detection and diagnosis typically uses conventional mammogram screening followed by biopsy. This can be problematic since mammography can detect only highly calcified tumors greater than 1 cm in diameter. A micro-device was developed to identify and specifically collect tumor cells of low abundance (1 tumor cell among 10⁷ normal blood cells) from whole blood. By immobilizing anti-EpCAM antibodies on polymer micro-channel walls using chemical surface modification of the PMMA, breast cancer cells from the cell line MCF-7, which over-expresses EpCAM (Epithelial Cell Adhesion Molecule) on their surfaces, were caught by the strong binding affinity between the antibody and antigen. To validate the capture of the rare breast cancer cells, three fluorescence markers, each identified by a separate color, were used to reliably identify the cancer cells. The cancer cells were defined by DAPI+, CD45-and the cell membrane linker+ (FITC). White blood cells, which will interfere in the detection of the cancer cells, were identified by DAPI+ (blue), CD45+ (red), and the cell membrane linker+ (green). Three EpCAM/anti-EpCAM binding models were used to determine an optimal velocity, 2 mm/sec, which should guarantee the maximum binding and critical binding force as well as maximum throughput. At higher velocities, shear force (> 4.3 microdyne) will break existing bonds and prevent formation of new ones. Alternative design geometries were identified and the capture efficiency evaluated experimentally under different conditions. This detection micro-device can be assembled with other modular lab-on-a-chip components for follow- up gene and protein marker analysis.