Detecting heterogenic tumor cells that are traveling in our body through blood 
stream for the tumor metastasis is one way for cancer prognosis. Due to the 
heterogeneity of circulating tumor cells (CTCs), further identification of tumor 
cell types should be accompanied with CTCs isolation from blood cells in 
peripheral blood sample. Both negative enrichment and recollection of isolated 
CTCs are required in the downstream analysis, which are time-consuming, 
labor-intensive, and massive equipment required. To solve these limitations, we 
have developed a simple and disposable spiral shape microfluidic channel that 
can separate all CTCs from blood cells, and at the same time, can identify the 
types of CTCs based on epithelial cell adhesion molecule (EpCAM) expression 
level. Two different types of tumor cells, MCF-7 and MDA-MB-231, both from the 
same origin of breast carcinoma cells, were used to demonstrate the 
functionality of the developed system. The spiral channel system could capture 
the EpCAM positive and negative CTCs with 96.3% and 81.2% purity, respectively, 
while both EpCAM positive and negative CTCs were differently positioned along 
the microfluidic channel. The average selectivity of EpCAM positive and negative 
CTCs is 6.1:4.8. In addition, the throughput of the system was optimized at a 
sample flow rate of 150µl/min. The developed system successfully demonstrated 
its potential to identify biomarkers, including EpCAM, for detecting the 
heterogenic CTCs.