A microfluidic device comprising: at least one sample inlet for receiving circulating tumor cells and other cells in a sample; at least one curvilinear channel through which the sample is caused to undergo migration along at least a partial Dean vortex to isolate the circulating tumor cells from the other cells; at least one sheath inlet coupled to the at least one curvilinear channel ; and at least one outlet configured to communicate with the curvilinear channel for providing the isolated circulating tumor cells, wherein the curvilinear channel is configured to provide a predetermined Force ratio greater than or equal to 2 based on a desired threshold cell size of 15-20 μm of the circulating tumor cells, the predetermined Force ratio being defined as a ratio of inertial lift force ( F L ) to Dean drag force ( F D ) , and wherein the predetermined Force ratio is further defined according to the equation: i F = F L / F D = 85.11 R C a C 3 D H 4 = 85.11 R C a C 3 h 4 , where i F is the Force ratio, R c is the average radius of curvature, a c is the cell size, D H is the hydraulic diameter and h is the curvilinear channel height, characterised in that the microfluidic device further comprises: a flow resistance channel comprising a series of semi-circular microchannels in a winding arrangement, wherein the at least one sample inlet is indirectly coupled to a start end of the at least one curvilinear channel via the flow resistance channel; and at least one damper chamber coupled to the at least one sheath inlet , wherein the flow resistance channel and the at least one damper chamber are configured to stabilize flow fluctuations within the at least one curvilinear channel . at least one sample inlet for receiving circulating tumor cells and other cells in a sample; at least one curvilinear channel through which the sample is caused to undergo migration along at least a partial Dean vortex to isolate the circulating tumor cells from the other cells; at least one sheath inlet coupled to the at least one curvilinear channel ; and at least one outlet configured to communicate with the curvilinear channel for providing the isolated circulating tumor cells, wherein the curvilinear channel is configured to provide a predetermined Force ratio greater than or equal to 2 based on a desired threshold cell size of 15-20 μm of the circulating tumor cells, the predetermined Force ratio being defined as a ratio of inertial lift force ( F L ) to Dean drag force ( F D ) , and wherein the predetermined Force ratio is further defined according to the equation: i F = F L / F D = 85.11 R C a C 3 D H 4 = 85.11 R C a C 3 h 4 , where i F is the Force ratio, R c is the average radius of curvature, a c is the cell size, D H is the hydraulic diameter and h is the curvilinear channel height, characterised in that the microfluidic device further comprises: a flow resistance channel comprising a series of semi-circular microchannels in a winding arrangement, wherein the at least one sample inlet is indirectly coupled to a start end of the at least one curvilinear channel via the flow resistance channel; and at least one damper chamber coupled to the at least one sheath inlet , wherein the flow resistance channel and the at least one damper chamber are configured to stabilize flow fluctuations within the at least one curvilinear channel . a flow resistance channel comprising a series of semi-circular microchannels in a winding arrangement, wherein the at least one sample inlet is indirectly coupled to a start end of the at least one curvilinear channel via the flow resistance channel; and at least one damper chamber coupled to the at least one sheath inlet , wherein the flow resistance channel and the at least one damper chamber are configured to stabilize flow fluctuations within the at least one curvilinear channel . <EOS>