A microfluidic device comprising: at least one sample inlet (808a, 808b) for receiving circulating tumor cells and other cells in a sample; at least one curvilinear channel (804a, 804b) 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 (804a, 804b); and at least one outlet (812, 814) 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 (808a, 808b) is indirectly coupled to a start end of the at least one curvilinear channel (804a, 804b) via the flow resistance channel; and at least one damper chamber (807a, 807b) coupled to the at least one sheath inlet, wherein the flow resistance channel and the at least one damper chamber (807a, 807b) are configured to stabilize flow fluctuations within the at least one curvilinear channel (804a, 804b). at least one sample inlet (808a, 808b) for receiving circulating tumor cells and other cells in a sample; at least one curvilinear channel (804a, 804b) 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 (804a, 804b); and at least one outlet (812, 814) 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 (808a, 808b) is indirectly coupled to a start end of the at least one curvilinear channel (804a, 804b) via the flow resistance channel; and at least one damper chamber (807a, 807b) coupled to the at least one sheath inlet, wherein the flow resistance channel and the at least one damper chamber (807a, 807b) are configured to stabilize flow fluctuations within the at least one curvilinear channel (804a, 804b). a flow resistance channel comprising a series of semi-circular microchannels in a winding arrangement, wherein the at least one sample inlet (808a, 808b) is indirectly coupled to a start end of the at least one curvilinear channel (804a, 804b) via the flow resistance channel; and at least one damper chamber (807a, 807b) coupled to the at least one sheath inlet, wherein the flow resistance channel and the at least one damper chamber (807a, 807b) are configured to stabilize flow fluctuations within the at least one curvilinear channel (804a, 804b).