To observe the cross-sectional imag

To observe the cross-sectional images of the enclosed circular microchannels, which could be achieved by the thermal bonding of two microinjection-molded plates, the center area of the bonded microfluidic chip prototype was carefully sliced by a low-speed diamond saw (IsoMet,BUEHLER) as shown in Fig. 8a. Figure 8b and c shows the tilted SEM images of the sliced face with the circular microchannels of 500 and 50 lm diameters, respectively.From the SEM images, it was found that the present thermal bonding produced perfectly enclosed circular microchannels. Although the sliced surface was not clean and some burrs or residues generated during the slicing remained in the larger microchannel, the enclosed microchannels were successfully obtained. It might be noted that the round edges in the replicated open microchannel were minimized in the final structure as the bonding process produced a slight thermal deformation at the bonded interface.