Experimental study on capillary flow through polymer microchannel bends for microfluidic applications

Microchannel bends of rectangular cross-section were fabricated on polymethylmethacrylate (PMMA) by hot embossing, with a range of channel widths from 55 µm to 400 µm. The capillary movement of the interface between air and dyed water through the microchannels was recorded and analysed. The microfluidic flow behaviour as a function of the channel aspect ratio was studied. The evaluated Reynolds number was always less than 1.0 in each channel of every device. The air–water interface velocity in the devices was proportional to the channel aspect ratio. The air–water interface velocity shows a prominent increase at 90° separation angle. We observed an increasing trend of the air–water interface velocity with increasing channel aspect ratio. We have studied the separation of 10 µm polystyrene microparticles using a simple microchannel bend structure. We have obtained approximately 100% efficiency for the combined separation and clog-free blocking of 10 µm polystyrene microparticles using the above capillary flow behaviour in a modified microchannel bend structure.