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

Abstract

Microchannel bends of rectangular cross-section were fabricated on polymethylmethacrylate (PMMA) by hot embossing, with a range of channel widths from 55 m to 400 m. 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 m polystyrene microparticles using a simple microchannel bend structure. We have obtained approximately 100% efficiency for the combined separation and clog-free blocking of 10 m polystyrene microparticles using the above capillary flow behaviour in a modified microchannel bend structure.