Effect of the inclined angle of micro-milling tool on the fabrication of the microfluidic channel

Abstract

Abstract Micro-milling is a common processing method for fabricating microfluidic chips or other micro products with high processing accuracy and low cost, suitable for mass production. The main concern of micro-milling is the surface roughness of the machined surface. However, the general study of the surface roughness of micro-milling can only find that only a small range of surface roughness can be obtained by changing the processing parameters. It is very difficult to obtain a specific roughness. In the process of micro-milling with end mills, due to the structural characteristics of the tool tip, the inclination angle of the tool will have a significant impact on the bottom surface of the machined channels. In this work, the influence of tool inclination on the surface roughness of machining was studied through the machining tests of inclined micro-milling on a poly(methyl methacrylate) (PMMA) surface, and it was proposed to realize the control of the machined surface roughness by inclined micro-milling. In addition, a theoretical model considering tool inclination was established to calculate the surface roughness of the machined bottom obtained by inclined micro-milling. The experimental results are consistent with the theoretical model results in the lower speed range. Afterwards, the polydimethylsiloxane (PDMS) is used to replicate the microchannel machined on the PMMA surface, and the microfluidic chips were prepared to control the fluid flow in the channel by adjusting the roughness of the bottom of the channel. Results show that the smoother channel will flow first under the same flow pressure. The study offers a new idea of surface roughness control, which can be applied to flow control in microfluidic chips.