旋转尖基微切削加工制备的无毛刺PMMA微通道微流控芯片快速成型

AbstractCost-effective and rapid prototyping of microfluidic chips has become increasingly possible. However, micromilling, as a popular method for the fabrication of a microfluidic channel, shows no advantage when dealing with a microchannel with a width of less than 50 μm. In this paper, a mimic of the micromilling method, revolving tip-based micro-cutting, was employed to achieve direct writing of a microchannel on polymethylmethacrylate (PMMA) with a width ranging from several micrometres to hundreds of micrometres. A piezoelectric actuator was used to revolve a three-sided nanoindenter instead of a spindle to rotate a mill. Based on the characteristics of revolving cutting, optimization analysis, which focuses on burr formation and surface quality, was performed, and the obtained microchannels exhibited burr-free sides with a bottom surface roughness of Sa = 19 nm. To verify the effectiveness of the proposed micromachining method, two low-cost preparation processes for a microfluidic chip with a fabricated PMMA microchannel were demonstrated. One was directly bonding the fabricated PMMA sheet to another sheet with UV-assisted solvent bonding, where it was concluded that the burr-free sides of the channel played a critical effect on bonding the shallow microchannel. The other was using the fabricated PMMA as a mould to transfer the microchannel to a casted polydimethylsiloxane (PDMS) chip. Finally, a fabricated micro-cross channel was tested to generate a microdroplet, and it was observed that the size and generation rate of microdroplets were controllable.