Micromilling is a flexible, inexpensive and rapid prototyping technique for polymer microfluidic devices. However, the applications of microfluidic devices fabricated by micromilling have been compromised by their poor surface quality. In this study, we demonstrated a gas-blowing-assisted (GBA) polydimethylsiloxane (PDMS) coating that is used to reduce the surface roughness of micromilled channels, yielding optical grade channel walls while simultaneously offering high flexibility in channel dimensions and morphology by controlling the coating parameters. In this method, a thin layer of PDMS is coated on the engraved substrate, and then a computer numerical control (CNC)-guided gas-blowing is used to selectively remove surplus PDMS prepolymer in channels, which results in a thin residual and smooth PDMS coating on the walls of channels. With this GBA PDMS coating, the channel surface roughness of below 8 nm could be achieved without the need of advanced polishing equipment or procedures. Furthermore, this method has the capability to fabricate non-rectangular microchannels with different shapes in cross-section depending on the process parameters, which benefits microvascular research and tissue engineering.

微铣削是一种用于聚合物微流控设备的灵活，廉价且快速的原型技术。然而，通过微研磨制造的微流体装置的应用由于其不良的表面质量而受到损害。在这项研究中，我们展示了一种气体辅助（GBA）聚二甲基硅氧烷（PDMS）涂层，该涂层可用于减少微铣削通道的表面粗糙度，产生光学级通道壁，同时通过控制通道尺寸和形态来提供高灵活性涂层参数。在这种方法中，将PDMS薄层涂覆在雕刻的基材上，然后使用计算机数控（CNC）引导的吹气有选择地去除通道中多余的PDMS预聚物，这将导致残留的薄而光滑的PDMS通道壁上的涂层。使用这种GBA PDMS涂层，无需先进的抛光设备或程序即可实现低于8 nm的通道表面粗糙度。此外，该方法具有根据工艺参数制造横截面形状不同的非矩形微通道的能力，这有利于微血管研究和组织工程。