Production of high‐aspect‐ratio rectangular‐lumen microtube by gas‐assisted microextrusion

Flexible polymeric microtubes with rectangular‐lumen are useful in chemical and bioengineering. However, improving the aspect ratio of the rectangular lumen is still a tough task. In this study, numerical simulations are carried out to study the influences of the processing parameters and the design of the extrusion die on the aspect ratio of the rectangular microchannels. Increasing the length of the inner die and reducing its width are critical to improving the aspect ratio of channels. The pressure difference is also important for controlling the sizes and shapes of channels. A linear mathematical relationship is built between the aspect ratio of channels and processing parameters and the sizes of the die. According to the simulating results, the geometry of the inner die is optimized and manufactured experimentally. The flexible rectangular microtubes are produced with well‐controlled channel sizes. The highest aspect ratio of the channel we achieve is 87.