CONVEX microfluidic devices: a new microscale agile manufacturing pipeline for material extrusion additive manufacturing
CONVEX microfluidic devices: a new microscale agile manufacturing pipeline for material extrusion additive manufacturing
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发表时间：
2022
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通讯作者：
Amirpasha Moetazedian;Vahid Nasrollahi;A. Candeo;Liam C Cox;M. Liam;Grover;G. Poologasundarampillai
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作者：
Amirpasha Moetazedian;Vahid Nasrollahi;A. Candeo;Liam C Cox;M. Liam;Grover;G. Poologasundarampillai
本研究首次报道了材料挤压增材制造（MEAM）中基于连续变化挤压（CONVEX）挤压长丝的复杂微流控装置的制造。一系列复杂的几何形状和通道宽度（100-400 μ m）是通过直接GCode脚本开发的，包括六边形、菱形、之字形和变宽之字形（v字形）的被动混合器和流体动力聚焦组件。对于每个设计，随着喷嘴在X或Y方向上的移动，沉积一层长丝，同时控制挤出量和打印速度，以实现无缝的Y或交叉结通道。新型的v型之字形工具路径设计需要沿路径以不同的打印速度沉积，以在预定位置创建可变宽度（喷嘴直径的200%）的之字形结构。在嵌入聚二甲基硅氧烷（PDMS）之前，将被动混合区选择性地暴露于丙酮中10 s，以降低通道的表面粗糙度。研究人员对设备结构和流体流动特性进行了研究，以了解制造几何形状对性能的影响。显微分析表明，与MEAM零件的典型值相比，新型制造和化学处理的结合使所有设计的表面粗糙度降低了两个数量级。通道宽度为400µm的微流控装置在1 ~ 1000µl范围内进行了流体混合动力学测量。最小-1。v型之字形混合器在两种液体沿流动方向接触仅15毫米后，无论流量如何，都能迅速实现完全混合。相比之下，当流量从50µl增加到100µl时，其他设计的混合性能逐渐下降。最小-1，突出几何的重要效果。结果表明，v型之字形的变宽度微尺度修饰通过促进通道内流体流动方向的变化来增强混合，与传统之字形设计相比，可以提供更好的高流速。这种制造策略的弹性和稳健性通过推动AM的边界来证明，以生产具有高重复性的横截面为100 × 100 μ m的通道。案例研究表明，新开发的微流控装置适用于广泛的微流控应用，包括流控芯片液滴发生器和流动聚焦打印头功能，以精确控制多材料流体鞘的宽度。±0.03µm)，两个方向之间仅相差6.4%。这些结果证明了丙酮处理如何通过去除两个方向上的纹理来降低MEAM通道的表面粗糙度，从而产生一个平坦的无特征的表面形貌，与注射成型[41]产生的表面形貌相当。与文献中报道的类似MEAM样品相比，本研究计算的表面粗糙度显著降低（高达98.7%）。
This study is the first to report the fabrication of complex microfluidic devices based on CONtinuously Varied EXtrusion (CONVEX) of extruded filament in material extrusion additive manufacturing (MEAM). A range of complex geometries and channel widths (100–400 µm) were developed by direct GCode scripting including passive mixers of hexagonal, diamond, zigzag and variable-width zigzag (V-zigzag) and hydrodynamic flow focusing components. For each design, a single layer of filament was deposited as the nozzle moved in the X or Y direction, while simultaneously controlling the extrusion volume and printing speed to achieve seamless Y- or cross-junction channels. The novel V-zigzag toolpath design required deposition at varying printing speed along the path, to create the zigzag structure with variable width (200% of nozzle diameter) at pre-determined locations. The passive mixer regions were selectively exposed to acetone for 10 s to reduce the surface roughness of channels before embedding in the polydimethylsiloxane (PDMS). Device structural and fluid flow properties were investigated to generate insights on the impact of manufactured geometry on performance. Microscopic analysis showed the combination of novel manufacturing and chemical treatment reduced the surface roughness of all designs by two orders of magnitude compared to typical values for MEAM parts. Fluid mixing dynamics of microfluidic devices with 400 µm channel widths were measured from 1–1000 µl.min -1 . V-zigzag mixers achieved complete mixing rapidly irrespective of flow rates after only 15 mm following two liquids coming into contact along the flow direction. By contrast, the mixing performance progressively decreased for the other designs as the flow rate increased from 50 to 100 µl.min -1 , highlighting the important effect of geometry. It was established that the variable-width microscale modification in V-zigzag enhances mixing by promoting directional changes in fluid flow within the channel, affording better high flow rates compared to a conventional zigzag design. The resilience and robustness of this manufacturing strategy is demonstrated by pushing the boundaries in AM to produce channels with cross-section of 100 × 100 µm with high repeatability. Case studies demonstrated the applicability of the newly developed microfluidic devices for a wide range of microfluidic applications including fluidic-chip droplet generator and flow focusing printhead capabilities to precisely control the width of multi-material fluid sheaths. ± 0.03 µm, respectively), with only 6.4% difference between the two directions. These results demonstrate how acetone treatment reduces surface roughness of the MEAM channels by removing the texture in both directions, creating a flat featureless surface topography, comparable to those produced by injection moulding [41]. The calculated surface roughness in this study was impressively lower (up to 98.7% reduction) than the values reported in the literature for similar MEAM specimens [11].