I-Corps: Micro-scale computed axial lithography for 3D fabrication in challenging materials

I-Corps项目更广泛的影响/商业潜力是开发微型轴向光刻增材制造工艺。包括玻璃和陶瓷在内的无机材料具有耐高温和耐化学性、高刚度和高强度以及生物惰性。由于原材料的脆性，复杂几何形状的制造具有挑战性，并且从历史上看，一直由减法加工操作（包括铣削，磨削和化学蚀刻）主导。然而，随着技术进步激发了具有独特3D形态的定制应用特定器件的制造，传统的制造方法本质上受到材料去除单元工艺的限制。该技术旨在快速生产具有相对光滑表面的3D微结构。这可能用于制造具有高光学清晰度，惰性和适合挑战性化学环境的微流体装置（包括微混合器）。此外，所提出的技术可以在小批量生产中实现具有多个流体通道深度的定制几何形状。这种定制水平是不容易实现传统的短期制造方法，如湿化学蚀刻，或注塑成型。例如，该技术可用于快速精确地打印定制牙冠，其中每个牙冠必须是独特的，并根据患者的牙齿形状量身定制。所提出的技术还可应用于生产用于注射成型工艺的模具镶件。在未来，这项技术可能会降低制造成本，并为包括牙科、医疗和半导体在内的广泛行业定制高精度零件。这个I-Corps项目是基于一种称为计算轴向光刻（CAL）的增材制造技术的发展。提出的技术是一个体积，光为基础，微尺度光聚合方法在概念上类似于计算机断层扫描的逆。零件是通过将一个容器的光响应材料暴露在从多个角度计算的光模式下打印出来的，并且集成的光剂量光聚合成规定的3D几何形状。该工艺目前能够在几秒钟内定义硅玻璃纳米复合材料中具有50 μ m正特征尺寸和150 μ m内部通道直径的几何形状。经过热后处理后，可以获得具有高光学透明度和纳米级表面粗糙度的复杂固体硅玻璃几何形状。此外，用于直接打印成有机光聚合物树脂的工艺，以及用于其他特殊应用的陶瓷纳米复合材料的工艺正在开发中。与工业上建立的逐层方法相比，该技术的优点包括其更高的吞吐量，更低的表面粗糙度，以及消除浪费的固体打印支撑结构。较低的表面粗糙度使得该工艺对美学清晰度很重要的应用具有潜在的吸引力，并可用于生产定制的微光学元件。断裂测试结果表明，较低的粗糙度导致微cal打印部件的机械强度分布比逐层打印部件更紧密。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

The broader impact/commercial potential of this I-Corps project is the development of a microscale computed axial lithography additive manufacturing process. Inorganic materials including glasses and ceramics have high temperature and chemical resistance, high stiffness and strength, and biological inertness. Due to the brittleness of the raw material, manufacturing of complex geometries is challenging and, historically, has been dominated by subtractive machining operations including milling, grinding, and chemical etching. However, as technological advances motivate the manufacture of customized application-specific devices with unique 3D morphologies, the conventional fabrication methods are inherently limited by material removal unit processes. The proposed technology is designed for rapid production of 3D microstructures with relatively smooth surfaces. This may be used in the manufacture of microfluidic devices (including micromixers) with high optical clarity, inertness, and suitability for challenging chemical environments. In addition, the proposed technology may achieve customized geometries with multiple fluidic channel depths in low-volume production. This level of customization is not easily achievable with conventional short-run fabrication methods such as wet chemical etching, or injection molding. For example, the technology may be used to enable the rapid and precise printing of customized dental crowns, where each crown must be unique and tailored to fit the shape of the patient’s teeth. The proposed technology also may be applied to producing mold inserts for injection molding processes. In the future, this technology may reduce manufacturing costs and enable the customization of high-precision parts for a wide range of industries including dental, medical, and semiconductor.This I-Corps project is based on the development of an additive manufacturing technology called computed axial lithography (CAL). The proposed technology is a volumetric, light-based, micro-scale photopolymerization method conceptually analogous to the inverse of computed tomography. Parts are printed by exposing a container of photoresponsive material to computed light patterns from many angles and the integrated light dose photopolymerizes a prescribed 3D geometry. The process is currently capable of defining geometries with 50 µm positive feature size and 150 µm internal channel diameters in silica glass nanocomposite materials within a few seconds. After thermal post-processing, complex solid silica glass geometries with high optical transparency and nanometer-level surface roughness may be achieved. In addition, the process by be used for printing directly into organic photopolymer resins, and processes for other ceramic nanocomposites with specialized applications are under development. The merits of this technique over industrially established layer-by-layer methods include its higher throughput, lower surface roughness, and elimination of wasteful solid print-supporting structures. The lower surface roughness makes the process potentially attractive for applications where aesthetic clarity is important, and for producing custom micro-optical components. Fracture testing results indicate that the lower roughness results in a tighter distribution of mechanical strength in micro-CAL-printed components than in layer-by-layer-printed parts.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.