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

这个I-Corps项目的更广泛的影响/商业潜力是开发微尺度计算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，并且历史上一直由减材加工操作（包括铣削、研磨和化学蚀刻）主导。 然而，随着技术进步促使制造具有独特3D形态的定制专用设备，传统的制造方法固有地受到材料去除单元工艺的限制。 所提出的技术旨在快速生产具有相对光滑表面的3D微结构。 这可用于制造具有高光学透明度、惰性和对挑战性化学环境的适用性的微流体装置（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。这种程度的定制是不容易实现的传统的短期制造方法，如湿化学蚀刻，或注塑成型。例如，该技术可用于实现定制牙冠的快速和精确打印，其中每个牙冠必须是唯一的并且被定制以适合患者牙齿的形状。 所提出的技术还可以应用于生产用于注射成型工艺的模具插入件。未来，该技术可以降低制造成本，并为牙科、医疗、半导体等广泛行业定制高精度零件。I-Corps的项目是基于开发一种称为计算轴向光刻（CAL）的增材制造技术。 所提出的技术是一种体积，基于光的，微尺度的光聚合方法，概念上类似于计算机断层扫描的逆。通过将光敏材料的容器暴露于从多个角度计算的光图案来打印部件，并且集成的光剂量光聚合指定的3D几何形状。 该工艺目前能够在几秒钟内在二氧化硅玻璃纳米复合材料中定义具有50 µm正特征尺寸和150 µm内部通道直径的几何形状。在热后处理之后，可以实现具有高光学透明度和纳米级表面粗糙度的复杂固体二氧化硅玻璃几何形状。此外，该工艺可用于直接印刷到有机光聚合物树脂中，以及用于具有特殊应用的其他陶瓷纳米复合材料的工艺正在开发中。 这种技术相对于工业上建立的逐层方法的优点包括其更高的吞吐量、更低的表面粗糙度和消除浪费的固体印刷支撑结构。较低的表面粗糙度使得该工艺对于美学清晰度很重要的应用以及用于生产定制的微光学元件具有潜在的吸引力。断裂测试结果表明，与逐层打印零件相比，较低的粗糙度使微型CAL打印部件的机械强度分布更紧密。该奖项反映了NSF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.