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/商业潜力是开发一种微型计算轴向光刻添加剂制造工艺。包括玻璃和陶瓷在内的无机材料具有耐高温、耐化学腐蚀、高硬度和高强度以及生物惰性等特点。由于原材料的脆性，复杂几何形状的制造具有挑战性，历史上一直由包括铣削、研磨和化学蚀刻在内的减法加工操作主导。然而，由于技术进步推动了具有独特3D形态的定制专用器件的制造，传统的制造方法固有地受到材料去除单元工艺的限制。该技术旨在快速制造表面相对光滑的三维微结构。这可用于制造具有高光学清晰度、惰性和对苛刻化学环境的适应性的微流控器件(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射流通道深度的定制几何形状。使用传统的短期制造方法，如湿法化学蚀刻或注塑成型，很难实现这种程度的定制。例如，这项技术可以用于快速而精确地打印定制的牙冠，其中每个牙冠必须是独一无二的，并根据患者的牙齿形状进行定制。所提出的技术也可应用于生产注塑成型过程中的模具插件。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部件。这个i-Corps项目基于一种名为计算机轴向光刻(CAL)的附加制造技术的开发。所提出的技术是一种体积、基于光的、微尺度的光聚合方法，在概念上类似于计算机断层扫描的逆。零件是通过将光响应材料的容器暴露在从多个角度计算的光图案中来打印的，并且集成的光剂量光聚合了规定的3D几何形状。该工艺目前能够在几秒钟内确定石英玻璃纳米复合材料中具有50微米正特征尺寸和150微米内部通道直径的几何形状。经过热后处理后，可以得到光学透明度高、表面粗糙度达到纳米级的复杂固体二氧化硅玻璃。此外，该工艺可直接用于印刷有机光致聚合物树脂，其他具有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，该技术的优点包括更高的产量，更低的表面粗糙度，以及消除了浪费的固体印刷支撑结构。较低的表面粗糙度使该工艺具有潜在的吸引力，适用于美学清晰度很重要的应用，以及生产定制的微型光学元件。断裂测试结果表明，较低的粗糙度导致微CAL印刷部件中的机械强度比逐层印刷部件中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智力优势和更广泛的影响审查标准进行评估，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.