3D打印新技术将不透明树脂制成物体

瑞士洛桑联邦理工学院（EPFL）的一个工程师团队开发出一种3D打印方法，可在数秒钟内用光将不透明的树脂制成物体。这一突破或在生物医学行业有良好应用前景，例如可用于制造人工动脉。相关研究近日发表在《先进科学》杂志上。

早在2017年，EPFL工程学院应用光子器件实验室（LAPD）的工程师们就设计了一种能够几乎瞬间制造物体的3D打印机。5年后，该团队改进了他们的打印设备和方法，可生产出由不透明树脂制成的物品，而这在以前是无法实现的。

EPFL的3D打印机是世界上速度最快的打印机之一。大多数3D打印机是通过一层一层地沉积材料来工作的，这一过程被称为增材制造。而EPFL使用的是容积法，即将树脂倒入容器中并旋转。工程师从不同的角度用光照射容器，使树脂中积累的能量超过给定水平时就会固化。这是一种非常精确的方法，可以与现有3D打印技术相同的分辨率制造物品。

这一容积法可用于几乎任何形状的物体。工程师们只花了20秒就制作出《星球大战》中的尤达（Yoda）的微小雕像，而传统的制造工艺大约需要10分钟。

光线能够通过与塑料中包含的光敏化合物相互作用来固化树脂。工程师表示，新方法只有在光线以直线穿过树脂而没有偏离的情况下才有效，而不透明树脂中光无法顺利传播。为此，他们设计出一种解决方案。

首先，他们使用摄像机观察光线通过树脂的轨迹，然后通过调整计算来补偿光线失真。他们还对打印机进行了编程，以便运行计算并校正光线，这确保了机器能适时达到固化树脂所需的能量。于是，工程师们能够以几乎与透明树脂相同的精度打印不透明树脂中的物体，这是一个重大突破。

下一步，工程师们希望能够同时利用新方法打印几种材料，并将打印机的分辨率从十分之一毫米提高到微米。（实习记者张佳欣）

As early as 2017, engineers at the Applied Photonic Devices Laboratory (LAPD) of the EPFL School of Engineering designed a 3D printer that could make objects almost instantly. Five years later, the team improved their printing equipment and methods to produce objects made of opaque resin, which could not have been achieved before.

EPFL's 3D printer is one of the fastest in the world. Most 3D printers work by depositing materials layer by layer, a process known as adding material. EPFL uses the volumetric method, which pours the resin into the container and rotates it. Engineers illuminate the container from different angles so that when the energy accumulated in the resin exceeds a given level, it will solidify. This is a very accurate way to make objects at the same resolution as the existing 3D printing technology.

This volume method can be applied to almost any shape of object. It took engineers only 20 seconds to make a tiny statue of Yoda in Star Wars, while the traditional manufacturing process took about 10 minutes.

Light can solidify the resin by interacting with photosensitive compounds contained in the plastic. Engineers say the new method works only if the light passes through the resin in a straight line without deviating, while the light in the opaque resin does not travel smoothly. To this end, they designed a solution.

First, they use a camera to observe the path of light through the resin, and then adjust the calculation to compensate for the light distortion. They also programmed the printer to run the calculations and correct the light, which ensured that the machine reached the energy needed to solidify the resin in time. As a result, engineers were able to print objects in opaque resin with almost the same precision as transparent resin, which was a major breakthrough.

Next, engineers hope to be able to use the new method to print several materials at the same time and increase the printer's resolution from 1/10 mm to micron. (trainee reporter Zhang Jiaxin)