3D printing technology has penetrated more and more deeply into human life.
The principle of 3D printing is actually the same as that of ordinary printers that we are familiar with. Ordinary printers can print the text and charts in the computer on a piece of white paper. When you zoom in on these text charts, you can see that they are composed of tiny colored ink dots. We call these dots. pixel. If these pixels are “printed” on the top, bottom, left and right and front and rear surfaces at the same time with three nozzles, what will be the effect? 3D printing is the culmination of this idea.
The finished product that needs to be printed is also designed in the computer and then sent to the 3D printer. The printer decomposes the object into thin layers as thin as paper, and then sprays the corresponding “pixels” on each layer. Finally, these planes are stacked together to form the object in the computer blueprint.
Of course, the composition of these “pixels” is no longer ink, but the corresponding raw materials are selected according to the real objects. The earliest raw material is plastic, and people can print all kinds of plastic products. Later, the types of raw materials became more and more diverse, and the emergence of various materials such as gypsum, nylon, resin, metal and ceramics made 3D printing more worthy of its name.
However, 3D printing still has two difficult problems to solve so far: it is not precise and time-consuming. Since the printed 3D objects are stacked layer by layer, seams or even deviations are inevitable when stacked, so it is difficult to be as perfect as a machine-made one-piece appliance. Moreover, just as color printing takes longer than black and white printing, the more “pixels” that need to be ejected, the longer it takes. Even if it is to print a small ornament, 3D printing will take several hours. Not to mention other more complicated stuff. How to solve these two big problems?
Using quantum dots as the ink for 3D printing, the smallest material humans can control so far, may solve the first big problem. Scientists at the Massachusetts Institute of Technology have used fluorescent particles to print objects about 1 cubic millimeter in size with a resolution of 50 nanometers. If researchers want to make larger objects about 1 cubic centimeter, the resolution drops accordingly to about 500 nanometers. But compared to other 3D-printed objects, the 500-nanometer-resolution object is already very fine—its imperfections can only be seen under a high-performance optical microscope.
The traditional 3D printing technology is like stacking wood, stacking raw materials into a whole layer by layer, which is inefficient and time-consuming. If we can use a complete raw material to form a finished product like mechanized production, wouldn’t it be possible to greatly improve efficiency and shorten time? Several materials scientists at the University of California, Berkeley, came up with this new 3D printing technique: place the raw material in a container and use a beam of light as a “knife” to “carve” the finished product out of solution.
The researchers chose a photosensitive liquid (methacrylate gelatin hydrogel) that selectively solidifies according to the intensity and direction of the light. When the light is projected from different angles, this multi-angle exposure superposition can Let the photosensitive liquid cure to the design.
Once the design is complete, the researchers project the blueprint with an ordinary projector, with a beam of light passing through the image onto a continuously rotating container of light-sensitive liquid. Slowly, the real object was “carved” out of the solution.
Putting on different blueprints, researchers can produce many objects, such as toy airplanes, crystal cage balls and even denture models, etc., and depending on the precision and material conditions, the printing time is only 30 to 120 seconds. The highest precision of this system can currently reach 0.3 mm, which is a potential 3D printing technology that can take into account both time and precision. In the future, as the variety of photosensitive materials increases, more and more items can be printed.
In the further future, this method could also be used to make nanoscale electronics or robots.
