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Nanoscale 3d printer
From nano to macro: Nanoscale 3D printing that is fast, smooth, and scalable - Mechanical Engineering
3D-printed objects look impressive, but the printing process is slow, and removing their jagged edges and external support structures requires a lot of tedious post-processing work. The same is true at the nanoscale, where tiny objects are built to incredibly precise tolerances. A team of Purdue University researchers has demonstrated a 3D printing technique that rapidly constructs complex nanoscale 3D objects with smooth features, and can be implemented to build complex macroscale objects on a practical time scale.
Additive manufacturing – also called 3D printing – has revolutionized many fields, and has spurred researchers to investigate manufacturing techniques at the micro- and nano-scale. One such technique is multi-photon lithography, where a volume of resin is exposed to a series of focused high-intensity laser pulses, which causes the resin at the focal point to solidify almost instantly. By moving the laser and/or the resin, 3D shapes can be built.
In a new paper published in Light: Science & Applications, a Purdue team led by Xianfan Xu, the James J. and Carol L. Shuttleworth Professor of Mechanical Engineering, has combined multi-photon lithography with spatiotemporal focusing of femtosecond laser pulses to demonstrate rapid, continuous printing of complex 3D structures.
Paul Somers uses a digital micro-mirror device to direct ultrashort laser pulses onto a customized moving stage, enabling rapid nanoscale 3D printing.
“Multi-photon lithography has been studied for more than 20 years,” said Paul Somers, PhD student in Mechanical Engineering, and lead author of the paper. “It has great potential, but it’s still slow. Our goal is to speed it up and scale it up, so that it can be used to manufacture useful structures with high speed and high fidelity.”
To achieve this goal, they use spatiotemporal focusing.
A digital micro-mirror device (an array of tiny mirrors controlled by a computer) separates the laser into multiple wavelengths of light and then recombines them, which accurately pinpoints the area of the resin they want to solidify. With this technique, they can print an entire 2D layer instantly, while physically moving the platform up and printing another horizontal layer.
“You see this with typical 3D printers, where it deposits a layer of plastic, and then moves up to deposit another layer, leaving you with jagged edges,” Somers said. “But our technique is continuous. The platform doesn’t stop and start; it moves continuously, so rather than distinct layers, it’s one smooth shape all the way up. This allows us to print much faster, with no layering artifacts, and make complex shapes that traditional 3D printing can’t do.”
They demonstrated this technique by printing complex rounded shapes like a trefoil knot, and a replica of the Cloud Gate sculpture in Chicago – each printed in less than a second, with no jagged edges or other artifacts.
This nanoscale 3D printing technique enables the construction of complex curved shapes, like this replica of the Cloud Gate sculpture (left), and a trefoil knot (right). Both shapes are approximately 25 microns wide, about one third the width of a human hair.
Because of the size of their mirror array, the layer size was restricted to 25 microns by 44 microns. To counter this restriction, they combined multiple tiny structures into one larger structure. In one printing session, they printed more than 74,000 of the tiny shapes into a 42 x 42 x 42 unit cube, nearly 1 millimeter in width. This demonstrated that multi-photon lithography has the potential to build highly complex structures, with customized designs, in a practical time frame.
“Imagine a doctor wants to bio-engineer a custom scaffolding for tissue cells to grow on,” Somers said. “With this technique, we can rapidly build multiple nanostructures into a complex macroscale object. We can achieve the same detailed properties of the nanostructures, but build them into objects that are useful in the real world, in a practical timeframe.
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“To make nanomanufacturing practical, we have to optimize time and scale,” Xu said. “Creating a single nanostructure in a lab, over several days, just doesn’t scale. With this technique, we can make nanoscale 3D printing practical for biomedicine, microrobotics, optics, consumer products, and more.”
The team also includes Liang Pan, Associate Professor of Mechanical Engineering; and Bryan Boudouris, Professor of Chemical Engineering. All research takes place at the Birck Nanotechnology Center. This work was supported by the National Science Foundation through their Scalable Nanomanufacturing Program, award number 1634832.
Writer: Jared Pike, [email protected], 765-496-0374
Source: Xianfan Xu, [email protected], 765-494-5639
ABSTRACT
Rapid, Continuous Projection Multi-photon 3D Printing Enabled by Spatiotemporal Focusing of Femtosecond Pulses
Paul Somers, Zihao Liang, Jason E.
Johnson, Bryan W. Boudouris, Liang Pan, Xianfan Xu
There is demand for scaling up 3D printing throughput, especially for the multi-photon 3D printing process that provides sub-micrometer structuring capabilities required in diverse fields. In this work, high-speed projection multi-photon printing is combined with spatiotemporal focusing for fabrication of 3D structures in a rapid, layer-by-layer, and continuous manner. Spatiotemporal focusing confines printing to thin layers, thereby achieving print thicknesses on the micron and submicron scale. Through projection of dynamically varying patterns with no pause between patterns, a continuous fabrication process is established. A numerical model for computing spatiotemporal focusing and imaging is also presented which is verified by optical imaging and printing results. Complex 3D structures with smooth features are fabricated, with millimeter scale printing realized at a rate above 10-3 mm3 s-1.
This method is further scalable, indicating its potential to make fabrications of 3D structures with micro/nanoscale features in a practical time scale a reality.
Researchers enable nanoscale metal parts using new 3D printing technology
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Researchers from ETH Zurich and Nanyang Technological University (NTU) have developed a new 3D printing technique capable of producing nanoscale metal parts.
Based on an electrochemical approach, the process can be used to fabricate copper objects as small as 25 nanometers in diameter. For reference, an average human hair is around 3000x thicker at 75 microns.
According to the research team led by Dr Dmitry Momotenko, the new 3D printing technique has potential applications in microelectronics, sensor technology, and battery technology.
The new 3D nanoprinting technique works by depositing metal ions onto a negatively charged substrate to produce tiny metal objects. Image via ETH Zurich.Adapting electroplating for additive manufacturing
The ETH/NTU nanoprinting approach is actually based on the process of electroplating, a well-known metal coating technique used in the world of manufacturing.
To electroplate a part, manufacturers suspend positively charged metal ions in a salt solution. A negatively charged electrode is then added to this liquid solution, which causes the ions to combine with the electrons in the electrode and form neutral metal atoms. The atoms are deposited as a coating on the electrode and slowly form a solid layer on the surface.
Momotenko adds, “In this process, a solid metal is fabricated from a liquid salt solution – a process that we electrochemists can control very effectively.”
The nanoprinting process operates on the exact same premise, whereby a tiny pipette is used to deposit positively charged copper ions onto a negatively charged print surface. In this case, the team used a nozzle tip just 1.6 nanometers wide, meaning only two copper ions could pass through at a time. This, combined with several electrochemical printing parameters, allowed the team to closely control the diameter of the printed structures. The paper reports that the smallest of the printed objects came out at just 25 nanometers wide (195 copper atoms).
On the other hand, conventional powder-based metal 3D printers are typically only capable of reaching micron-level resolutions, which are still several thousand times larger than those in the present study.
“The technology we are working on combines both worlds – metal printing and nanoscale precision,” explains Momotenko.
The approach can be used to print vertically, horizontally, and at inclines. Image via ETH Zurich.Applications of metal 3D nanoprinting
Interestingly, Momotenko’s team found that their 3D printing process was able to fabricate a wide variety of object types, including vertical structures, horizontal structures, inclines, and even spirals. The powerful approach lends itself to a whole host of novel applications such as more efficient energy storage devices, microelectronics, and even 3D printed catalysts for chemical production purposes.
As far as future work goes, the researchers are currently working on applying the technique to 3D print more compact lithium-ion batteries.
The designs are set to feature increased surface areas on the electrodes and shorter distances between the electrodes, all in a bid to speed up the charging process.
Further details of the study can be found in the paper titled ‘Bringing Electrochemical Three-Dimensional Printing to the Nanoscale’.
SEM imaging of 3D printed copper nanostructures. Image via ETH Zurich.The research sphere is often home to some of the most innovative 3D printing techniques around. Back in October, researchers at Loughborough University developed a novel hybrid 3D printing technique that allows them to change the properties of printed parts over time, enabling a new form of 4D printing. Named Material Treatment Extrusion Additive Manufacturing (MaTrEx-AM), the approach combines conventional extrusion-based 3D printing with a chemical treatment.
Elsewhere, at Fraunhofer IWS, scientists revealed the testing of a 3D printing system that could be up to “a thousand times faster” than current mirror-based laser manufacturing technologies.
Built around a high-powered 13 KW ‘Dynamic Beam Laser,’ the institute’s setup is said to be capable of rapidly generating different energy distribution patterns, and precisely printing the most demanding of materials.
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Featured image shows the new 3D printing technology. Image via ETH Zurich.
Tags Dmitry Momotenko ETH Zurich nanyang technological university
Kubi Sertoglu
Kubi Sertoglu holds a degree in Mechanical Engineering, combining an affinity for writing with a technical background to deliver the latest news and reviews in additive manufacturing.
| 3DNews Technologies and IT market. News printers, print servers, scanners, copiers... German scientists figured out how to make 3... The most interesting in the reviews 12/01/2021 [12:43], Gennady Detinich Today, we are not surprised by compact laser printers, although in the early days of technology and for many years after the introduction of laser printers into the market, laser printers were surprising in size and weight. The situation is similar with laser 3D printing. These are high-precision additive modeling devices, but the dimensions of the devices remain relatively large - about the size of a voluminous suitcase or so. New German technology will help reduce such printers to the size of a shoebox. On the left is an image of a printed 3D structure under an electron microscope, on the right - under an optical one. Modern laser printing as part of a 3D printer is a complex optical system that, in a pulsed femtosecond pulse mode, causes the chemical polymerization of a material at a focal point. The large dimensions and prohibitive high cost of such printers do not allow them to become a product for widespread use. Can this be changed? Quite, said researchers from the German profile cluster 3D Matter Made to Order. Scientists in the journal Nature Photonics published an article in which they talked about the innovative design of a laser printer head for 3D printing with nanoscale precision. In a conventional laser 3D printer, the polymerization of a light-sensitive liquid occurs when two photons simultaneously excite a molecule of the liquid - this is the so-called two-photon absorption. In order for the two-photon (simultaneous) absorption reaction to occur, the laser system must be complex, matched, and therefore unwieldy. German scientists proposed to divide the excitation of light-sensitive liquid molecules into two stages and perform them in turn, which would radically reduce the laser head and the design of the 3D printer. In particular, researchers at the Karlsruhe Institute of Technology (KIT) and the University of Heidelberg have proposed a two-stage absorption that works with inexpensive and small blue laser diodes. The first photon transfers the molecule to an intermediate state. At the second stage, the second photon transfers the molecule from the intermediate state to the desired excited state and starts the chemical reaction. Absorption of two photons does not have to occur simultaneously, which was the key to the breakthrough. “Compact and low-power CW laser diodes, , can be used for this process,” said Vincent Hann, first author of the study at KIT's Institute of Applied Physics (APH). - Required laser power is much lower than conventional laser pointers. However, not everything is so simple. The breakthrough would not have been possible without the development of a new composition of photosensitive fluid. The new composition of the liquid was developed for several years together with chemists, until the desired result was obtained. “In my opinion, in the coming years it is realistic to create a device the size of a shoe box. It will be even smaller than the laser printer on my desktop at KIT, - said another author of the work, Professor Martin Wegener. - In this way, laser 3D nanoprinters can become affordable for many populations. Experts are already talking about the democratization of laser 3D printing technology.” Source: If you notice an error, select it with the mouse and press CTRL+ENTER. Related materials Permanent URL: News Hardware, nanotechnology, printers, print servers, scanners, copiers, MFPs, on the cutting edge of science, 3D technologies, Tags: 3d printing, nanotechnology, scientists ← В past To the future → |
Image Source: Professor Rasmus Schröder, University of Heidelberg, Vincent Hahn, KIT 
Nano-precision 3D printing
The highest resolution 3D printer breaks speed records at the Technical University of Vienna.
Printing 3D objects in incredible detail is made possible by "two-photon lithography" technology. It allows you to create the smallest objects of the nanometer scale. Researchers at the Technical University of Vienna (VTU) have made a major breakthrough by increasing the speed of this technology. Their high-precision 3D printer is several orders of magnitude faster than other similar devices (watch the video). This opens up completely new areas of application, such as medicine.
This video shows the 3D printing process in real time. Thanks to the very fast movements of the laser beam, 100 layers of about 200 lines each are printed in four minutes.
New world record
The 3D printer uses a liquid resin that is hardened in the right places by a high-precision laser beam. The focusing point of the laser is shifted using several mirrors, leaving behind a strip of hardened polymer only a few hundred nanometers wide.
This high resolution makes it possible to produce complex objects the size of a grain of sand. “Previously, this production method was quite slow,” says Prof. Jürgen Stampfl from the WTU Institute for Materials Science and Technology. “Print speed was measured in millimeters per second. The speed of our device is five meters per second.” This is a world record for two-photon lithography.
This amazing progress was made possible by the combination of several new ideas. “Improvements to the mirror control mechanism played a major role,” says VTU's Jan Torgersen. The mirrors are constantly in motion, and fine tuning of their acceleration and deceleration periods has helped to achieve highly accurate results at record speeds.
Photoactive molecules
In 3D printing, not only mechanics are important - chemistry also plays an important role. “The resin contains molecules that are activated by laser radiation. They cause a chain reaction in other components, the so-called monomers, which causes them to harden,” says Jan Torgersen.
These initiator molecules are activated only when two laser photons are absorbed, which becomes possible only in the very middle of the beam, where the radiation intensity is higher. Unlike conventional 3D printing methods, solid matter can be created anywhere, not just on top of the next layer. Thus, before creating a layer, it is not necessary to prepare the work surface in advance, which saves a lot of time. A team of chemists led by Prof. Robert Liska developed the right initiators specifically for the type of resin needed.
Researchers around the world are working on 3D printing technologies, both in universities and in industry. “At WTU, our advantage is that we have experts in many different areas and can approach a problem from different angles,” emphasizes Jürgen Stumpfl. Materials science, engineering, light source optimization - all experts work together and inspire each other to new ideas.
Thanks to this increase in speed, it is now possible to create objects of a larger scale in the same period of time.
