New technology uses light to engrave erasable 3D images
Study: Chemical "switch" and projector make any polymer a reusable 3D canvas
image:
A two-dimensional light engraving (left) suspended in a polymer film. The original photo (right) was projected into the film using a red- and blue-light projector that activates a photosensitive additive in the polymer. Applying heat to the film will erase the image and make it ready to use again.
view moreCredit: Ivan Aprahamian/Sara Patch
Imagine if physicians could capture three-dimensional projections of medical scans, suspending them inside an acrylic cube to create a hand-held reproduction of a patient's heart, brain, kidneys, or other organs. Then, when the visit is done, a quick blast of heat erases the projection and the cube is ready for the next scan.
A new report in the journal Chem by researchers at Dartmouth and Southern Methodist University (SMU) outlines a technical breakthrough that could enable such scenarios, and others with widespread utility.
The study introduces a technique that uses a specialized light projector to imprint two-dimensional and 3D images inside any polymer that contains a photosensitive chemical additive the team developed. The light-based engraving remains in the polymer until heat is applied, which erases the image and makes it ready to use again.
In short, the researchers write with light and erase with heat or light, says Ivan Aprahamian, professor and chair of chemistry at Dartmouth and co-corresponding author on the paper. In test trials, the researchers produced high-resolution images in polymers ranging from thin films to six inches thick.
The technology is intended for any situation where having detailed, precise visual data in a compact and easily customizable format could be critical, Aprahamian says, such as planning surgeries and developing architectural designs. The device also could be used for generating 3D images for education and even creating art, he says.
"This is like 3D printing that is reversible," Aprahamian says. "You can take any polymer that has the optimal optic properties—that is, it's translucent—and enhance it with our chemical switch. Now that polymer is a 3D display. You do not need virtual reality headsets or complicated instrumentation. All you need is the right piece of plastic and our technology."
Readily available polymers—such as an acrylic cube—could be transformed into a display with the addition of the light-sensitive chemical "switch" formulated by Aprahamian and Qingkai Qi, a postdoctoral researcher at Dartmouth and the study's first author. The switch consists of a compound called azobenzene that reacts to light paired with boron difluoride, which enhances the switch's optical properties.
Once integrated with a polymer, the switch reacts to wavelengths of red and blue light beamed from a projector developed in the lab of Alex Lippert, professor of chemistry at SMU and co-corresponding author of the study. Study co-author Joshua Plank is a PhD candidate in Lippert's lab. The red light acts like ink by activating the chemical additive to create the image, Aprahamian says. Blue light can then be used to erase it.
The projector illuminates the treated polymer from different angles with various patterns of light, Lippert explains. The photosensitive chemical developed in Aprahamian's lab at Dartmouth is activated where these patterns intersect to produce 3D patterns. Creating 3D projections from 2D images such as a chest X-ray would mean projecting slices of the original image into a polymer cube or other shape until the slices combine to form the full 3D image, Lippert says.
The researchers have been able to produce animated images in polymers and future work revolves around improving that process. In the meantime, the technology reported in Chem could be developed for practical use in its current form, such as for industry or health care.
"Scaling up requires tuning the chemical switch properties to improve resolution, contrast, and refresh rate," Lippert says. "The projector system can in principle be scaled up and developed into a turnkey system with automated hardware and associated software for easy us
The reseachers are able to produce light-based three-dimensional and animated images in polymers ranging from thin films to six inches thick. They project slices of original two-dimensional images until the slices combine to form a full 3D or animated image. Future work revolves around improving the process for creating animated images.
Credit
Ivan Aprahamian
Journal
Chem
Method of Research
Experimental study
Subject of Research
Not applicable
Article Title
A Photoswitchable Hand-Held Volumetric 3D Display
Article Publication Date
9-Aug-2024
3D laser printing with bioinks from microalgae
Heidelberg researchers successfully develop a new generation of biocompatible materials for additive manufacturing
Microalgae such as the diatom Odontella aurita and the green alga Tetraselmis striata are especially suitable as “biofactories” for the production of sustainable materials for 3D laser printing due to their high content in lipids and photoactive pigments. An international research team led by Prof. Dr Eva Blasco, a scientist at the Institute for Molecular Systems Engineering and Advanced Materials (IMSEAM) of Heidelberg University, has succeeded for the first time in manufacturing inks for printing complex biocompatible 3D microstructures from the raw materials extracted from the microalgae. The microalgae-based materials could be used in future as the basis for implants or scaffolds for 3D cell cultures.
Among the additive manufacturing techniques, two-photon 3D laser printing offers particular advantages for manufacturing at the micro- and nanoscale. Owing to its remarkable resolution, it finds application in numerous fields including optics and photonics, microfluidics, and biomedicine. The process involves focusing a laser beam on a liquid, photoreactive resin, a so-called “ink”. At the focal point, the laser light activates special molecules known as photoinitiators and triggers a chemical reaction, causing local solidification of the ink.
To date, petrochemical-based polymers have been mainly used as inks for this highly precise 3D laser printing process. However, these polymers contribute to the depletion of fossil fuels and the emission of greenhouse gases and can also contain toxic components, as Prof. Blasco points out. Microalgae are particularly well suited as “biofactories” for the production of sustainable materials for 3D printing due to their rapid growth rate, CO2-fixation during cultivation, and biocompatibility. “Despite their advantages, microalgae have hardly been considered as raw materials for light-based 3D printing,” says Prof. Blasco, whose group conducts research at the interface of macromolecular chemistry, materials science, and 3D nanofabrication.
The research team succeeded for the first time in extracting biocompatible materials for high-resolution 3D laser printing from microalgae. For their experiments, the researchers selected two species – the diatom Odontella aurita and the green alga Tetraselmis striata – that contain particularly high levels of lipids in the form of triglycerides. The team extracted the triglycerides and functionalized them with acrylates to facilitate rapid curing under light irradiation. The photoactive green pigments present in the microalgae proved to be suitable as photoinitiators. When exposed to light, they trigger the chemical reaction that solidifies the ink into a three-dimensional structure. “In this way we avoid using potentially toxic additives like the photoinitiators used in conventional inks,” explains first author Clara Vazquez-Martel, a doctoral candidate in Eva Blasco’s research team at IMSEAM.
Using the new ink system, the researchers were able to produce different 3D microstructures with high precision, exhibiting complex features such as overhanging roofs and cavities. Using cell culture experiments, the researchers also investigated the biocompatibility of the microalgae-based inks. They prepared 3D microscaffolds on which the cells were cultured for about 24 hours. They observed a survival rate of almost 100 percent. “Our results open up new possibilities not only for more sustainable 3D printing with light, but also for life science applications – from 3D cell cultures to biocompatible implants,” says Prof. Blasco.
The research was conducted within the Cluster of Excellence “3D Matter Made to Order”, a collaboration of Heidelberg University and the Karlsruhe Institute of Technology (KIT). This study involved researchers from Heidelberg, the KIT, and the Spanish Bank of Algae at the University of Las Palmas de Gran Canaria (ULPGC, Spain). The work was funded by the German Research Foundation, the Carl Zeiss Foundation, the Fonds der Chemischen Industrie, and the European Union in the framework of the European Territorial Cooperation Program. The research has been published in the journal “Advanced Materials”.
Journal
Advanced Materials
Article Title
Microalgae-Based Materials for 3D Printing with Light. Advanced Materials
