In situ laser-induced (ISLI) direct 3D printing of free-standing thermoset devices. Left: By integrating a 1,064-nm laser focused on the polymer ink jet for in situ curing, 3D structures can be constructed without supporting materials. Right: The laser-induced photothermal effect dramatically increases the Young's modulus (top) and tunes crosslink density (middle), enabling a fast liquid-solid transition, programmable mechanical and electrical properties, and complex unsupported structures (bottom). Credit: Reposted with permission from Qibin Zhuang et al., Nature Electronics, 2025.
Thermosets, such as epoxy and silicon rubbers, are a class of polymer (i.e., plastic) materials that harden permanently when they undergo a specific chemical reaction, known as "crosslinking." These materials are highly durable, heat-resistant with excellent electrical insulation in various applications such as in adhesives, coatings, and automotive parts.
Thermosets are also widely used to fabricate electronic components, including switches, circuit breakers and other core circuit components.
So far, thermoset-based free-standing devices have proved difficult to construct by using conventional 3D printing processes. One key reason for this is that the materials need to be provisionally supported by other supporting objects until they become solid, which adds more steps to the printing process.
Researchers at Xiamen University, University of California, Berkeley and other institutes have introduced a new approach to reliably print 3D free-standing thermoset devices without any supplementary structures. This method, presented in a paper published in Nature Electronics, combines a 3D printing method known as direct ink writing with a laser-assisted solidification process.
"Thermoset materials (such as silicones) are widely used in engineering and infrastructure applications," Dezhi Wu, co-senior author of the paper, told Tech Xplore.
"However, their 3D printing processes suffer from prolonged curing time and complicate supporting structures to make freestanding structures as they will sag and collapse before solidification. The laser manufacturing tools in our lab are utilized to directly print thermoset ink materials to cure the ink instantly."
Combining 3D printing with laser-induced solidification
The 3D printing approach introduced by the researchers has several advantages. Firstly, it drastically reduces the time required to produce thermoset structures from hours to seconds. Secondly, the new method also enables the direct printing of free-standing 3D thermoset structures without the need for support materials. Finally, it enables the in-situ engineering of specific mechanical and electrical properties during the printing process, which is highly advantageous when fabricating systems for specific applications.
Optical pictures of free-standing 3D structures with diverse thermosets. Materials (left to right, top to bottom): PDMS; PDMS with red pigment; PDMS with black pigment; Dragon Skin with orange pigment; Ecoflex with blue pigment; and PDMS with white, yellow, and red pigments. Credit: Reposted with permission, Qibin Zhuang et al., Nature Electronics, 2025.
"Free-standing thermoset devices offer two unique advantages," said Liwei Lin, co-senior author of the paper.
"First, the in-situ laser curing process eliminates the scheme used in conventional 3D processes by the supporting materials and post-process to remove the supporting structures.
"This enables the efficient fabrication of complex 3D geometries and broader device functionality. Second, the properties of printed 3D structures are programmable. For example, the local mechanical stiffness and electrical conductivity can be adjusted by the printing parameters so that different regions can be made softer or stiffer, and their conductivity can be high or low."
The careful engineering of specific properties in specific parts of a structure could be particularly valuable when developing systems that can benefit from being stiffer or softer in different places. For example, it could be useful to develop comfortable wearable devices or functional robots with flexible joints that can conduct electricity in some parts of their body and not in others.
"To tailor the structures' properties, we focus a 1,064-nm laser on the polymer jet near the nozzle tip, where the in-situ localized gelation of the thermoset ink is induced based on the photothermal effect," explains Lin.
Opening new paths for the manufacturing of thermoset devices
To demonstrate the potential of their 3D printing method, the researchers used it to print various thermoset-based free-standing devices, including stretchable electronic components, soft sensors and 3D magnetic robots. Their proposed approach achieves a fine printing resolution (i.e., down to 50 µm) and can be easily adapted for the fabrication of a wide range of devices.
"This approach produces high-resolution, free-standing architectures from diverse thermoset inks without additional support materials or prolonged post-processing," explained Wu.
"By adjusting laser power and printing parameters, we control Young's modulus along the filament, enabling stiffness gradient and spatially programmable functionality. Our method thus enables the volumetric programming of properties, such as mechanical stiffness and electrical conductivity."
ISLI printed butterfly soft robot placed on the petal of a Phoenix flower to highlight its intricate, unsupported 3D structure and light weight. Credit: Xiamen University Qibin Zhuang, Dezhi Wu & UC Berkeley Liwei Lin.
In the future, the 3D printing strategy employed by Lin, Wu and their colleagues could enable the manufacturing of new and diverse flexible electronic devices on a large scale. In addition to the fabrication of soft robots, it could support the scalable production of organ-on-chip systems and bio-compatible devices with advanced functionalities and complex 3D geometries.
"We now plan to build a robust 3D-printing platform for the construction of soft, multi-functional devices," added Wu. "We will also expand the printable ink toolbox and investigate the optimal printing parameters toward industrial applications, such as flexible electronics, organ chips and so on."
Written for you by our author Ingrid Fadelli, edited by Sadie Harley, and fact-checked and reviewed by Robert Egan—this article is the result of careful human work. We rely on readers like you to keep independent science journalism alive. If this reporting matters to you, please consider a donation (especially monthly). You'll get an ad-free account as a thank-you.
More information: Qibin Zhuang et al, Laser-assisted direct three-dimensional printing of free-standing thermoset devices, Nature Electronics (2025). DOI: 10.1038/s41928-025-01491-2.
