Multimaterial 2PP printing: the LLNL patent eliminates vat change with two wavelengths
Lawrence Livermore National Laboratory has filed a patent for a Two-Photon Polymerization printing system that makes it possible to vary the material's properties without interrupting the process. The technology uses two lasers with different wavelengths to selectively activate different chemistries in the same resin.
- Two coaxial lasers (1045 nm and tunable) focused at the same point
- A resin with two chemical systems: acrylic and epoxy
- Optical, not mechanical, material selection
- Variable properties: density, porosity, elastic modulus, refractive index
How the dual-wavelength system works
The patent describes a radically different approach to multimaterial printing: selection occurs by modifying the light, not by changing resin.
Patent application US20260249547A1, published on August 27, 2026, describes a system in which two laser beams are aligned coaxially and focused at practically the same point. The first beam operates at 1045 nm with a fixed wavelength. The second is tunable.
The resin simultaneously contains an acrylic system and an epoxy system. These are not two separate materials, but a single mixture in which both chemistries coexist in the same vat.
Selectivity derives from the differentiated photochemical response. At 1045 nm, essentially only the acrylic chemistry is activated. Around 700 nm, both the acrylic and the epoxy systems are activated.
Multi-materiality through photochemistry, not substitution
This is not multi-material printing in the traditional sense: it is local control of properties through selective photochemistry.
After printing, unreacted epoxy can be removed during post-processing. The region exposed at 700 nm remains fuller and denser. The one produced only at 1045 nm retains greater porosity.
The result is a microscopic structure with locally variable properties: density, porosity, elastic modulus, refractive index, or wettability can be modified without interrupting printing.
“Multi-materiality” here does not mean alternating two separate resins as with FFF dual extrusion. It is a form of property control through photochemistry selectivity, not through physical material change.
The inventors and the patent context
The application was filed by Lawrence Livermore National Security LLC, the company that manages LLNL for the Department of Energy.
The listed inventors are Magi Mettry Yassa, James Spencer Oakdale, Yoonsoo Rho, and Xiaoxing Xia. The application was filed on February 27, 2025, with number US19/065702.
Lawrence Livermore National Laboratory has been working for years on 2PP printing and high-resolution additive manufacturing technologies. This patent represents a significant evolution toward printing complex microstructures without process interruptions.
Implications for additive manufacturing
Eliminating the vat change could accelerate the production of micrometric components with graded properties.
Two-Photon Polymerization is a sub-micrometer-resolution 3D printing technology. Until now, producing structures with variable properties required replacing the resin, washing the component, or moving it between different vats.
The LLNL approach turns this mechanical limitation into an optical choice. By changing the wavelength, one decides which reactions to activate in the same volume of resin.
This could open up applications in microfluidics, integrated optics, biomedical scaffolds, and components with functional gradients controlled at the micrometer scale.
| Wavelength | Activated system | Result |
|---|---|---|
| 1045 nm | Acrylic only | Porous structure |
| ~700 nm | Acrylic + epoxy | Dense structure |
The patent is still under examination. If granted, it could represent a point of reference for the development of next-generation multimaterial 2PP systems.
article written with the help of artificial intelligence systems
Q&A
How does the LLNL patent's multimaterial 2PP printing system work?
The system uses two coaxial lasers focused on the same point to selectively activate different chemistries within the same resin. A 1045 nm laser activates only the acrylic component, while a tunable laser around 700 nm activates both acrylic and epoxy.
What materials does the resin used in the LLNL process contain?
The resin is a unique mixture simultaneously containing an acrylic chemical system and an epoxy one. It is not two separate materials, but a single solution where both chemistries coexist in the same vat.
Which material properties can be modified with this technology?
It is possible to locally vary density, porosity, elastic modulus, refractive index, and wettability without interrupting the printing process. Optical selection allows creating denser or more porous regions by controlling the wavelength.
How does this multimaterial printing differ from traditional methods?
Unlike traditional systems that physically change the resin or use dual extruders, here selection occurs by modifying the light rather than the material. This eliminates the need to stop printing to change the vat or nozzle.
Who are the inventors of patent US20260249547A1 filed by LLNL?
The inventors listed in the patent are Magi Mettry Yassa, James Spencer Oakdale, Yoonsoo Rho, and Xiaoxing Xia. The application was filed by Lawrence Livermore National Security LLC on behalf of the Department of Energy.
