3D printing has already transformed the way engineers, researchers and manufacturers create complex objects. But a new approach called Tomographic Volumetric Additive Manufacturing (TVAM) could take this technology much further.
Researchers led by Tisato and colleagues have demonstrated a method that combines volumetric 3D printing with embedded 3D printing to create multi-material structures and extremely small internal channels in a single printing process. The technique could open new possibilities for microfluidics, advanced manufacturing, robotics, medical devices and other technologies that require complex structures made from different materials.
Moving Beyond Layer-by-Layer 3D Printing
Most familiar 3D printers create objects layer by layer.
In material-extrusion technologies such as Fused Deposition Modeling (FDM), a printer moves a nozzle along a programmed path and deposits material one line at a time. Direct Ink Writing (DIW) follows a similar principle but can print specialized inks, pastes and other materials.
These methods are relatively flexible and can combine different materials by changing the printing material or using multiple print heads. However, printing complex objects can take a long time. Support structures may also be necessary, producing additional material waste and requiring post-processing.
Another major technology is vat photopolymerization, including stereolithography (SLA) and masked stereolithography (MSLA). Instead of depositing material through a nozzle, these systems use light to cure a liquid resin.
They can provide excellent resolution and can be faster than extrusion-based printing. However, producing objects from multiple different materials remains difficult because different resins can mix inside the same vat.
A Different Way to Print in Three Dimensions
Tomographic volumetric additive manufacturing offers a fundamentally different approach.
Instead of constructing an object by repeatedly stacking thin layers, TVAM uses multiple 2D light projections to create a complete 3D light-dose pattern inside a rotating container filled with photosensitive resin.
When the projections are correctly calculated, the resin polymerizes in the desired three-dimensional shape.
This means a large part of the object can effectively be formed at once, rather than being built point by point or layer by layer.
The result can be dramatically faster printing, while also allowing the production of complex geometries without conventional support structures.
However, TVAM has its own limitations. The printing resin generally needs to be transparent to the light used during the process. The materials also need suitable optical and chemical properties for successful volumetric curing.
Researchers have demonstrated TVAM with several materials, including acrylates, hydrogels, ceramics and glass. Yet one major challenge has remained: how can different materials be placed in different parts of the same object without relying on complicated vat changes or simply embedding a previously made object?
Combining Two Printing Technologies
The researchers addressed this problem by combining TVAM with Embedded 3D Printing (EMB3D).
In embedded printing, a needle moves through a special supporting material and deposits an ink inside it. The support bath has carefully controlled properties. It must allow the printing needle to move through it while preventing the deposited ink from spreading or losing its shape.
This makes it possible to place material in precise three-dimensional patterns before the final structure is cured.
The researchers developed a process known as Embedded Extrusion-Volumetric Printing (EmVP).
The basic idea is simple but powerful.
First, an ink is deposited into a specially designed photopolymerizable support bath using embedded 3D printing. The deposited material can be positioned wherever it is needed.
Then, instead of printing the entire structure layer by layer, the researchers use TVAM to rapidly cure the structure volumetrically.
In other words, one technology is used to position different materials, while the other is used to rapidly create the final three-dimensional structure.
Creating Multi-Material Objects
One of the most important achievements of the research is the ability to create structures containing regions with different material properties.
When the embedded ink is also photopolymerizable and its curing behavior is compatible with the support material, both materials can be cured during the volumetric printing process.
This creates a multi-material object in which different areas can have different mechanical characteristics.
For example, one region can be designed to be relatively stiff while another can be more flexible.
Importantly, the materials do not have to be arranged only in simple horizontal layers. They can be positioned in different locations throughout the three-dimensional structure.
This gives designers much greater freedom when creating complex components.
Printing Invisible Paths Inside Solid Structures
The researchers also demonstrated another version of the process called negative EmVP.
Instead of using a photopolymerizable ink that becomes part of the final object, a non-photopolymerizable or sacrificial ink can be deposited inside the support material.
During volumetric curing, the surrounding material becomes solid while the sacrificial ink can later be removed.
The result is an internal channel inside the printed object.
This approach is particularly interesting for microfluidics, where tiny channels are used to control and transport fluids.
The researchers demonstrated microchannels with diameters of less than 120 micrometers.
To put that into perspective, a human hair is often around 50–100 micrometers wide. This shows how remarkably small these internal structures can be.
Why This Matters
Creating tiny internal channels using conventional 3D printing can be difficult. Traditional printers may struggle to produce such structures because of their layer-by-layer construction, limited resolution or complicated support requirements.
TVAM already provides an attractive route for creating complex three-dimensional shapes. By combining it with embedded printing, researchers can now add another level of control.
The approach also avoids some of the complicated solutions previously explored for multi-material volumetric printing.
Earlier methods could involve exchanging resins, carefully aligning multiple printing stages, embedding prefabricated structures or using different wavelengths of light to cure different materials.
EmVP can achieve multi-material structures without requiring a complex multi-wavelength projection system.
Potential Applications
The technology could eventually become useful across several fields.
Microfluidics is one obvious application. Researchers could manufacture devices containing extremely small channels for transporting fluids, chemical reactions, biological analysis and lab-on-a-chip systems.
The method could also benefit medical devices, where different regions may need different mechanical properties.
In soft robotics, components could potentially combine rigid and flexible regions within a single structure.
It may also be useful for advanced optical systems, sensors, customized mechanical components and other devices where conventional manufacturing struggles to create complicated internal geometries.
Challenges Still Remain
Despite its potential, the technology is still at the research stage.
TVAM requires carefully controlled optical conditions, suitable transparent materials and accurate projection calculations. The supporting bath and embedded inks also need carefully designed properties.
Scaling the technology to large industrial parts, increasing the number of compatible materials and maintaining consistent quality will require further research.
Manufacturers will also need to consider material durability, long-term stability, production costs and integration with existing industrial workflows.
So, while the technology is promising, it is not yet a replacement for conventional 3D printing.
A New Direction for 3D Manufacturing
The work by Tisato and the research team demonstrates an important shift in how volumetric 3D printing can be used.
Instead of choosing between speed and multi-material capability, EmVP attempts to combine both.
The approach uses embedded printing to precisely place different materials and TVAM to rapidly transform the overall design into a solid three-dimensional structure.
At the same time, the negative version of the process can create tiny internal channels that would otherwise be difficult to manufacture.
The significance of this research goes beyond simply making a faster 3D printer. It demonstrates a new manufacturing strategy in which different materials, complex shapes and microscopic internal structures can be integrated into a single printing workflow.
As researchers continue improving the materials, precision and scalability of volumetric printing, technologies such as EmVP could help move 3D printing from today's layer-by-layer manufacturing toward a future where entire complex structures are created in three dimensions, with materials placed exactly where they are needed.
Reference: Tisato, S., Vera, G., Song, Q. et al. Additive manufacturing of multi-material and hollow structures by Embedded Extrusion-Volumetric Printing. Nat Commun 16, 6730 (2025). https://doi.org/10.1038/s41467-025-62057-6
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