A research team from Aalto University in Finland recently demonstrated a new passive technology for future 6G, which is expected to significantly improve the indoor and outdoor "signal dead spots" problem without adding base stations and electrical equipment. Researchers created a three-dimensional structural panel called "metacrystal" through 3D printing. The geometric structure itself can redirect and regulate radio waves, guiding signals that were originally blocked or seriously attenuated to the area where users and devices are located.
In complex environments such as underground offices, warehouse shelves, tunnels or large indoor venues, uneven wireless signal coverage has always been a persistent problem. As 6G networks shift to higher frequency bands in the future to carry greater data capacity, the signal's ability to penetrate walls, furniture and even people will further decrease, and this problem is expected to become more prominent. The Aalto University team believes that instead of adding more antennas, repeaters or active network equipment, it is better to use "passive structures" that do not require power supply to reshape the electromagnetic environment at the physical level.
According to reports, this 3D printed "super crystal" panel can be installed on walls, ceilings, furniture surfaces, etc., and is responsible for routing wireless signals around obstacles, guiding them to areas with weak coverage, or focusing them on specific users and terminal devices. Unlike many "smart surfaces" that only work in a single direction or in a single functional mode, these panels can process multiple incoming electromagnetic waves simultaneously and work together on multiple frequency bands to support reflection, transmission, and even absorption of unwanted interfering signals.
The research team pointed out that compared with traditional reconfigurable smart surfaces that rely on a large number of adjustable components and complex control systems, this passive "supercrystal" has obvious advantages in cost and deployment complexity. The panels can be produced through conventional 3D printing processes, and the material cost is expected to be only tens of euros per panel. The geometric structure can be customized for specific scenes instead of using a uniform template, so as to better fit the actual environment layout.
Mahdi Asgari, the PhD researcher who led the project, likened the concept to "guiding light with a mirror." He said that if the room is too dark, you can choose to add lamps or place mirrors to guide the existing light; the "supercrystal" panel plays a similar role as a "mirror" in wireless communications, except that the object becomes radio waves. Different from previously proposed single-layer smart surface solutions, this three-dimensional volume structure can independently control multiple incident signals or different frequency bands within the same panel. It is regarded as a key step towards real communication scenario applications.
From the perspective of application prospects, the research team believes that environments such as factories, warehouse centers, indoor 5G/6G private networks, and long corridors will be the most attractive implementation scenarios for this type of passive panels. In these spaces, the layout is relatively stable or changes slowly. As long as the space structure and equipment location are fully understood during the design stage, panels that match the environment can be customized in advance without the need for subsequent active adjustments and operation and maintenance. Asgari believes that for such scenarios, passive panels optimized for a specific layout are often cheaper, simpler, and easier to deploy at scale than active smart surfaces that require constant control and maintenance.
Currently, this technology is still in the transition stage from the laboratory to real-life applications. The research team has begun seeking potential industrial partners, including companies interested in programmable metasurfaces, smart wireless infrastructure, and low-cost passive signal control systems. The team hopes to see large-scale scalable "intelligent wireless environments" put into practical use in indoor spaces and outdoor urban environments in the future, so that wireless coverage in complex spaces can be as finely designed as lighting.
In the next step, the scientific research team plans to move from fixed design to reconfigurable design and develop panels that can adaptively adjust as the wireless environment changes. They pointed out that many reconfigurable smart surfaces are currently difficult to popularize in industrial scenarios. An important reason is high cost, complex structure, and high control system maintenance costs. Therefore, the team is working hard to explore a more simplified adjustable structure and manufacturing process, hoping to maintain reconfigurability while still maintaining low enough costs and deployment thresholds to meet the broad application needs of the future 6G era.
This research was published under the title "Metacrystals: inversely-designed 3D-printed intelligent panels for 6G communications". The paper was launched on June 8, 2026, and provided detailed technical details of related electromagnetic design and performance verification.