Researchers at Aalto University have developed a class of passive signal-management devices — called metacrystals — that redirect radio waves around physical obstacles without requiring power, active tuning or control circuitry. 

The panels are fabricated using 3D printing from plastic and are designed to address one of the fundamental coverage problems expected to affect sixth-generation (6G) wireless networks: the tendency of high-frequency signals to be blocked by walls, people and other physical barriers.

Aalto University researchers use 3D printed panels to solve 6G coverage issues

Unlike conventional reconfigurable intelligent surfaces (RIS), which depend on tunable electronic elements and complex control circuits, metacrystal panels are single-piece plastic structures. The estimated cost of consumable material per panel runs to a few tens of euros, and the additive manufacturing process allows each unit to be configured for a specific environment rather than produced as a universal device.

“When a room is too dark, you can bring in more lamps – or use simple mirrors to guide the already available light. This is what these metacrystals do, but with radio waves,” explained doctoral researcher Mohammadmahdi Asgari, Aalto University.

“Unlike previously proposed single-layer intelligent surfaces, these volumetric metacrystals can be designed to control multiple incoming signals or frequency bands independently — a key requirement for realistic wireless communication.”

Factory floors and long corridors

The panels can be mounted on walls, ceilings or furniture and are capable of operating in both reflection and transmission modes, handling multiple incoming signals across different frequency bands simultaneously. They can also fully absorb unwanted signals. The research team identified static or slow-changing environments as the most commercially promising deployment context.

“For industry, the most attractive use cases are static or slowly changing environments like factories, indoor 5G/6G networks, warehouses, and long corridors,” said Asgari. “In such places, a passive panel designed for a known layout could be much cheaper and simpler than an actively controlled surface that additionally requires continuous maintenance.”

Asgari stated that complex electromagnetic functionality can now be realized as a low-cost, single-piece plastic structure ready to be put on a wall, with geometry alone doing the work once installed.

Path to commercialization

The Aalto team is currently exploring routes to commercialization and is seeking engagement from industrial partners working in programmable metasurfaces, wireless infrastructure and passive signal-control technologies. The next development phase involves moving from static panels toward reconfigurable versions capable of adapting as wireless environments change.

“The hope would be that in the future we can see these scalable, smart wireless environments put to practical application in indoor spaces and outdoor urban settings, on building walls or other architectural surfaces,” said Asgari.

The research findings were published in Nature Communications.