In the near future, communication devices could be as portable and flexible as clothing.
Newly created blanket with radio-frequency antennas. Photo: Columbia Engineering team.
Experts have been exploring ways to integrate radio frequency properties into knitted textiles to create portable, deployable antennas. This advancement could particularly prove beneficial for those in remote or inaccessible locations.
The Columbia University engineers have achieved a major milestone. Using traditional flat-knitting techniques, they have created a first-of-its-kind 'blanket' embedded with metasurfaces.
These knitted antennas may benefit long-distance communication, offering a lightweight, flexible, and easy-to-deploy solution.
“We can leverage the very old and very well-established knitting industry to fulfil some of the needs of modern telecommunications. The facile and scalable nature of the fabrication approach means these devices could be inexpensive, ultra-lightweight, flexible variants of sophisticated radio-frequency communications antennas,” said Nanfang Yu who led the research.
A test swatch showing a wide variety of antenna archetypes, all knit using the float-jacquard knitting technique. Photo: Columbia Engineering team.
Float-jacquard knitting technique
In this new study, the team sought a cost-effective and efficient method to directly embed flat array antennas into textiles.
For this development, an old-school colourwork knitting technique called float-jacquard knitting was used.
This helped them create flexible, lightweight centimetre-wave metasurfaces, which are slim optical components that manipulate light.
The researchers utilized commercially available metallic and dielectric yarns to create their prototype fabric-based devices.
These specialised yarns, which conduct electricity or insulate, respectively, were processed using standard knitting machinery. The resulting prototypes included a metasurface lens and a vortex-beam generator, both of which are types of reflectarray devices.
To achieve the intricate patterns required for these devices, the researchers used float-jacquard knitting. In this method, multiple types of yarn are used to create a design.
“The group is the first to adapt flat-knitting techniques to incorporate antennas directly during the fabric production procedure – integrated fabrication – and able to do it at low cost and high yield on an industrial scale,” the authors noted in the press release.
Remarkably, each square-meter metasurface was knitted in just 45 minutes. Moreover, the flat-knit fabric devices proved incredibly resilient, surviving multiple wash cycles and stretching tests.
Interestingly, these metasurfaces function as large, portable antennas for long-distance communication.
The researchers experimentally demonstrated the metasurfaces’ dual functionality: first, as a receiving antenna, and then as a transmitting antenna.
Up next, they plan to expand their research by exploring various knitting techniques and machines to create even more complex and multifunctional fabrics. These fabrics could incorporate electronic circuits and other mechanical elements.
The scalability of flat-knitting techniques is a significant advantage. The researchers aim to leverage this capability to develop high-gain antennas with large apertures. These could be suitable for satellite communications over long distances.
“It’s important to stress that these devices were fabricated using commercially available off-the-shelf yarns and leveraging established fabrication techniques,” Yu said.
“I am almost certain that communities of knitters can come up with ingenious ways to integrate aesthetics and functionality into a sweater – a sweater that can double as a WiFi signal booster,” he concluded in the press release.