Researchers have created an Automatic drawing machine that transfers metamaterials onto paper using pens and pencils. As an example of the new method, they used making three metamaterials that can be used to control the microwave part of the electromagnetic spectrum.
Metamaterials are synthetically created composite materials whose structured microstructures, rather than the materials’ chemical makeup, determine their properties. Because of their precise shape, size, orientation, and arrangement, the structures can be used to change electromagnetic waves in ways that aren’t possible with ordinary materials.
According to Junming Zhao, the head of the research team from Nanjing University in China, “Metamaterials, especially those employed as absorbers, normally need to be thin, lightweight, wide, and strong. However, it is difficult to construct thin and lightweight devices using traditional substrates. “Paper as the substrate can assist in achieving these needs while also lending itself to mechanically reconfigurable or surface-conforming metasurfaces.”
The researchers explain their automatic drawing machine method, which uses mechanical pencils to create resistors and resistive coatings and a ballpoint pen with conductive ink to create conductors, in the journal Optical Materials Express. They automated and improved this procedure by incorporating it into a computer-controlled drawing machine.
Although inkjet printing technology has been used in the past to create paper-based metamaterials, Zhao claims that his sketching method is more flexible, easier, and less expensive. Our method could be used to make antennas and metalenses that can be changed and metamaterials that can absorb electromagnetic radiation from cell phones or other sources.
Robotic sketching
The automatic drawing machine utilizes mechanical pencils with changing graphite content or conductive ink-containing pens. Three stepper motors are used; two are used to move the pen or pencil in a horizontal plane, and the third is used to lift or lower the writing instrument in a vertical plane. A computer regulates the drawing machine’s characteristics, including movement speed.
Zhao explained that some of the papers they tested did not work well with the pencils or conductive ink pens, which led to the sketched patterns having low conductivity. After some testing, we discovered that The best results were on 22 mm thick paper, which is accessible and works well with conductive ink and pencils.
The patterns that the researchers drew on paper with the conductive ink pen had a good conductivity of 3 106 Siemens per meter. Researchers also investigated these variables in order to understand how drawing times, drawing pressures, and pencils with different amounts of graphite affected electrical resistance. So, they were able to figure out what had to happen to make patterns with a certain resistance.
Making metamaterials from paper
The researchers created three distinct paper-based metamaterials: a polarization converter, an absorber, and a conformal coding metasurface using their novel sketching technique. They demonstrated that the polarization converter could rotate linear polarization by 90 degrees between 3.1 and 6.6 GHz with a conversion efficiency of over 90%. They created an absorber that weighed only 58.3 grams and had 90% absorptivity between 2.1 GHz and 10.5 GHz.
The researchers also developed a conformal coding metasurface for radar cross-section reduction, which is a technique for concealing the radar signal in ships and aircraft utilized by the military. This metasurface contained two structural units that were 180 degrees apart in terms of reflection phase, allowing them to serve as the “0” and “1” elements for 1-bit coding. This metasurface, when twisted around a curved surface, reduced the radar cross-section by 10 dB for the frequency range of 8.94 to 11.59 GHz.
Zhao said, “We anticipate using drawing technology to create meta-devices that might be worn or applied to the skin in the future to do many tasks, including electromagnetic shielding. We also want to make metamaterials that can be changed mechanically and are as flexible as paper. “
