Researchers have developed an computerized drawing machine that makes use of pens and pencils to attract metamaterials onto paper. They demonstrated the brand new method through the use of it to make three metamaterials that can be utilized to control the microwave area of the electromagnetic spectrum.
Metamaterials are artificially engineered composite supplies that derive their properties from patterned microstructures, fairly than the chemical composition of the supplies themselves. The precise form, geometry, dimension, orientation and association of the buildings can be utilized to control electromagnetic waves in ways in which aren’t potential with typical supplies.
“Metamaterials, particularly these used as absorbers, typically should be skinny, light-weight, extensive and powerful, but it surely is not simple to create skinny and light-weight units utilizing conventional substrates,” mentioned analysis group chief Junming Zhao from Nanjing College in China. “Utilizing paper because the substrate might help meet these necessities whereas additionally lending itself to metasurfaces that conform to a floor or which can be mechanically reconfigurable.”
Within the journal Optical Supplies Categorical, the researchers describe their new method, which makes use of aballpoint pen with conductive ink to attract conductors and mechanical pencils to attract resistors and resistive movies. They included this course of right into a computer-controlled drawing machine to make it extra computerized and correct.
“Though paper-based metamaterials have been made beforehand utilizing inkjet printing expertise, our drawing method is decrease price, less complicated and extra versatile,” mentioned Zhao. “Our technique may very well be helpful for making reconfigurable antennas and metalenses in addition to metamaterial units that take in incident electromagnetic power from cell telephones or different sources.”
The brand new drawing machine makes use of pens with ink containing conductive materials or regular mechanical pencils with various graphite content material. It has three stepper motors, two of which management the motion of the pen or pencil within the horizontal aircraft, whereas the opposite lifts or drops the writing instrument within the vertical aircraft. The parameters of the drawing machine, such because the motion pace, are managed by a pc.
“A number of the paper we tried was not very suitable with the pencils or conductive ink pens, leading to poor conductivity of the drawn patterns,” mentioned Zhao. “After some testing, we discovered the very best efficiency got here from utilizing paper that’s .22 mm thick, which is simple to acquire and really suitable with the pencils and conductive ink.”
The researchers used the conductive ink pen to attract patterns on paper and located the patterns to have a great conductivity of three×106 Siemens per meter. In addition they examined pencils with numerous quantities of graphite, drawing occasions and drawing pressures to characterize how these elements affected electrical resistance. This allowed them to calculate the circumstances wanted for drawing patterns with a particular resistance.
Creating paper metamaterials
Utilizing their new drawing method, the researchers designed and fabricated three totally different paper-based metamaterials: a polarization converter, an absorber and a conformal coding metasurface. They confirmed that the polarization converter may rotate linear polarization by 90° with a conversion effectivity of over 90% from 3.1 to six.6 GHz. The absorber they fabricated had a mass of simply 58.3 grams and achieved 90% absorptivity between 2.1 GHz to 10.5 GHz.
The researchers additionally created a conformal coding metasurface that may very well be used for radar cross-section discount, which is used to cover the radar sign in navy plane and ships. This metasurface had two structural items with a 180° reflection section distinction to one another, which allowed them to behave as ‘0′ and ‘1′ parts for 1-bit coding. When bent round a curved floor, this metasurface achieved a ten dB radar cross-section discount over a frequency band from 8.94 to 11.59 GHz.
“We hope that sooner or later, we will use the drawing expertise to design and fabricate meta-devices that may very well be carried or utilized to the pores and skin to realize electromagnetic shielding and different features,” mentioned Zhao. “We additionally plan to design mechanically reconfigurable metamaterials that make the most of the truth that paper could be bent and folded.”