Microwave absorption in radar stealth technology is faced with challenges in terms of its effectiveness in low-frequency regions.Herein,we report a new laser-based method for producing an ultrawideband metamaterial-ba...Microwave absorption in radar stealth technology is faced with challenges in terms of its effectiveness in low-frequency regions.Herein,we report a new laser-based method for producing an ultrawideband metamaterial-based microwave absorber with a highly uniform sheet resistance and negative magnetic permeability at resonant frequencies,which results in a wide bandwidth in the L-to S-band.Control of the electrical sheet resistance uniformity has been achieved with less than 5%deviation at 400Ωsq^(-1)and 6%deviation at 120Ωsq^(-1),resulting in a microwave absorption coefficient between 97.2%and 97.7%within a1.56–18.3 GHz bandwidth for incident angles of 0°–40°,and there is no need for providing energy or an electrical power source during the operation.Porous N-and S-doped turbostratic graphene 2D patterns with embedded magnetic nanoparticles were produced simultaneously on a polyethylene terephthalate substrate via laser direct writing.The proposed low-frequency,wideband,wide-incident-angle,and high-electromagnetic-absorption microwave absorber can potentially be used in aviation,electromagnetic interference(EMI)suppression,and 5G applications.展开更多
Electromagnetic interference shielding and thermal management by wearable devices show great po-tential in emerging digital healthcare.Conventional metal films implementing the functions must sacri-fice either flexibi...Electromagnetic interference shielding and thermal management by wearable devices show great po-tential in emerging digital healthcare.Conventional metal films implementing the functions must sacri-fice either flexibility or permeability,which is far from optimal in practical applications.In this work,an ultra-thin(15μm),flexible,and porous Cu/PLLA fibrous membrane is developed by depositing cop-per particles on the polymer substrate.With novel acetone&heat treatment procedure,the mem-brane is considerably stronger while maintaining the porous fibre structure.Its fantastic breathabil-ity and super high electrical conductivity(9471.8130 S/cm)enable the composites to have fast electri-cal heating characteristics and excellent thermal conductivity for effective thermal management.Mean-while,the porous polymer substrate structure greatly enhances the diffusion of conductive substances and increases the electromagnetic interference shielding effectiveness of the membranes(7797.98 dB cm^(2)/g at the H band and 8072.73 dB cm^(2)/g at the Ku band respectively).The composites present high flexibility,breathability,and strength with the functions of thermal management and electromag-netic shielding,showing great potential for future portable electronic devices and wearable integrated garments.展开更多
文摘Microwave absorption in radar stealth technology is faced with challenges in terms of its effectiveness in low-frequency regions.Herein,we report a new laser-based method for producing an ultrawideband metamaterial-based microwave absorber with a highly uniform sheet resistance and negative magnetic permeability at resonant frequencies,which results in a wide bandwidth in the L-to S-band.Control of the electrical sheet resistance uniformity has been achieved with less than 5%deviation at 400Ωsq^(-1)and 6%deviation at 120Ωsq^(-1),resulting in a microwave absorption coefficient between 97.2%and 97.7%within a1.56–18.3 GHz bandwidth for incident angles of 0°–40°,and there is no need for providing energy or an electrical power source during the operation.Porous N-and S-doped turbostratic graphene 2D patterns with embedded magnetic nanoparticles were produced simultaneously on a polyethylene terephthalate substrate via laser direct writing.The proposed low-frequency,wideband,wide-incident-angle,and high-electromagnetic-absorption microwave absorber can potentially be used in aviation,electromagnetic interference(EMI)suppression,and 5G applications.
基金We acknowledge the support of the Electron Microscopy Centre at The University of Manchester.
文摘Electromagnetic interference shielding and thermal management by wearable devices show great po-tential in emerging digital healthcare.Conventional metal films implementing the functions must sacri-fice either flexibility or permeability,which is far from optimal in practical applications.In this work,an ultra-thin(15μm),flexible,and porous Cu/PLLA fibrous membrane is developed by depositing cop-per particles on the polymer substrate.With novel acetone&heat treatment procedure,the mem-brane is considerably stronger while maintaining the porous fibre structure.Its fantastic breathabil-ity and super high electrical conductivity(9471.8130 S/cm)enable the composites to have fast electri-cal heating characteristics and excellent thermal conductivity for effective thermal management.Mean-while,the porous polymer substrate structure greatly enhances the diffusion of conductive substances and increases the electromagnetic interference shielding effectiveness of the membranes(7797.98 dB cm^(2)/g at the H band and 8072.73 dB cm^(2)/g at the Ku band respectively).The composites present high flexibility,breathability,and strength with the functions of thermal management and electromag-netic shielding,showing great potential for future portable electronic devices and wearable integrated garments.
