Ting Leng

Binder-free highly conductive graphene laminate for low cost printed radio frequency applications

In this paper, we demonstrate realization of printable radio frequency identification (RFID) antenna by low temperature processing of graphene ink. The required ultra-low resistance is achieved by rolling compression of binder-free graphene laminate. With compression, the conductivity of graphene laminate is increased by more than 50 times compared to that of as-deposited one. Graphene laminate with conductivity of 4.3 × 104 S/m and sheet resistance of 3.8 Ω/sq (with thickness of 6 μm) is presented. Moreover, the formation of graphene laminate from graphene ink reported here is simple and can be carried out in low temperature (100 °C), significantly reducing the fabrication costs. A dipole antenna based on the highly conductive graphene laminate is further patterned and printed on a normal paper to investigate its RF properties. The performance of the graphene laminate antenna is experimentally measured. The measurement results reveal that graphene laminate antenna can provide practically acceptable retur...

Highly Flexible and Conductive Printed Graphene for Wireless Wearable Communications Applications

In this paper, we report highly conductive, highly flexible, light weight and low cost printed graphene for wireless wearable communications applications. As a proof of concept, printed graphene enabled transmission lines and antennas on paper substrates were designed, fabricated and characterized. To explore its potentials in wearable communications applications, mechanically flexible transmission lines and antennas under various bended cases were experimentally studied. The measurement results demonstrate that the printed graphene can be used for RF signal transmitting, radiating and receiving, which represents some of the essential functionalities of RF signal processing in wireless wearable communications systems. Furthermore, the printed graphene can be processed at low temperature so that it is compatible with heat-sensitive flexible materials like papers and textiles. This work brings a step closer to the prospect to implement graphene enabled low cost and environmentally friendly wireless wearable communications systems in the near future.

Graphene Nanoflakes Printed Flexible Meandered-Line Dipole Antenna on Paper Substrate for Low-Cost RFID and Sensing Applications

In this letter, a graphene nanoflakes printed antenna is presented. Graphene nanoflakes conductive ink has been screenprinted on paper substrate and compressed to achieve the conductivity of 0.43 × 105 S/m. Low-profile meandered-line dipole antenna has been fabricated as a proof of concept due to its electrically small size and simple structure. The maximum gain is measured to be -4 dBi, the -10-dB bandwidth ranges from 984 to 1052 MHz (6.67%), and the radiation pattern is verified as being typical radiation patterns of a dipole-type antenna. The radiation efficiency is 32%. The measurement results reveal that graphene nanoflakes printed antenna can provide practically acceptable return loss, gain, bandwidth, and radiation patterns for midand short-range RFID, and sensing applications. Furthermore, screenprinting technique employed in this work is of extremely low cost and capable of producing antennas in mass production.

Graphene radio frequency and microwave passive components for low cost wearable electronics

Graphene RF and microwave passive components such as coplanar waveguide transmission lines, open/short-circuited resonators and wideband antenna on paper substrate were designed, screen printed and characterized in this work. The experimental results demonstrate that the screen printed graphene passive components can be used for RF signal transmitting, processing and radiating/receiving; revealing that graphene ink can be a low cost alternative to much more expensive metal nanoparticle inks, such as silver nanoparticle ink. The screen printed graphene is processed at low temperature so that it is compatible with heat-sensitive flexible materials like papers, PTFE (Polytetrafluoroethylene) and textiles. The screen printed graphene passive components reported here are of high conductivity, high flexibility, light weight and low cost, making them ideal candidate for low cost wearable electronics. This work makes it prospective to manufacture RF and microwave passive components in mass production by screen printing in much lower cost to any other known techniques.

Design and modeling of back gated graphene based RF switch with CPW transmission line on a high resistivity silicon substrate

This paper presents a design of transmission line based RF switch with graphene. The on-off states of the switch can be adjusted electrically due to the unique properties of monolayer graphene. The transmission between two ports varies more than 30dB when voltage changes from 0 to 30 V. The RF switch provides enough insertion loss and good isolation in on and off states.

Graphene reconfigurable coplanar waveguide (CPW)-fed circular slot antenna

We report the initial study of the reconfigurable antenna composed of graphene, in which a coplanar waveguide (CPW)-fed circular slot antenna is presented. The simple circular antenna made of copper is connected with the graphene slot by a short circuiting stub, where the graphene slot can be tuned by DC voltage bias. When the graphene acts the metallic conductor or the lossy dielectric with different DC bias setting, the effective length of the proposed antenna is changed, as well as the resonant frequency. The attractive properties of the proposed antenna can find its applications for future graphene multi Terabit wireless data transmission and transparent all-graphene sensing systems.

Reconfigurable dipole antenna design using graphene based switich

This paper presents the design of a reconfigurable antenna design using graphene based switch, where its working frequencies can be adjusted by switching between on/off states. The switching comes from the varying conductivity of graphene biased by external voltage. The working frequency moves from 838 MHz to 1.588 GHz when voltage is applied to change chemical potential in the range from 0 to 0.8eV. The promising results provide an alternative using graphene in frequency reconfigurable antennas.

Design of reconfigurable planar antenna using graphene based switch

This paper presents the design of a reconfigurable planar antenna design using graphene based switch, where its working frequencies can be adjusted by applying different voltages to connect or disconnect four patch sections to a midsection of the planar antenna. The switching comes from the varying chemical potential in the range from 0 to 0.8eV of graphene biased by external voltage. The promising results provide an alternative using graphene in frequency reconfigurable antennas.

Graphene array based beam-scanning terahertz antenna

In this paper, we present the concept and design of beam scanning terahertz antenna based on graphene arrays. The main lobe direction is verified to be scannable with flexibility introduced by graphene. The working principle of the beam scanning is further studied based on secondary reflection theory. This work can be further extended to flexible metasurface/coding metamaterial based antennas with graphene.