ArticlePDF Available

Optimization of Inkjet Printing of Patch Antennas on Low-Cost Fibrous Substrates


Abstract and Figures

In this letter, the inkjet-printing procedure is used to implement microwave circuits on low-cost fibrous substrate, cardboard. As a first step for environmentally friendly electronics applications, the high-frequency properties of the cardboard substrate are extracted using the two-transmission-line method and dielectric probe measurement. To provide an accurate model for the inkjet-printed conductors, the conductivity and thickness of the printed silver traces are analyzed. The surface of the substrate is pretreated using a dielectric ink to reduce the penetration of the conductor ink into the fibrous substrate and to diminish the conductor loss at high frequencies. As a technology demonstrator, a patch antenna is printed on a cardboard substrate, and the simulation and measurement results are compared to study the reliability of the obtained parameters. After initial experimental verification, simulation models were fine-tuned in order to provide a predictive method for design and fabrication of low-cost RF circuits. The achieved model can be used to design and fabricate low-cost RF structures on fibrous environmentally friendly substrates .
Content may be subject to copyright.
Optimization of Inkjet Printing of Patch Antennas on
Low-Cost Fibrous Substrates
Hossein Saghlatoon, Lauri Sydänheimo, Member, IEEE, Leena Ukkonen,Member,IEEE,and
Manos Tentzeris, Fellow, IEEE
Abstract—In this letter, the inkjet-printing procedure is used
to implement microwave circuits on low-cost brous substrate,
cardboard. As a rst step for environmentally friendly electronics
applications, the high-frequency properties of the cardboard sub-
strate are extracted using the two-transmission-line method and
dielectric probe measurement. To provide an accurate model for
the inkjet-printed conductors, the conductivity and thicknessof
the printed silver traces are analyzed. The surface of the substrate
is pretreated using a dielectric ink to reduce the penetration of
the conductor ink into the brous substrate and to diminish the
conductor loss at high frequencies. As a technology demonstrator,
a patch antenna is printed on a cardboard substrate, and the
simulation and measurement results are compared to study the
reliability of the obtained parameters. After initial experimental
verication, simulation models were ne-tuned in order to provide
a predictive method for design and fabrication of low-cost RF
circuits. The achieved model can be used to design and fabri-
cate low-cost RF structures on brous environmentally friendly
Index Terms—Dielectric characterization, green electronics,
inkjet printing, low-cost substrate, paper RF, patch antenna, silver
ink, surface treatment, two transmission lines method.
AS AN organic substrate, paper has a great potential for
the realization of environmentally friendly and recyclable
electronics [1], [2]. It is tempting to use paper as a substrate
for electronic circuits because it is ultra-low-cost, recyclable,
available everywhere, and compatible with printing [3]. Addi-
tive printing technologies, such as inkjet printing, feature the
capability to increase the fabrication speed and enhance the pro-
duction versatility, both features that are critical for mass pro-
duction. Moreover, inkjet printing has been an enabling tech-
nology to print electronics on unconventional substrates such
as wood, ceramic, and paper [3]–[5]. The electrical properties of
the low-cost brous types of paper, such as cardboard, should be
characterized, especially in microwave frequencies because the
RF properties of different paper materials are not identical [3].
In addition, it is challenging to effectively fabricate circuits on
Manuscript received December 13, 2013; revised February 20, 2014 and
April 04, 2014; accepted April 17, 2014. Date of publication May 08, 2014;
date of current version May 22, 2014.
H. Saghlatoon, L. Sydänheimo, and L. Ukkonen are with the TampereUniver-
sity of Technology, 33720 Tampere, Finland (e-mail: hossein.saghlatoon@tut.;
lauri.sydanheimo@tut.; leena.ukkonen@tut.).
M. M. Tentzeris is with the Georgia Institute of Technology, Atlanta, GA
30332-250 USA (e-mail:
Color versions of one or more of the gures in this letter are available online
Digital Object Identier 10.1109/LAWP.2014.2322572
brous substrates using inkjet printing because the printed ink
penetrates into the substrate and reduces the conductivity and
quality of the printed pattern [6].
In this letter, one typical cardboard paper material is used
as the substrate and silver nanoparticle ink as the conductor.
The rest of this letter is organized as follows. In Section II, the
specics of the cardboard electrical characterization technique
are discussed. Then, the measurement results for the conduc-
tivity, thickness, and surface roughness of inkjet-printed silver
traces before and after treatment of the substrate are proposed
according to Section III. Section IV discusses the design of a
patch antenna according the obtained parameters, and the effect
of inaccuracies in the fabrication and measurement procedures.
Finally, conclusions are presented in Section V.
To enable the effective implementation of efcient microwave
structures on a cardboard substrate, its RF properties have to be
measured and analyzed. There are different ways to characterize
an unknown substrate such as split-cylinder resonator, ring
resonator, and other high- structures [7], [8]. One of the most
accurate methods is the two-transmission-line method. In this
method, two identical microstrip lines with different lengths are
implemented on the substrate. The effective permittivity
of the substrate can be obtained from the phase difference of the
signals, and the loss tangent is acquired from the insertion loss. It
is not necessary to de-embed the effect of SMA connectors and
junctions because all the calculations are based on the transmis-
sion-line length difference effectively removing these parasitic
effects [8], [9]. Using (1) and (2) the effective permittivity and
total loss can be calculated, respectively
where is the free-space speed of light, is the phase dif-
ference of the output signals for the long and the short lengths,
is the frequency, and is the length difference of the two
microstrip lines [8], [10].
By knowing the total loss and conductor loss, the dielec-
tric loss and then the loss tangent can be determined. The total
loss is the summation of dielectric loss, conductor loss, and ra-
diation loss. The radiation loss is very low and can be neglected
from the calculations because the lengths of the lines are rela-
tively small. In this case, to have a high efcient traveling wave
1536-1225 © 2014 IEEE. Personal use is permitted, but republication/redistribution requires IEEE permission.
See for more information.
Fig. 1. Implemented microstrip lines on cardboard.
antenna, the length of the lines should be to . The con-
ductor loss is dependent on the physical properties of the con-
ductor, such as the conductivity and the width of the line. If the
properties of the conductor are known, the conductor loss is ap-
parent. The conductor loss of a certain transmission line can be
obtained using
where is the angular frequency, is the conductivity of the
conductor, is the characteristic impedance of the line, and
is the width of the microstrip line. Moreover, the loss tangent
can be obtained using (5) which is valid for microstrip lines [10]
where is the dielectric loss, is the relative permittivity
of the substrate, is the effective relative permittivity of the
substrate, and is the phase constant in free space [10].
For the characterization of the highly brous cardboard (Stora
Enso packaging thin paper), three microstrip lines with 15-, 10-,
and 5-cm lengths were realized on its surface utilizing a 50-
m-thick copper tape with bulk conductivity of S/m, ter-
minated in 50- SMA conductors, and having the same width of
2 mm for a characteristic impedance of 50 , as shown in Fig. 1.
Thelongestlineisalmost ; hence, the assumption for low
radiation loss is acceptable. For higher measurement reliability,
-parameters for the three different lengths were compared one
by one utilizing an Agilent PNA E8358A two-port vector net-
work analyzer (VNA) between 500 MHz and 3 GHz. To realize
the accuracy of this method, the relative permittivity and loss
tangent were measured using Agilent 85070 Dielectric Probe
Kit in the same frequency interval. The results for the average
permittivity and loss tangent of the substrate using these two
methods are depicted in Fig. 2. The results are in a sufciently
good agreement. Depending on the density and water content of
cardboard, its permittivity can vary between 1.2 and 1.5 [11].
The next important step for the inkjet printing of RF struc-
tures on cardboard is the characterization of the conductivity
and the realized thickness of the printed conductive traces.
NPS-JL silver ink with 55.5wt% metal content was used to
print using Dimatix DMP-2831 inkjet material printer. The
volume and diameter of each droplet was 10 pL and 140 m,
Fig. 2. Measured properties of cardboard. (a) Relative permittivity. (b) Loss
Fig. 3. Fabricated inkjet microstrip lines on cardboard.
respectively. To optimize the conductivity value, a sintering
process at 150 for 1 h with air circulation was applied, and
each RF pattern was printed [12]. For appropriate conductivity,
each pattern was printed in four cycles. In each cycle, two
layers of silver ink were printed and sintered, so at the end there
were eight layers of silver ink with the total thickness of 3 m
on cardboard.
Following this process, three microstrip lines with different
lengths were printed on cardboard as shown in Fig. 3. The di-
mensions of these lines are identical to the copper tape versions
for the purpose of easier comparison. In this case, the dielectric
loss is known, and by measuring the total loss, the conductor
loss can be obtained. The acquired value for the conductivity of
these structures is S/m.
Considering the cardboard substrate, there are numerous rea-
sons that led to a reduced value of conductivity compared to the
maximum achievable value S/m presented by the
manufacturer. These include the lower realized conductor thick-
ness compared to the skin depth and the high surface roughness.
The thickness of the printed silver ink on cardboard was mea-
sured using an optical microscope. The ink penetrates into the
cardboard due to its highly brous nature [6]. By penetration
of the ink into the brous substrate, the conductivity diminishes
because the printed silver nanoparticles cannot make a uniform
conductor. In addition, cardboard is not a good thermal con-
ductor; hence, in the sintering process, the printed silver ink is
not cured properly. Therefore, there is a demand to make the
surface smooth and ink proof. It can be easily seen in Fig. 4
that without a surface treatment approach, the ink penetration
into the substrate is around 55 m. Usually, different dielec-
tric inks are utilized to treat the surface [13], [14]. We used
a conventional primer (composed of tetrahydrofurfuryl acry-
late, ethoxylated trimethylolpropane triacrylate, 2-hydroxy-2-
methyl-1-phenyl-propan-1-one, and bis-phenylphosphineoxide
Fig. 4. Measured thickness of the ink (a) after treatment and (b) before
Fig. 5. Scanned surface of cardboard using optical prolometer. (a) Before
treatment. (b) After treatment.
[6]) to prepare a smooth surface for silver ink [6]. For this pur-
pose, four layers of primer with 1016 dpi resolution were printed
separately on the rough surface of cardboard. After the printed
deposition of each layer, it was cured using ultraviolet light
(UV) for 15 min, and then 1 h at 150 in an oven. Afterwards,
silver ink was inkjet-printed on the treated surface utilizing the
conventional sintering approach.
The surface roughness of the printed silver ink on the treated
and untreated cardboard was scanned using an optical pro-
lometer with results shown in Fig. 5. As can be deduced,
the peak-to-valley distance is around 39 m before treatment,
whichisimprovedto11.5 m after treatment. Moreover,
the mean roughness and root mean squared roughness are
improved from 1.68 and 2.13 m before treatment to 1.3 and
1.62 m after treatment, respectively. After the preparation
of the smooth and ink-proof surface, the same microstrip
lines were printed to analyze the new value of conductivity,
which was found to be almost double S/m .The
other important parameter for the printed silver ink traces for
high-frequency designs is the conductor thickness uniformity.
The cross section of the treated cardboard with printed silver
ink is shown in Fig. 4. As can be seen, the thickness is almost
uniform in the whole printed area and equal to 3 m.
Fig. 6. Conguration of the inkjet-printed patch antenna on cardboard.
Fig. 7. Simulation and measurement results for the proposed antenna. (a) Ra-
diation efciency. (b) Radiation gain. (c) Return loss.
As a proof of concept and without loss of generality, a mi-
crostrip patch antenna for 2.45 GHz with inset feeding was de-
signed for the acquired properties of the cardboard and of the
silver ink traces presented in Table I. The antenna is designed to
operate in the excitation mode, and its dimensions are
shown in Fig. 6.
This conguration was simulated using the 3-D full-wave
electromagnetic simulator Ansys HFSS based on nite element
method, while the inkjet-printed prototype was measured using
the near-eld measurement equipment Satimo Starlab. The sim-
ulation and measurement results for the radiation gain, radiation
efciency, and return loss are shown in Fig. 7. As can be seen,
there are slight discrepancies between the simulation and mea-
surement results. We believe these discrepancies arise due to
layer-to-layer alignment error and printer tolerances m .
However, it can be observed that this phenomenon increases the
Fig. 8. (a) Current distribution in the patch antenna at 2.45 GHz. (b) Misalign-
ment of the printed layers.
Fig. 9. Simulation and measurement results with the optimized model. (a) Ra-
diation efciency. (b) Radiation gain. (c) Return loss.
losses in the radiating edges of the patch antenna and of the
feeding line.
The results for the measured misalignment of different layers
using an optical microscope and for the simulated of the cur-
rent distribution magnitude are shown in Fig. 8. As can be seen
in Fig. 8(b), the misalignments of different layers are approxi-
mately in the range of 130 m and shown with the red shift. To
compensate for the effect of misaligned layers in the simulation
model, the conductivity of the radiating edges and of the feeding
line edges is reduced. The width and conductivity of the added
part in the simulations is 130 mand S/m. The afore-
mentioned two-transmission-line method was used to measure
the conductivity of the misaligned part.
Fig. 9 depicts the simulation results for the radiation ef-
ciency, radiation gain, and return loss for the new corrected
model. With this model, the matching between the simulated
and measured efciency is improved by 1.5%, and the gain by
1 dB. Another potential source of measurement error is the inac-
curacy of the near-eld measurement device, which is dB
for the peak gain at 1880 MHz. Compared to the simulation
model, the roughness of the printed structure is another source
of error that will be modeled in the further studies.
We have presented a novel method for the optimization of
inkjet printing of RF structures on brous substrates. As a proof
of concept, the properties of a typically highly brous card-
board substrate as well as of the inkjet-printed silver traces are
accurately characterized up to 3 GHz. A smoothness/substrate
hermeticity enhancing approach for the cardboard is presented,
and numerous uncertainties of inkjet printing approach are mod-
eled. The acquired values for the permittivity and loss tangent
of the cardboard, as well as the thickness and the conductivity
values for the printed silver traces are 1.78, 0.025, 3 m, and
S/m, respectively. Based on the developed method, a
patch antenna is simulated, fabricated with inkjet printing on
cardboard, and then measured. Finally, the simulation and mea-
surement results were compared, and acceptable agreement is
achieved. It can be concluded that the optimized model for card-
board and silver ink can be used in the fabrication and optimiza-
tion of RF structures on ultra-low-cost highly brous substrates,
such as cardboard.
[1] S. Palacios et al., “Inkjet-printed planar antenna for a wireless sensor
on paper operating at wi-frequency,” in Proc. IEEE APSURSI,Jul.
2012, pp. 1–2.
[2] M. Irimia-Vladu, “Green electronics: biodegradable and biocompatible
materials and devices for sustainable future,Chem.Soc.Rev., vol. 43,
no. 2, pp. 588–610, 2014.
[3] L.Yang,A.Rida,R.Vyas,andM.M.Tentzeris,“RFIDTagandRF
structures on paper substrates using inkjet-printing technology,” IEEE
Trans. Microw. Theory Tech., vol. 55, no. 12, pp. 2894–2901, Dec.
[4] J. Virkki, J. Virtanen, L. Sydanheimo, L. Ukkonen, and M. M.
Tentzeris, “Embedding inkjet-printed antennas into plywood struc-
tures for identication and sensing,” in Proc. IEEE RFID-TA, Nov.
2012, pp. 34–39.
[5] A.A.Babaret al., “Inkjet-printable UHF RFID tag antenna on a ex-
ible ceramic-polymer composite substrate,” in IEEE MTT-S Microw.
Symp. Dig., Jun. 2012, pp. 1–3.
[6] A.Denneulin,J.Bras,A.Blayo,andC.N.Neuman,“Substratepre-
treatment of exible material for printed electronics with carbon nan-
otube based ink,” Appl. Surface Sci., vol. 257, no. 8, pp. 3645–3651,
[7] L. Yang and M. M. Tentzeris, “Design and characterization of
novel paper-based inkjet-printed RFID and microwave structures for
telecommunication and sensing applications,” in Proc. IEEE MTT-S
Int. Microw. Symp., Jun. 2007, pp. 1633–1636.
[8] S.H.Chang,H.Kuan,H.W.Wu,R.Y.Yang,andM.H.Weng,“De-
termination of microwave dielectric constant by two microstrip line
method combined with EM simulation,” Microw. Opt. Technol. Lett.,
vol. 48, no. 11, pp. 2199–2201, 2006.
[9] N.K.Das,S.M.Voda,andD.M.Pozar,“Twomethodsforthemea-
surement of substrate dielectric constant,” IEEE Trans. Microw. Theory
Tech., vol. MTT-35, no. 7, pp. 636–642, Jul. 1987.
[10] D. M. Pozar, Microwave Engineering, 1st ed. New York, NY, USA:
Wiley, 1990, ch. 4, pp. 126–204.
[11] M. Sivakumar and D. D. Deavours, “A dual-resonant microstrip an-
tenna for paperboard in the cold chain,” in Proc. IEEE Sarnoff Symp.,
2008, pp. 1–5.
[12] Harima, “NPS-JL silver nanoparticle ink,” NanoPaste Series, Metal
Paste for Thin Film Formation, Datasheet, 2012.
[13] R. Bollström et al., “A multilayer coated ber-based substrate suit-
able for printed functionality,” Organic Electron., vol. 10, no. 5, pp.
1020–1023, 2009.
[14] S. M. Hurst, B. Farshchian, J. Choi, J. Kim, and S. Park, “A univer-
sally applicable method for fabricating superhydrophobic polymer sur-
faces,” Colloids Surfaces A, Physicochem. Eng. Aspects, vol. 407, pp.
85–90, 2012.
... In [10], time-to-market solution for reducing the production time in patch antenna designs is presented which is based on the inkjet printing to fabricate emitters. Respectively, in another work ( [11]) an optimization method is presented for employing it in the inkjet printing of RF structures. This procedure is applied by using one typical cardboard paper material as a substrate and a silver nanoparticle ink as the conductor which results in implementing microwave circuits on ultra-low-cost highly fibrous substrates. ...
... Please refer to [20] to the expanded formulations of these terms. Then the new output response is predicted using the Gaussian distribution as defined in (11)(12) with a kernel function of K(x, x ), a mean m(x), and a standard deviation σ(x). The general GP model with training data (i.e., D 0 = x i , y i ) is shown in Fig. 11. ...
Due to the exponential growth of data communications, millimeter -wave (mm-Wave) new radio specification becomes key enablers for fifth generation (5G) communication systems. However in the mmWave band frequency, the propagation loss is intensively large and cannot cover all the determined specifications. To tackle this drawback, the transceiver parts must sense the high radiated output power from power amplifiers. Hence by using high performance wideband antennas, the amplifiers can facilitate massive multiple-input multiple-output (MIMO) 5G systems. The figure of merit (FoM) of an amplifier is determined by the output power that must be challenged by other design specifications as: power gain, drain efficiency, and linearity. Therefore, powerful multiobjective optimization methods are required for welcoming appointed passive (antennas) and active (power amplifiers) characteristics in the determined frequency band. On the other side, high performance antennas in the 5G networks are also needed that can be designed using potent optimization methods. In this chapter, we provide collection of various optimization methods which have been recently applied for designing and optimizing high performance high power amplifiers and antennas. Hence, any designer can access to the nominated algorithms and can select the ones that are suitable for their problems.
... Heat conservation within the cavity can be written as: [19], [20], [21], [22], [23], [24], [25], [26], [27] where Q is the energy of heat, H is the heat flux vector and the thermal energy, E TH , is given by ...
Full-text available
Microwave heating of waste results in chemical breakdown that can lead to conversion of mixed waste materials to fuel. Heating waste mixtures with microwave energy rather than incineration results in faster breakdown and can therefore be more efficient. Here we address heating of small volumes of mixed food waste materials with widely differing and temperature-dependent electrical properties. Uniform heating is accomplished with mode mixing within a loaded cavity and by spatial power combining of solid-state power amplifiers (SSPAs). We present a heating comparison of two circuit-combined and spatially-combined 2.45 GHz 70-W 65% efficient GaN SSPAs with controlled relative phase. The heating efficacy is shown to improve by volumetric combining inside the waste loading. The temperature changes in several locations and for several common waste materials and mixtures are investigated and compared to FEM electromagnetic simulations, as well as FDTD multi-physics simulations that incorporate thermal dependence of material properties. The approach is scalable in volume and power, demonstrated by a simulation comparison of the 1.4 L small cavity to a 5.2 L volume.
Full-text available
Radio frequency energy harvesting (RFEH) systems have emerged as a critical component for powering devices and replacing traditional batteries, with paper being one of the most promising substrates for use in flexible RFEH systems. However, previous paper-based electronics with optimized porosity, surface roughness, and hygroscopicity still face limitations in terms of the development of integrated foldable RFEH systems within a single sheet of paper. In the present study, a novel wax-printing control and water-based solution process are used to realize an integrated foldable RFEH systems within a single sheet of paper. The proposed paper-based device includes vertically layered foldable metal electrodes, a via-hole, and stable conductive patterns with a sheet resistance of less than 1 Ω sq-1 . The proposed RFEH system exhibits an RF/DC conversion efficiency of 60% and an operating voltage of 2.1 V in 100 s at a distance of 50 mm and a transmitted power of 50 mW. The integrated RFEH system also demonstrates stable foldability, with RFEH performance maintained up to a folding angle of 150°. Our single-sheet paper-based RFEH system thus has the potential for use in practical applications associated with the remote powering of wearable and Internet-of-Things devices and in paper electronics. This article is protected by copyright. All rights reserved.
Coplanar stripline (CPS) series-connected spurline resonators are terminated with diodes, which can have a voltage applied to them, creating either a short circuit or open circuit. By connecting two spurline resonators in series separated by a quarter-wavelength transmission line, and when the diodes are reverse biased, the total circuit passes the RF power unimpeded. When the diodes are forward-biased, the circuit is a bandstop filter. This creates a CPS RF series switch with an insertion loss of 0.1 $\pm$ 0.1 dB, a reflection coefficient of $-$ 30 dB, and an isolation of 20 dB. The switch was simulated, fabricated, and measured for both single-element and two-element configurations.
Printed electronics (PE) is one of the most dynamic technologies in the world. It proposes low-cost electronic network production in flexible substrates by numerous printing techniques, (screen printing, gravure, offset, flexographic, and inkjet printing), used in various industries. In PE, ink pigments are replaced by metallic particles or precursors that transmit electrical conductivity to the printed patterns such as carbon, polymers and conductive pigments. Conductive inks play an important role in printed electronics, and despite the number of conductive ink types available on the market, there are still issues to be addressed. Some of these restrictions include the use of toxic chemical reagents and solvents and complicated manufacturing protocols, which often make the industrialization of conductive inks an even more distant goal. In particular, conductive inks based on silver nanoparticles, Graphene and PEDOT:PSS are widely studied thanks to their high electrical conductivity. On the other hand, there is still work to be done to show the interest of inks based on phthalocyanine pigments, in particular copper phthalocyanine. Nevertheless, problems related to stability, dispersion and annealing temperature often limit the application of these four types of fillers. In this review, we present general information on available conductive fillers used for the formulation of conductive inks, focusing on metallic particles, carbon fillers, pigments and polymers. The influence and technical requirements of the regularly used printing techniques, as well as the post-processing treatments to achieve the targeted performance in the obtained inks have been discussed. In addition, the surface characteristics of the various types of extensible and flexible substrates used in portable electronics are described. Moreover, some types of printed flexible electronic components as well as notable applications of electronic textiles in various sectors are exhibited. Next, the major challenges for the manufacturing of printed flexible electronics and recommendations for future research are discussed in this review
There is widespread use of telecommunication and microwave technology in modern society, and raised the Electromagnetic (EM) interference (EMI) issue to alarming situation due to apprehensive demand and growth of 5G technology undesirably disturbing the human health. The 2D materials including graphene and MXenes are already been used for variety of electronic devices due to their exceptional electrical, mechanical, optical, chemical, and thermal properties. MXene is composed of metal carbides, in which mainly metals are the building blocks for dielectrics, semiconductors, or semimetals. However, the strong interfaces with electromagnetic waves (EM) are variable from terahertz (THZ) to gigahertz (GHZ) frequency levels and are widely used in electromagnetic interference shielding (EMI) and Microwave absorption (MA) for mobile networks and communication technologies. This research work is a comprehensive review majorly focuses on the fundamentals of Electromagnetic shielding (EMI)/microwave absorption (MA). The use of different organic materials with metal, organic, inorganic fillers, polymers nanocomposite and MXene as a novel material has been studied to address the recent advancement and challenges in the microwave absorption mechanism of 2D materials and their nanocomposites. In this concern, various techniques and materials has been reported for the improvement of shielding effectiveness (SE), and theoretical aspects of EMI shielding performance, as well stability of two dimensional (2D) materials particularly MXenes and its nanocomposites. Consequently, various materials including polymers, conducting polymers, metal-organic frameworks (MOF) have also been discussed by introducing various strategies for improved microwave (MA) and control of EMI shieling. Here in this comprehensive review, we summarized the recent developments on material synthesis and fabrication of MXene based nanocomposites for EMI shielding and Microwave absorption. The recent developments and challenges of the MXene based various structures with different polymeric composites are described in a broader perspective.
Fifth Generation (5G) communication tools are extremely important for the modern society, especially when more and more of our activities are organized in such a way as to be carried out rapidly and more efficiently even if they are to take place from a distance. There are many possibilities, using different advanced materials, to fulfill the high demand of the antennas with different functionalities. Investigation on the characteristics of the material used in this application is a starting point to be really able to manage in a proper way the performance of the antenna. Understanding the most important characteristics allows designing material with low or even controlled dispersion that intrinsically will increase the performance of the antenna. The present chapter reports some fundamental elements belonging to such a wide-ranging topics used up to date, even if it does not target to fully cover all features about any material used in this field. The aim of the present chapter is to present different challenges in designing 5G communication tools, starting from the selection of the appropriate material up to their production methods. It also includes some aspects related to the multidisciplinary face of such research developments in order to highlight the necessity of the participation of many scientific figures to attain enhanced characteristics of the future communication systems. Additionally, an insight into future communication networks from material point of view is provided. Some of the major challenges in THz communications, body implant antennas and wearable antennas are discussed also. © 2022, The Author(s), under exclusive license to Springer Nature Switzerland AG.
There has been a steadily increasing demand for higher bandwidths in modern communication systems, which in turn has led these systems to gravitate to higher frequencies, e.g., the Ka-band, for the fifth generation (5G) systems. Beam scanning is an essential feature of the 5G systems since it helps to improve the power efficiency as well as wide-angle scan capability. Typically, phased array antennas are widely used for the purpose of beam scanning; however, the phased arrays suffer from the disadvantages of design complexity, large bulk, appetite for high power consumption, and requirement for a large-size real estate to accommodate them, especially when their gain requirement is high. The design process for the array becomes even more complex when the array needs to be mounted conformally to the platform, and multiple approaches for alternate designs for such antenna arrays have been proposed in the literature. In this chapter, first, we begin by discussing the Gradient-index lens (GRIN)—specifically the Luneburg lens—which provides a good alternative to the conformal phased array. We show that the Luneburg lens is useful for multi-beam, wide-angle, low-cost, and wideband communication applications. Next, we discuss a general-purpose technique to design conformal antenna arrays with ultra-wide-angle scan capabilities. All the designs proposed herein provide wide-angle beam-scanning, with low scan-loss, and are good candidates for 5G communication systems.
The nanofibrillated cellulose paper (nanocellulose paper or nanopaper), which is flexible, transparent, ultrasmooth, and biodegradable, has emerged as a new substrate material for the next generation of paper-based flexible electronics. This paper reports a visible light-induced printing technique for depositing highly conductive silver (Ag) patterns on nanopaper. The optical Ag printing process is simple to implement at room temperature, and only requires nontoxic, low-cost aqueous chemical solutions and an inexpensive light projection setup. The abundant carboxyl groups on the nanopaper enables efficient absorption of Ag⁺ ions on the nanopaper surface for light-induced reduction of silver ions into a thin film of densely packed silver nanoparticles (AgNPs). Chemical annealing of the deposited AgNPs further enhances the conductivity of the printed Ag patterns. We characterized the mechanical and electrical properties of the printed Ag patterns on nanopaper, and also demonstrated the application of the optical Ag printing technique to fabricating nanopaper-based flexible circuits and electrochemical biosensors. We believe that he optical printing technique will enable new designs and applications of nanopaper-based flexible electronics. This article is protected by copyright. All rights reserved.
Conference Paper
Full-text available
Organic substrates is one of the leading solutions to realize ultra-low-cost and “green” wireless sensor applications. Inkjet printing on paper would be particularly economically appealing if commercial antennas could be replaced with printed antennas with similar performance. This paper presents the replacement of an inkjet-printed, planar, inverted-F antenna (PIFA) for a conventional commercially available, three dimensional (3D) monopole used in a Smart Wireless Integrated Module (SWIM). Both the sensor layout and PIFA antenna are inkjet-printed on paper substrate, in a first successful step towards the implementation of a fully operational, fully planar wireless sensor on paper at Wi-Fi frequency (2.4 GHz).
Conference Paper
Full-text available
The embedding of radio frequency identification (RFID) tags into plywood boards will enable the identification and tracking of individual plywood boards and end products of plywood. Even more benefits can be achieved by adding sensing functions into these tags. We present tags that are embeddable inside plywood by direct inkjet-printing on pure birch veneer. The use of passive UHF RFID technology in the plywood industry is discussed, two tag antenna designs for plywood are presented and the tag fabrication procedures are described. Furthermore, tag performance measurement results from various setups are presented to verify the concept of embedding RFID and sensor antennas into plywood structures. Measurements show that tags printed on veneer and embedded inside 2 mm thick plywood board exhibited theoretical read ranges from 7.9 meters to 10.3 meters. The read ranges obtained meet the demands of the plywood industry and offer reliable identification even in challenging environments.
Full-text available
"Green" electronics represents not only a novel scientific term but also an emerging area of research aimed at identifying compounds of natural origin and establishing economically efficient routes for the production of synthetic materials that have applicability in environmentally safe (biodegradable) and/or biocompatible devices. The ultimate goal of this research is to create paths for the production of human- and environmentally friendly electronics in general and the integration of such electronic circuits with living tissue in particular. Researching into the emerging class of "green" electronics may help fulfill not only the original promise of organic electronics that is to deliver low-cost and energy efficient materials and devices but also achieve unimaginable functionalities for electronics, for example benign integration into life and environment. This Review will highlight recent research advancements in this emerging group of materials and their integration in unconventional organic electronic devices.
Focusing on the design of microwave circuits and components, this valuable reference offers professionals and students an introduction to the fundamental concepts necessary for real world design. The author successfully introduces Maxwell's equations, wave propagation, network analysis, and design principles as applied to modern microwave engineering. A considerable amount of material in this book is related to the design of specific microwave circuits and components, for both practical and motivational value. It also presents the analysis and logic behind these designs so that the reader can see and understand the process of applying the fundamental concepts to arrive at useful results. The derivations are well laid out and the majority of each chapter's formulas are displayed in a nice tabular format every few pages. This Third Edition offers greatly expanded coverage with new material on: Noise; Nonlinear effects; RF MEMs; transistor power amplifiers; FET mixers; oscillator phase noise; transistor oscillators and frequency multiplier.
The utilization of inkjet-printing technique to develop a printable UHF RFID tag antenna on flexible ceramic-polymer composite material is demonstrated. The substrate material is fabricated using high permittivity Barium Titanate (BaTiO3) ceramic powder mixed with polydimethylsiloxane (PDMS) polymer. A UHF RFID tag antenna is inkjet-printed using silver nano-particle to exploit the potential advantages of high dielectric flexible composite material when used as a tag substrate. Our preliminary results yielded a small flexible UHF RFID tag antenna with read range comparable to commercially available tag antennas.
In this work, an innovative solution was developed in order to make paper-based material, used traditionally in the packaging and labelling industries, compatible with the printing of functional conductive inks. In order to avoid the deterioration of the ink functionalities due to different paper properties, a UV-curing inkjettable primer layer was developed. This pre-treatment enables homogeneous surface properties such as smoothness, absorption capacity and surface energy to be obtained, for almost all the examined substrates. To confirm the positive impact of such pre-treatment, conductivity has been measured when using a new conductive ink, combining the processability of the PEDOT–PSS conductive polymer with the high electrical properties of carbon nanotubes (CNTs). Significant improvement has been measured for all paper materials and similar conductivity (close to reference PET film) has been obtained whatever the substrate involved. This pre-treatment now makes it possible to consider paper-based material as a potential substrate for printed electronics. In this case, the substrate adaptation technique offers an innovative solution to produce low-cost and flexible electronics.
h i g h l i g h t s A simple method to produce super-hydrophobic surfaces in polymers was developed. This method was demonstrated for PMMA, PC and COC polymers. Surface morphology and wetting were studied as a function of O2 plasma time. The fabricated superhydrophobic surfaces were stable up to 90 days. g r a p h i c a l a b s t r a c t a b s t r a c t The modification of polymer surfaces to manipulate their wetting properties is of great technological importance. It is well known that surface chemistry and topography jointly determine the nature of wetting on a surface. In this study, we show a cheap and effective process universally applicable to fabricate superhydrophobic surfaces on various polymers. The process combines sanding and reactive ion etching treatment of the polymer surface to generate respective micro and nanoscale surface roughness, which is followed by subsequent coating of a fluorinated silane molecule to modify the surface chemistry. A 5 min reactive ion etching treatment after sanding is sufficient to achieve nanoscale roughness required for superhydrophobic surfaces. The polymer surfaces so produced retain their superhydrophobicity for more than 90 days, demonstrating the stability of the micro and nanoscale surface roughness and the hydrophobic surface coating. Similar results are obtained with different polymers such as poly(methyl methacrylate) (PMMA), polycarbonate (PC) and cyclo-olefin copolymer (COC), indicating that the process can be applied for creating superhydrophobic surfaces on general polymer substrates.
A recyclable multilayer coated fiber-based substrate combining sufficient barrier and printability properties for printed functional devices was developed using reel-to-reel techniques. The substrate consists of a mineral pigment layer coated on top of a barrier latex layer. The pigment layer allows controlled absorption of ink solvents. By adjusting the thickness and porosity of the top coating the printability can be tuned for various functional inks. As a proof of concept a hygroscopic insulator field effect transistor (HIFET) was successfully printed on the multilayer-coated paper.