Electromagnetic shielding of Optically-Transparent and Electrically-Insulating ionic solutions

Hong, Jun‐Pyo; Kwon, Jihoon; Iqbal, Aamir; Kim, Daesin; Kwon, Taehoon; Sambyal, Pradeep; Hong, Soon Man; Yoon, Ho Gyu; Kim, Myung‐Ki; Koo, Chong Min

doi:10.1016/j.cej.2022.135564

Cited by 17 publications

(20 citation statements)

References 36 publications

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“…This coordinated displacement of cations and anions in opposite directions created a local internal electromagnetic field, which destructively interfered with the incident EM field and caused excellent EM attenuation in CECs. 18–24 As can be seen in Fig. 3e, which depicts an absorption coefficient of more than 0.5 for all the composites, confirming the dominance of absorption shielding over reflection shielding in the total shielding performance.…”

Section: Resultssupporting

confidence: 60%

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Ionic liquid-dispersed PDMS/SWCNT/Ag@Ni hybrid composite for temperature- and pressure-sensitive smart electromagnetic shielding applications

et al. 2023

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Section: Resultssupporting

confidence: 60%

“…However, the entire loss in terms of dielectric and magnetic losses are defined in a single entity, i.e. , by the attenuation constant computed for all samples using eqn (1), as follows: 3,17,18 where f is the frequency and c is the light velocity. The concentration-dependent α results for the studied composites are displayed in Fig.…”

Section: Resultsmentioning

confidence: 99%

Ionic liquid-dispersed PDMS/SWCNT/Ag@Ni hybrid composite for temperature- and pressure-sensitive smart electromagnetic shielding applications

et al. 2023

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“…18 Hong et al showed that water significantly affects shielding performance through the polarization loss of the dipolar water molecule. 20 Yu et al also reported that the proportion of water plays an important role in the absorption performance of EMI shielding; that is, Ag@PPy sponge showed a reflection loss (RL) of ∼ −33 dB (at 8.8 GHz with a thickness of 3 mm) with a water content of 26.2% by weight. 21 Therefore, the water holding capacity of a hydrogel is a fundamental property that influences its other properties as well as application of EMI shielding.…”

Section: Introductionmentioning

confidence: 99%

“…In addition to this, water is also capable of generating polarization and attenuation losses in the gigahertz and terahertz range . Hong et al showed that water significantly affects shielding performance through the polarization loss of the dipolar water molecule . Yu et al also reported that the proportion of water plays an important role in the absorption performance of EMI shielding; that is, Ag@PPy sponge showed a reflection loss (RL) of ∼ –33 dB (at 8.8 GHz with a thickness of 3 mm) with a water content of 26.2% by weight .…”

Section: Introductionmentioning

confidence: 99%

Elastomer Encapsulated Silver Nanorod Dispersed Polyacrylamide-Alginate Hydrogel for Water-Pressure-Dependent EMI Shielding Application

Paria

Bera

et al. 2022

ACS Appl. Eng. Mater.

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Smart electromagnetic interference (EMI) shielding materials with tunable EMI shielding effectiveness (SE) have garnered huge attention in the fabrication of next generation EM devices as well as innovative wearable electronics. Here, we report a polydimethylsiloxane (PDMS) encapsulated soft, flexible, and stretchable polyacrylamide (PAM)-alginate (Alg)-hydrogel/silver nanorod (AgNR) composite system for EMI SE application. The PDMS encapsulation not only enhances the tensile strength of the system from ∼0.057 MPa to ∼0.724 MPa but also restricts the evaporation of water from the hydrogel matrix. Consequently, at 14.5 GHz frequency, the EMI SE (∼48.72 dB) of the hydrogel was reduced to ∼10.52 dB (72 h at 30 °C) and ∼6.44 dB (72 h at 40 °C) and ∼8.03 dB after 1 week of settlement at ambient conditions. However, for the encapsulated hydrogel, the EMI SE (∼40.65 dB) value was marginally reduced to ∼33.86 dB, ∼31.45 dB, and ∼32.42 dB, respectively, under the same conditions. Moreover, by changing the sample thickness (increasing holding pressure in a VNA sample holder), the shielding performance can be altered from ∼48.72 to ∼53.63 dB for the hydrogel and from ∼40.65 to ∼44.03 dB for the encapsulated hydrogel. Thus, these findings provide an innovative strategy to fabricate a flexible and stretchable EMI shielding material with adjustable SE by varying the content of water and applying pressure for futuristic development in smart electronics.

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“…Both electron transport and ion migration can form currents and cause EMW losses under alternating EM fields. [36][37][38] In the case of gels, the dielectric inert polymer networks contribute neither polarization nor conduction losses, and there is an extreme lack of free electrons in the internal liquid. Electronic conduction losses are ignored as a matter of course.…”

Section: Dielectric Properties and Mechanismsmentioning

confidence: 99%

Hydro/Organo/Ionogels: “Controllable” Electromagnetic Wave Absorbers

2022

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Demand for electromagnetic wave (EMW) absorbers continues to increase with technological advances in wearable electronics and military applications. In this study, a new strategy to overcome the drawbacks of current absorbers by employing the co‐contribution of functional polymer frameworks and liquids with strong EMW absorption properties is proposed. Strongly polar water, dimethyl sulfoxide/water mixtures, and highly conductive 1‐ethyl‐3‐methylimidazolium ethyl sulfate ([EMI][ES]) are immobilized in dielectrically inert polymer networks to form different classes of gels (hydrogels, organogels, and ionogels). These gels demonstrate a high correlation between their dielectric properties and polarity/ionic conductivity/non‐covalent interaction of immobilized liquids. Thus, the EMW absorption performances of the gels can be precisely tuned over a wide range due to the diversity and stability of the liquids. The prepared hydrogels show good shielding performance (shielding efficiency > 20 dB) due to the high dielectric constants, while organogels with moderate attenuation ability and impedance matching achieve full‐wave absorption in X‐band (8.2–12.4 GHz) at 2.5 ± 0.5 mm. The ionogels also offer a wide effective absorption bandwidth (10.79–16.38 GHz at 2.2 mm) via prominent ionic conduction loss. In short, this work provides a conceptually novel platform to develop high‐efficient, customizable, and low‐cost functional absorbers.

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Electromagnetic shielding of Optically-Transparent and Electrically-Insulating ionic solutions

Cited by 17 publications

References 36 publications

Ionic liquid-dispersed PDMS/SWCNT/Ag@Ni hybrid composite for temperature- and pressure-sensitive smart electromagnetic shielding applications

Ionic liquid-dispersed PDMS/SWCNT/Ag@Ni hybrid composite for temperature- and pressure-sensitive smart electromagnetic shielding applications

Elastomer Encapsulated Silver Nanorod Dispersed Polyacrylamide-Alginate Hydrogel for Water-Pressure-Dependent EMI Shielding Application

Hydro/Organo/Ionogels: “Controllable” Electromagnetic Wave Absorbers

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