Stretchable, High‐<i>k</i> Dielectric Elastomers through Liquid‐Metal Inclusions

Bartlett, Michael D.; Fassler, Andrew; Kazem, Navid; Markvicka, Eric J.; Mandal, Pratiti

doi:10.1002/adma.201506243

Cited by 311 publications

(286 citation statements)

References 29 publications

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“…The LM embedded elastomer (LMEE) is composed of a Pt-catalyzed silicone elastomer embedded with a randomly distributed, polydisperse suspension of nontoxic (21), liquid-phase eutectic gallium−indium (EGaIn) microdroplets (19,20,22). As shown in Fig.…”

Section: Resultsmentioning

confidence: 99%

“…1 C and D). Previously, we showed that LM-embedded elastomers can be engineered to exhibit dramatic enhancements in electrical permittivity (19) and conductivity (20) without sacrificing the elastic properties of the matrix elastomer. A subsequent effort by another group attempted to show enhanced thermal conductivity with a polydisperse suspensions of irregularly shaped LM inclusions (12).…”

Section: ·Kmentioning

confidence: 99%

See 1 more Smart Citation

High thermal conductivity in soft elastomers with elongated liquid metal inclusions

Bartlett

Kazem

Powell‐Palm

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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478

429

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Soft dielectric materials typically exhibit poor heat transfer properties due to the dynamics of phonon transport, which constrain thermal conductivity (k) to decrease monotonically with decreasing elastic modulus (E). This thermal−mechanical trade-off is limiting for wearable computing, soft robotics, and other emerging applications that require materials with both high thermal conductivity and low mechanical stiffness. Here, we overcome this constraint with an electrically insulating composite that exhibits an unprecedented combination of metal-like thermal conductivity, an elastic compliance similar to soft biological tissue (Young's modulus < 100 kPa), and the capability to undergo extreme deformations (>600% strain). By incorporating liquid metal (LM) microdroplets into a soft elastomer, we achieve a ∼25× increase in thermal conductivity (4.7 ± 0.2 W·m ) under stress-free conditions and a ∼50× increase (9.8 ± 0.8 W·m) when strained. This exceptional combination of thermal and mechanical properties is enabled by a unique thermal−mechanical coupling that exploits the deformability of the LM inclusions to create thermally conductive pathways in situ. Moreover, these materials offer possibilities for passive heat exchange in stretchable electronics and bioinspired robotics, which we demonstrate through the rapid heat dissipation of an elastomer-mounted extreme high-power LED lamp and a swimming soft robot.liquid metal | thermal conductivity | soft materials | soft robotics | stretchable electronics

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Section: Resultsmentioning

confidence: 99%

Section: ·Kmentioning

confidence: 99%

High thermal conductivity in soft elastomers with elongated liquid metal inclusions

Bartlett

Kazem

Powell‐Palm

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

Self Cite

478

429

View full text Add to dashboard Cite

show abstract

“…In recent years, enormous attention and research enthusiasm have been devoted to high dielectric (high-k) materials for their wide applications in actuators [1,2], antennas [3], capacitors [4][5][6][7], wave-transparent (or absorbing) devices [8][9][10][11][12][13], and other electronic devices [14][15][16][17][18][19][20][21][22]. Most conventional highk materials are ceramic or ceramic composites, but their applications are seriously restricted by their intrinsic frangibility, high density, poor plasticity, and low breakdown strength.…”

Section: Introductionmentioning

confidence: 99%

“…However, the dielectric permittivities of polymer dielectrics are usually very low (below 10 @1 kHz), which greatly hindered their wide applications. Toward this end, two strategies have been developed to improve the dielectric constants of polymer composites: (1) ceramic-polymer composites composed of high-k ceramic fillers (e.g., BaTiO 3 [23][24][25][26][27], TiO 2 [28,29], SrTiO 3 [30]) dispersed in polymer matrix and (2) conductor-polymer composites consisting of conductors (e.g., metals, [31,32], graphite [33,34], carbon nanotube [35][36][37], graphene [38,39], carbon black [40], and conductive polymer [41,42]) dispersed in polymer matrix. For ceramic-polymer composites, the enhancement of permittivity is limited (below 50 @10 kHz) even when the ceramic loading excesses 50 vol%, leading to deteriorated mechanical properties, high loss, and low breakdown strength [43].…”

Section: Introductionmentioning

confidence: 99%

Improved dielectric permittivity and retained low loss in layer-structured films via controlling interfaces

Mao

Shi

Wang

et al. 2018

Adv Compos Hybrid Mater

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The search for high-performance dielectric materials has long been driven by the urgent needs for various modern electronics. However, enhanced permittivity is always accompanied by elevated loss, which seriously hinders the development and applications of dielectric materials. Herein, negative-k layers were introduced into layer-structured films, forming a new class of multilayer composites consisting of alternately stacked positive-k and negative-k layers. Compared with traditional multilayer composites without negative-k layers, the layered composites containing extra positive-k/negative-k interfaces exhibit superior ability in balancing the contradict parameters: permittivity and loss, yielding substantially enhanced permittivity without sacrificing the low loss. It is indicated that the permittivity was enhanced by the charge accumulations and reinforced polarizations on the interfaces between positive-k and negative-k layers. Meanwhile, the loss induced by the leakage current was suppressed by the blocked transport of carriers between adjacent layers. The trilayered 60-3.5-60 composite exhibits an enhanced dielectric constant (ε′ ≈ 33 @10 kHz) and retained low loss (tanδ ≈ 0.12 @10 kHz) compared with the single-layer BT/PVA composite containing 60 wt% BT fillers (ε′ ≈ 9.5 @10 kHz, tanδ ≈ 0.075 @10 kHz). This research offers an effective way to design and fabricate novel high-performance dielectric materials.

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“…EGaIn is a similar eutectic composition of 75.5%wt of gallium and 24.5%wt of indium (Dickey et al, 2008). Demonstrating superior performances in various aspects, gallium-based liquid metals have been explored for many novel applications, such as microfluidics devices (Khoshmanesh et al, 2017), stretchable electronics (Wang et al, 2015c;Bartlett et al, 2016), reconfigurable devices (Wang et al, 2015b), electronics cooling (Ma and Liu, 2007), vacuum pumping (Tang et al, 2015a), and painted conductive electrodes in liquid droplet actuation (Eaker et al, 2017). However, there are also some challenges in working with these liquid metals.…”

mentioning

confidence: 99%

Gallium-Based Room-Temperature Liquid Metals: Actuation and Manipulation of Droplets and Flows

Majidi

Gritsenko

2017

Front. Mech. Eng.

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Gallium-based room-temperature liquid metals possess extremely valuable properties, such as low toxicity, low vapor pressure, and high thermal and electrical conductivity enabling them to become suitable substitutes for mercury and beyond in wide range of applications. When exposed to air, a native oxide layer forms on the surface of gallium-based liquid metals which mechanically stabilizes the liquid. By removing or reconstructing the oxide skin, shape and state of liquid metal droplets and flows can be manipulated/actuated desirably. This can occur manually or in the presence/absence of a magnetic/electric field. These methods lead to numerous useful applications such as soft electronics, reconfigurable devices, and soft robots. In this mini-review, we summarize the most recent progresses achieved on liquid metal droplet generation and actuation of gallium-based liquid metals with/without an external force.

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Stretchable, High‐k Dielectric Elastomers through Liquid‐Metal Inclusions

Cited by 311 publications

References 29 publications

High thermal conductivity in soft elastomers with elongated liquid metal inclusions

High thermal conductivity in soft elastomers with elongated liquid metal inclusions

Improved dielectric permittivity and retained low loss in layer-structured films via controlling interfaces

Gallium-Based Room-Temperature Liquid Metals: Actuation and Manipulation of Droplets and Flows

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