Reconfigurable ferromagnetic liquid droplets

Liu, Xubo; Kent, Noah; Ceballos, Alejandro; Streubel, Robert; Jiang, Yufeng; Chai, Yi; Kim, Paul Y.; Forth, Joe; Hellman, F.; Shi, Shaowei; Wang, Dong; Helms, Brett A.; Ashby, Paul D.; Fischer, Peter; Russell, Thomas P.

doi:10.1126/science.aaw8719

Cited by 314 publications

(173 citation statements)

References 19 publications

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“…In refs. [17–20], the movements of droplets in various conditions and with different geometrical configurations, such as a round petri dish and circular narrow channels, were observed and recorded. Moreover, in the multiple droplets system, the separation and coalescence of the droplets can be realized, which makes their behavior more complicated and charming.…”

Section: Introductionmentioning

confidence: 99%

Ferrofluid Droplets as Liquid Microrobots with Multiple Deformabilities

Fan

Sun

et al. 2020

Adv Funct Materials

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Developing microrobots with multiple deformabilities has become extremely challenging due to the lack of materials that are soft enough at the microscale level and the inability to be reconfigured after fabrication. In this study, it is aimed to prove that liquid microrobots composed of ferrofluid droplets are inherently deformable and they can be controlled, individually or in aggregate, with multiple programmable deformabilities. For example, the liquid‐microrobot monomer (LRM) can pass through narrow channels via elongation and achieve scaling via splitting and coalescence. LRMs can also reassemble into various kinds of functional liquid‐robot aggregates, such as microsticks, micropies, microtrains, microkayaks, and microrollingpins. Thus, they can respond to multi‐terrain surfaces or perform various complex tasks. Moreover, the authors' physics‐based theoretical model demonstrates dynamic self‐assembly and group behavior of a multiple LRM system, which is conducive to investigating the mechanisms behind it. These ferrofluid droplet robots provide novel solutions for some potential applications, such as untethered micromanipulation and targeted cargo delivery.

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Section: Introductionmentioning

confidence: 99%

Ferrofluid Droplets as Liquid Microrobots with Multiple Deformabilities

Fan

Sun

et al. 2020

Adv Funct Materials

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“…However, PZN‐PT single crystals with a big size is not easily achievable compared with the process for PMN‐PT because the composition is not stable at elevated temperatures and is easily decomposed from perovskite to the pyrochlore phase . Recently, Li et al achieved a superhigh piezoelectric coefficient d 33 of 3400–4100 pC N −1 with an Sm‐doped PMN‐PT single crystal, but the corresponding T c and T rt values are only 65 and 60 °C, respectively, which limits its upper service temperature.…”

Section: Piezoelectric Materials For Actuatorsmentioning

confidence: 99%

Piezoelectric Actuators and Motors: Materials, Designs, and Applications

Gao

Yang

et al. 2019

Adv Materials Technologies

317

126

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especially irreplaceable role in the area of precision actuations, such as in lens driving in optical assemblies and optical communication, micro/nanopositioning in semiconductor and microelectromechanical system (MEMS) manufacturing, nanoscanning probes in scanning electron microscopy, etc. [1,2] Due to the huge market demand for piezoelectric actuators, the progress of piezoelectric materials and devices is new every year. New piezoelectric material compositions, novel fabrication processes and full assessments of materials are widely studied to improve the material properties or make devices more suitable for actuation applications. Pb(Zr,Ti)O 3 (PZT)-based ceramics are still dominant in the market because of their high piezoelectric properties, low cost, and stable thermal performance. Although single crystals' piezoelectric and electromechanical coupling coefficients show great advances compared with ceramics, actuation applications are limited to only some special cases due to high cost of single crystals. [3] Lead-free ceramics have also experienced fast development, and some compositions have been found to exhibit large strains, but they also result in large energy losses under high electric fields. This type of ceramic may have potential for use in nonresonant actuator applications. Additionally, various actuation configurations operating via different working modes or mechanisms have been developed.In this review, we first introduce materials used for the corresponding actuators and motors, and then, recent developments in the area of actuators including nonresonant multilayer ceramic actuators, step motors and inertial motors, and resonant ultrasonic motors, such as linear motors, rotary motors, multi-DOF motors, and MEMS actuators, are discussed. Actuation performance parameters such as the stroke length, resolution, loading force, velocity, lifetime, and power efficiency are the main concerns. We try to clarify and compare differences between devices. Finally, the challenges and outlook for the piezoelectric actuators are discussed. Piezoelectric Materials for ActuatorsPiezoelectricity in materials can be attributed to an asymmetric center of the crystalline structure or molecular chain, which Piezoelectric actuators are unique driving force-generation devices, which can transfer input electric energy into force, displacement, or movement outputs efficiently and precisely via piezoelectric effect-based electromechanical coupling instead of electromagnetic induction. In comparison with traditional electromagnetic actuators, the most important features of the piezoelectric actuators are their compact size, flexible design, and ability to provide nanometer or sub-micrometer positioning. Here, recent progress in nonresonance piezoelectric actuators including multilayer ceramic actuators, step motors, inertial motors, and resonance ultrasonic motors, such as linear motors, rotary motors, multidegree of freedom motors, and microelectromechanical system actuators, is comprehensively presented. The working p...

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“…Recently, a reversible paramagnetic‐to‐ferromagnetic transformation of ferrofluid droplets by the jamming of a monolayer of magnetic nanoparticles assembled at the water–oil interface was developed. [ 8 ] However, this well‐designed framework is applicable only within the liquid system. The elastic matrix‐based AMC could achieve a limited reconfigurable shape, while the dynamically programmed and reversible magnetic reconfiguration meets a huge challenge.…”

Section: Figurementioning

confidence: 99%

Ferromagnetic Liquid Metal Putty‐Like Material with Transformed Shape and Reconfigurable Polarity

Cao

Xia

et al. 2020

Advanced Materials

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by both the magnetic filler and the matrix. The liquid-like ferrofluids with transformed shape easily lose magnetization once the applied magnetic field is removed, and the solid ferromagnetic materials are hard to be reconfigured as needed.Recently, a reversible paramagnetic-toferromagnetic transformation of ferrofluid droplets by the jamming of a monolayer of magnetic nanoparticles assembled at the water-oil interface was developed. [8] However, this well-designed framework is applicable only within the liquid system. The elastic matrix-based AMC could achieve a limited reconfigurable shape, while the dynamically programmed and reversible magnetic reconfiguration meets a huge challenge. [9] In addition, there is an inevitable mismatch between the electrical and ferromagnetic performances for most AMC materials due to the insulative matrix. It is naturally desirable to design a reconfigurable ferromagnetic material with high electrical conductivity and transformed shape, attracting massive attention due to the promising applications in many fields such as flexible electronics and soft robotics.Here, we present a novel reconfigurable ferromagnetic liquid metal putty-like material (FM-LMP) with high electrical conductivity, prepared by homogenously mixing the room temperature LM of EGaIn (the melting point of 15.7 °C) and ferromagnetic neodymium-iron-boron (NdFeB) microparticles, as illustrated schematically in Figure 1a. The NdFeB microparticles dispersed in the LM matrix were then magnetically saturated through a strong impulse of the magnetic field. It is surprising to find that the magnetization could turn the liquid-like suspension into the solid-like putty-like material. The FM-LMP is thus easily remodeled like modelling clay to various magnet shapes. The macroscopic magnetic performance of the FM-LMP stems from the magnetic orientation alignment of the magnetized NdFeB microparticles immersed in the LM matrix, as illustrated in Figure 1b. The magnetic polarity alignment of magnetized microparticles with high mobility when suspended in the LM matrix could be reversibly disordered and rearranged to enable FM-LMP exhibit macro scopical demagnetization and magnetization. The magnetic LM [10] has been recently proposed through mixing soft magnetic materials (such as pure iron or It is remarkably desirable and challenging to design reconfigurable ferromagnetic materials with high electrical conductivity. This has attracted great attention due to promising applications in many fields such as emerging flexible electronics and soft robotics. However, the shape and magnetic polarity of existing ferromagnetic materials with low conductivity are both hard to be reconfigured, and the magnetization of insulative ferrofluids is easily lost once the external magnetic field is removed. A novel reconfigurable ferromagnetic liquid metal (LM) puttylike material (FM-LMP) with high electrical conductivity and transformed shape, which is prepared through homogenously mixing neodymiumiron-boron microparticles into the gallium-base...

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Reconfigurable ferromagnetic liquid droplets

Cited by 314 publications

References 19 publications

Ferrofluid Droplets as Liquid Microrobots with Multiple Deformabilities

Ferrofluid Droplets as Liquid Microrobots with Multiple Deformabilities

Piezoelectric Actuators and Motors: Materials, Designs, and Applications

Ferromagnetic Liquid Metal Putty‐Like Material with Transformed Shape and Reconfigurable Polarity

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