Magnetic manipulation of liquid metals for soft robotics

Abstract

Soft robots harness compliant materials and bio-inspired architectures to achieve safe, adaptive, and versatile functions in dynamic environments, enabling applications in minimally invasive surgery, wearable assistive devices, and confined-space exploration. Gallium-based liquid metals with metallic conductivity and liquid deformability constitute a transformative material platform for creating soft robots with enhanced performance and diverse manipulation strategies. Among them, magnetic manipulation is particularly attractive because it enables remote, non-contact, and energy-efficient control with high spatial precision. In this review, we summarize existing strategies for the preparation, integration, and patterning of magnetic liquid metals. We then illustrate the mechanisms of magnetic manipulation, including magnet and Lorentz force manipulation, and discuss the potential of multi-field manipulation. Furthermore, we systematically categorize the practical applications of magnetically actuated liquid metals in soft robotics into four types: droplet, slurry, particle, and composite, based on their composition and morphology. Finally, we highlight the key challenges in this field and provide perspectives on future research directions. This review aims to establish a systematic framework for understanding and advancing magnetically manipulated liquid metals in soft robotics, offering fundamental insights to stimulate interdisciplinary research and accelerate technological breakthroughs in this emerging field.

Keywords

Liquid metals / magnetic manipulation / soft robotics

References

[1] Kim Y.Magnetic Soft Materials and Robots.Chem Rev2022;122:5317-64 PMCID:PMC9211764

[2] Zhang S,Jiang Q,Wu Z.Fabrication and functionality integration technologies for small-scale soft robots.Adv Mater2022;34:e2200671

[3] Hegde C,Tan JMR,Chen X.Sensing in soft robotics.ACS Nano2023;17:15277-307 PMCID:PMC10448757

[4] Tan YJ,Laschi C.Artificial muscles for underwater soft robots: materials and their interactions.Annu Rev Condens Matter Phys2024;15:45-61

[5] Kulkarni M,Golecki T,Golecki H.Soft robots built for extreme environments.Soft Sci2025;5:12

[6] Wu M,Wu J.Octopus-inspired underwater soft robotic gripper with crawling and swimming capabilities.Research2024;7:0456 PMCID:PMC11350063

[7] Xie Z,Liu J.Octopus-inspired sensorized soft arm for environmental interaction.Sci Robot2023;8:eadh7852

[8] Yue T,Tang K.Embodying soft robots with octopus-inspired hierarchical suction intelligence.Sci Robot2025;10:eadr4264

[9] Zhu M,Dinulescu SI,Hawkes EW.Soft, wearable robotics and haptics: technologies, trends, and emerging applications.Proc IEEE2022;110:246-72

[10] Yin S,Song Y.Wearable and implantable soft robots.Chem Rev2024;124:11585-636 PMCID:PMC12140402

[11] Bliah O,Tan JMR.Fabrication of soft robotics by additive manufacturing: from materials to applications.Chem Rev2025;125:7275-320 PMCID:PMC12395417

[12] Ren L,Du Y,Dou SX.Liquid metals and their hybrids as stimulus-responsive smart materials.Mater Today2020;34:92-114

[13] Li N,Li Y.Bioinspired liquid metal based soft humanoid robots.Adv Mater2024;36:e2404330

[14] He Y,Dickey MD.Controllable flow and manipulation of liquid metals.Adv Funct Materials2024;34:2309614

[15] Qi J,Jiang Y.Liquid metal-polymer conductor-based conformal cyborg devices.Chem Rev2024;124:2081-137

[16] Li J,Liu J.Biosimilar liquid-metal living matter.Matter2024;7:2033-65

[17] Wang H,Yuan B,Sun X.Liquid metal transformable machines.Acc Mater Res2021;2:1227-38

[18] Chen G,Chen Y.A stretchable liquid metal switch for interactive and autonomous soft machines.Int J Extrem Manuf2026;8:015510

[19] Li G,Liu S.Three-dimensional flexible electronics using solidified liquid metal with regulated plasticity.Nat Electron2023;6:154-63

[20] Wan C,Li X,Guo R.Interfacial adhesion effects of liquid metal printed electronics on general substrates: mechanisms and applications.InfoMat2025;7:e70029

[21] Li G,Xu Z,Tang S.Recent advancements in liquid metal enabled flexible and wearable biosensors.Soft Sci2023;3:37

[22] Wang H,Chen S,Dickey MD.Liquid metal composites with enhanced thermal conductivity and stability using molecular thermal linker.Adv Mater2021;33:e2103104

[23] Yao Y,Liu J.Liquid metal phase change materials for thermal management of electronics.Adv Phys X2024;9:2324910

[24] Ma J,Vong MH,Awartani OM.Shaping a soft future: patterning liquid metals.Adv Mater2023;35:e2205196

[25] Zhu J,Tong Y.Recent progress in multifunctional, reconfigurable, integrated liquid metal-based stretchable sensors and standalone systems.Prog Mater Sci2024;142:101228 PMCID:PMC11090487

[26] Kim H,Seo Y,Park C.Stimuli‐responsive liquid metal hybrids for human‐interactive electronics.Adv Funct Mater2024;34:2308703

[27] Chen S,Zhao R,Liu J.Liquid metal composites.Matter2020;2:1446-80

[28] Chen S,Liu T.Liquid metal smart materials toward soft robotics.Adv Intell Syst2023;5:2200375

[29] Liang F.Functional liquid metal polymeric composites: fundamentals and applications in soft wearable electronics.Adv Funct Mater2024;34:2400284

[30] Lee S,Atar N.Connecting the dots: sintering of liquid metal particles for soft and stretchable conductors.Chem Rev2025;125:3551-85

[31] Wang L,Zhang L,Fu L.Emerging liquid metal biomaterials: from design to application.Adv Mater2022;34:e2201956

[32] Chen S,Sun X,Li L.Toxicity and biocompatibility of liquid metals.Adv Healthc Mater2023;12:e2201924

[33] Handschuh-Wang S,Gancarz T.The liquid metal age: a transition from Hg to Ga.Adv Mater2024;36:e2408466

[34] Wang D,Liu Y.Liquid metal gallium pharmaceuticals.Theranostics2025;15:8795-821 PMCID:PMC12439269

[35] Khan MR,Bowden EF.Giant and switchable surface activity of liquid metal via surface oxidation.Proc Natl Acad Sci U S A2014;111:14047-51 PMCID:PMC4191764

[36] Eaker CB,O’Regan JD,Daniels KE.Oxidation-mediated fingering in liquid metals.Phys Rev Lett2017;119:174502

[37] Yun FF,He Y.Voltage-induced penetration effect in liquid metals at room temperature.Natl Sci Rev2020;7:366-72 PMCID:PMC8288959

[38] He Y,Dickey MD.Liquid-metal transfer from an anode to a cathode without short circuiting.Nat Chem Eng2024;1:293-300

[39] Handschuh-Wang S,Zhu L,Zhou X.Electric actuation of liquid metal droplets in acidified aqueous electrolyte.Langmuir2019;35:372-81

[40] Babatain W,Harraz DM.Programmable continuous electrowetting of liquid metal for reconfigurable electronics.Adv Mater2026;38:e06383

[41] Kim D,Chung SK.Magnetic liquid metals: a review.Adv Funct Mater2024;34:2311153

[42] Shen Y,Li T,Ma X.Magnetically responsive gallium-based liquid metal: preparation, property and application.ACS Nano2024;18:20027-54

[43] Xiang W,Wang H.Liquid-metal-based magnetic fluids.Nat Rev Mater2024;9:433-49

[44] Ito R,Fujita T.Mr fluid of liquid gallium dispersing magnetic particles.Int J Mod Phys B2005;19:1430-6

[45] Chen J,Wang Q.Programming ferromagnetic soft materials for miniature soft robots: design, fabrication, and applications.J Mater Sci Technol2025;219:271-87

[46] Ma B,Chi J,Zhao C.A versatile approach for direct patterning of liquid metal using magnetic field.Adv Funct Mater2019;29:1901370

[47] Hu W,Mastrangeli M.Small-scale soft-bodied robot with multimodal locomotion.Nature2018;554:81-5

[48] Yang Z,Lee JX.Magnetic miniature soft robot with reprogrammable drug-dispensing functionalities: toward advanced targeted combination therapy.Adv Mater2024;36:e2408750

[49] Wang X,Ge J.Untethered and ultrafast soft-bodied robots.Commun Mater2020;1:67

[50] Li X,Lu Y.Programmable digital liquid metal droplets in reconfigurable magnetic fields.ACS Appl Mater Interfaces2020;12:37670-9

[51] Jeong J,Chung SK.Electromagnetic three dimensional liquid metal manipulation.Lab Chip2019;19:3261-7

[52] Chang H,Sun Z.Direct writing and repairable paper flexible electronics using nickel-liquid metal ink.Adv Materials Inter2018;5:1800571

[53] Varga M,Ma S,Tröster G.On-skin liquid metal inertial sensor.Lab Chip2017;17:3272-8

[54] Shen Y,Fu M.Reactive wetting enabled anchoring of non-wettable iron oxide in liquid metal for miniature soft robot.Nat Commun2023;14:6276 PMCID:PMC10560245

[55] He Y,Kalantar-Zadeh K,Wang X.Noncontact rotation, levitation, and acceleration of flowing liquid metal wires.Proc Natl Acad Sci U S A2022;119:e2117535119 PMCID:PMC8833150

[56] Wang D,Wang W.Shape-transformable, fusible rodlike swimming liquid metal nanomachine.ACS Nano2018;12:10212-20

[57] Maurin V,Ze Q,Wang J.Liquid crystal elastomer-liquid metal composite: ultrafast, untethered, and programmable actuation by induction heating.Adv Mater2024;36:e2302765

[58] Elbourne A,Atkin P.Antibacterial liquid metals: biofilm treatment via magnetic activation.ACS Nano2020;14:802-17

[59] Wang H,Li H.A liquid gripper based on phase transitional metallic ferrofluid.Adv Funct Mater2021;31:2100274

[60] Kim S,Kim JY.Magnetic manipulation of locomotive liquid electrodes for wireless active cardiac monitoring.ACS Appl Mater Interfaces2023;15:28954-63 PMCID:PMC10288434

[61] Cao L,Xia Z.Ferromagnetic liquid metal putty-like material with transformed shape and reconfigurable polarity.Adv Mater2020;32:e2000827

[62] Jeon J,Chung SK.Magnetic liquid metal marble: characterization of lyophobicity and magnetic manipulation for switching applications.J Microelectromech Syst2016;25:1050-7

[63] Chen H,Qiao K.Thermomagnetic liquid metal switches with fast bidirectional response.Nat Commun2025;16:2634 PMCID:PMC11914592

[64] Chang H,Guo R.Recoverable liquid metal paste with reversible rheological characteristic for electronics printing.ACS Appl Mater Interfaces2020;12:14125-35

[65] Wang D,Rao W.Precise regulation of Ga-based liquid metal oxidation.Acc Mater Res2021;2:1093-103

[66] Feng D,Xu C.Renewable electrode array based on transformable metal for scaling up DNA synthesis and manipulation.Adv Funct Mater2026;36:e13703

[67] Jung W,Kwon K.Giant decrease in interfacial energy of liquid metals by native oxides.Adv Mater2024;36:e2406783 PMCID:PMC11602690

[68] Wu D,Tian X.A universal mechanochemistry allows on-demand synthesis of stable and processable liquid metal composites.Small Methods2022;6:e2200246

[69] Xing W,Wang H.Construction of 3D conductive network in liquid gallium with enhanced thermal and electrical performance.Adv Mater Technol2022;7:2100970

[70] Lin Y,Dickey MD.Attributes, fabrication, and applications of gallium-based liquid metal particles.Adv Sci2020;7:2000192 PMCID:PMC7312306

[71] Yang C,Qin J,Zhao X.Metal-based magnetic functional fluids with amorphous particles.RSC Adv2014;4:59541-7

[72] Kim D.Magnetic-field-induced liquid metal droplet manipulation.J Korean Phys Soc2015;66:282-6

[73] Chen R,Song R.Magnetically controllable liquid metal marbles.Adv Mater Interfaces2019;6:1901057

[74] Lu Y,Sun F.Mussel-inspired multifunctional integrated liquid metal-based magnetic suspensions with rheological, magnetic, electrical, and thermal reinforcement.ACS Appl Mater Interfaces2021;13:5256-65

[75] Tang J,Li J,Liu J.Liquid metal phagocytosis: intermetallic wetting induced particle internalization.Adv Sci2017;4:1700024

[76] Lu Y,Dong H.Dynamic leakage‐free liquid metals.Adv Funct Mater2023;33:2210961

[77] Carle F,Casara J,Brown E.Development of magnetic liquid metal suspensions for magnetohydrodynamics.Phys Rev Fluids2017;2:013301

[78] Zhu H,Zhang M,Hu G.Fully solution processed liquid metal features as highly conductive and ultrastretchable conductors.npj Flex Electron2021;5:123

[79] Chen G,Zhang J,Liu H.Reprogrammable magnetic soft robots based on low melting alloys.Adv Intell Syst2023;5:2300173

[80] Zhao R,Yao H.Liquid-metal magnetic soft robot with reprogrammable magnetization and stiffness.IEEE Robot Autom Lett2022;7:4535-41

[81] Gao X,Xu C.Water-based continuous fabrication of highly elastic electromagnetic fibers.ACS Nano2024;18:17913-23

[82] Mao G,Karami-Mosammam M.Soft electromagnetic actuators.Sci Adv2020;6:eabc0251 PMCID:PMC7319732

[83] Ma J,Im S.Injection molding of liquid metal by harnessing nonstick molds.ACS Appl Mater Interfaces2024;16:10931-41

[84] Lin Y,Khan MR,Genzer J.Vacuum filling of complex microchannels with liquid metal.Lab Chip2017;17:3043-50

[85] Kohls N,Ruddy BP.Design of a xenia coral robot using a high-stroke compliant linear electromagnetic actuator.ASME Letters in Dynamic Systems and Control2021;1:031011

[86] Wu Q,Wu Z.Suspension printing of liquid metal in yield-stress fluid for resilient 3D constructs with electromagnetic functions.npj Flex Electron2022;6:184

[87] Zhang Y,Hu Y.Reconfigurable magnetic liquid metal robot for high-performance droplet manipulation.Nano Lett2022;22:2923-33

[88] Kim H,Oh JW.Shape‐deformable and locomotive MXene (Ti₃C₂T_x)‐encapsulated magnetic liquid metal for 3D‐motion‐adaptive synapses.Adv Funct Mater2023;33:2210385

[89] Hu L,Wang X,Guo J.Magnetic liquid metals manipulated in the three-dimensional free space.ACS Appl Mater Interfaces2019;11:8685-92

[90] Ren L,Casillas-Garcia G.A liquid-metal-based magnetoactive slurry for stimuli-responsive mechanically adaptive electrodes.Adv Mater2018;30:e1802595

[91] Kadau H,Wenzel M.Observing the rosensweig instability of a quantum ferrofluid.Nature2016;530:194-7

[92] Torres-Díaz I.Recent progress in ferrofluids research: novel applications of magnetically controllable and tunable fluids.Soft Matter2014;10:8584-602

[93] Guo R,Yuan B,Liu J.Magnetic liquid metal (Fe-EGaIn) based multifunctional electronics for remote self-healing materials, degradable electronics, and thermal transfer printing.Adv Sci2019;6:1901478 PMCID:PMC6794621

[94] Zhang J,Wei Z,Sitti M.Liquid metal-elastomer composites with dual-energy transmission mode for multifunctional miniature untethered magnetic robots.Adv Sci2022;9:e2203730 PMCID:PMC9631051

[95] Yu Y.Alternating-magnetic-field-mediated wireless manipulations of a liquid metal for therapeutic bioengineering.iScience2018;3:134-48 PMCID:PMC6137341

[96] Chen BC,Kao LJ,Tsai YH.Hysteresis loss-induced temperature in ferromagnetic nanoparticle.IEEE Trans Magn2014;50:1-4

[97] Tan S,Yuan B.Magnetic trap effect to restrict motion of self-powered tiny liquid metal motors.Applied Physics Letters2015;107:071904

[98] Ni X,Kim JT.Soft shape-programmable surfaces by fast electromagnetic actuation of liquid metal networks.Nat Commun2022;13:5576 PMCID:PMC9508113

[99] Jin SW,Hong SY.Stretchable loudspeaker using liquid metal microchannel.Sci Rep2015;5:11695 PMCID:PMC4504143

[100] Thess A,Kolesnikov Y.Lorentz force velocimetry.Phys Rev Lett2006;96:164501

[101] Yang X,Ze Q.Electromagnetic-stimulated untethered amphibious soft robot with multimodal locomotion.Mater Today2025;87:11-9

[102] Wang D,Si T,Guo B.Near-infrared light propelled motion of needlelike liquid metal nanoswimmers.Colloids Surf A Physicochem Eng Aspects2021;611:125865

[103] Zhao X,Zhou Y.Liquid metal droplet dynamics.Droplet2024;3:e104

[104] He X,Wu J,Gong X.Hard-magnetic liquid metal droplets with excellent magnetic field dependent mobility and elasticity.J Mater Sci Technol2021;92:60-8

[105] Firouznia S,Philamore H,Garrad M.Shapeshifting liquid metal droplets for soft fluidic machines.Adv Mater2025;Epub ahead of print:

[106] Xu Y,Chen H,Wu Z.A soft reconfigurable circulator enabled by magnetic liquid metal droplet for multifunctional control of soft robots.Adv Sci2023;10:e2300935 PMCID:PMC10427373

[107] Li P,Ding C.Magnetointeractive Cr₂Te₃-coated liquid metal droplets for flexible memory arrays and wearable sensors.Adv Mater2025;37:e2414519

[108] Wang Q,Zhang Y.Magnetoactive liquid-solid phase transitional matter.Matter2023;6:855-72

[109] Cao Y,Gao J.Magnetic and injectable Fe-doped liquid metals for controlled movement and photothermal/electromagnetic therapy.J Mater Chem B2024;12:2313-23

[110] Jiang J,Chen C,Song J.Tunable and reversible adhesive of liquid metal ferrofluid pillars for magnetically actuated noncontact transfer printing.Adv Mater2024;36:e2314004

[111] Guo R,Chang H.Ni‐GaIn amalgams enabled rapid and customizable fabrication of wearable and wireless healthcare electronics.Adv Eng Mater2018;20:1800054

[112] Wu Y,Peng Z.A novel strategy for preparing stretchable and reliable biphasic liquid metal.Adv Funct Mater2019;29:1903840

[113] Li S,Lv Y.Magnetic liquid metal scaffold with dynamically tunable stiffness for bone tissue engineering.Biomater Adv2022;139:212975

[114] Sun X,Duan M.Flexible skin patch enabled tumor hybrid thermophysical therapy and adaptive antitumor immune response.Adv Healthc Mater2023;12:e2202872

[115] Hwang H,Baek J,Kim Y.Engineering liquid metal particles: design rules for sonication-based methods.Nano Lett2025;25:9881-90 PMCID:PMC12203638

[116] Wang B,Lin J,Zhou X.A swarm of liquid metal microdroplets for recyclable catalysis with high spatial-temporal precision.Appl Mater Today2023;34:101903

[117] Wu X,Ren L,Pumera M.Reconfigurable magnetic liquid metal microrobots: a regenerable solution for the capture and removal of micro/nanoplastics.Adv Funct Mater2024;34:2410167

[118] Liu Z,Tan X.Transformable magnetic liquid-metal nanoplatform for intracellular drug delivery and MR imaging-guided microwave thermochemotherapy.ACS Appl Mater Interfaces2024;16:9826-38

[119] Wang D,Guo R,Niu M.Magnetic liquid metal loaded nano-in-micro spheres as fully flexible theranostic agents for SMART embolization.Nanoscale2021;13:8817-36

[120] Liu Z,Huang Y.Microwave absorption-based magnetic liquid metal nano-missiles for thermodynamic/immunological cascade hepatoma therapy.Chem Eng J2023;471:144688

[121] Wu X,Tong Y.Self-adaptive magnetic liquid metal microrobots capable of crossing biological barriers and wireless neuromodulation.ACS Nano2024;18:29558-71

[122] Zhang M,Sun Y.A magnetically and thermally controlled liquid metal variable stiffness material.Adv Eng Mater2023;25:2201296

[123] Mao G,Danninger D.Ultrafast small-scale soft electromagnetic robots.Nat Commun2022;13:4456 PMCID:PMC9363453

[124] Li W,Yi Z.Self-vectoring electromagnetic soft robots with high operational dimensionality.Nat Commun2023;14:182 PMCID:PMC9837125

[125] Li N,Li Y.Transformable 3D curved high-density liquid metal coils - an integrated unit for general soft actuation, sensing and communication.Nat Commun2024;15:7679 PMCID:PMC11377734

[126] Zhou X,Jin H.Variable stiffness wires based on magnetorheological liquid metals.Int J Smart Nano Mater2022;13:232-43

[127] Chen Y,Li R.High-performance liquid metal electromagnetic actuator fabricated by femtosecond laser.Int J Extrem Manuf2024;6:025503

[128] Shin G,Jeon B,Song S.Soft electromagnetic artificial muscles using high‐density liquid‐metal solenoid coils and bistable stretchable magnetic housings.Adv Funct Mater2024;34:2302895

[129] Shen Y,Zhou E.Tough hydrogel-coated containment capsule of magnetic liquid metal for remote gastrointestinal operation.Natl Sci Rev2025;12:nwaf042 PMCID:PMC11892562

[130] Kim E,Hong YM.Magnetically reshapable 3D multi-electrode arrays of liquid metals for electrophysiological analysis of brain organoids.Nat Commun2025;16:2011 PMCID:PMC11868496

[131] Zhao B,Lv H.Self-healing liquid metal magnetic hydrogels for smart feedback sensors and high-performance electromagnetic shielding.Nanomicro Lett2023;15:79 PMCID:PMC10066054

[132] Zhu G,Tan J.Fabrication of core-shell liquid metal@silica nanoparticles for enhanced mechanical, dielectric and thermal properties of silicone rubber.CrystEngComm2023;25:3299-307

[133] Hallfors N,Dickey MD.Integration of pre-aligned liquid metal electrodes for neural stimulation within a user-friendly microfluidic platform.Lab Chip2013;13:522-6 PMCID:PMC4394010

[134] Wang X,Zhang J.Printed conformable liquid metal e‐skin‐enabled spatiotemporally controlled bioelectromagnetics for wireless multisite tumor therapy.Adv Funct Mater2019;29:1907063

[135] Tian H,Zhang W.Recent advances for core-shell gallium-based liquid metal particles: properties, fabrication, modification, and applications.Nanoscale2025;17:11934-59

[136] Xu H,Xi Y,Liu J.Liquid metal biomaterials: translational medicines, challenges and perspectives.Natl Sci Rev2024;11:nwad302 PMCID:PMC10776368

[137] Liu Y,Wang H.Synthesis and application of core-shell liquid metal particles: a perspective of surface engineering.Mater Horiz2021;8:56-77

[138] Pham DQ,Berndt CC.Antibacterial longevity of a novel gallium liquid metal/hydroxyapatite composite coating fabricated by plasma spray.ACS Appl Mater Interfaces2022;14:18974-88