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They enable motion and determine strength and dexterity. The fiber form factor makes skeletal muscles modular, scalable, and densely integrated (50% of human body weight). In contrast, servo motors that drive today\u2019s robots lack the flexibility and modularity of muscle fibers, limiting integration and dexterity. Here, we report electrofluidic fiber muscles, soft artificial muscles for robotic applications with power density comparable to skeletal muscles (50 watts per kilogram), contraction strains of 20%, and response time of 0.3 second. These 2-millimeter-thick muscles comprise antagonistic fluidic actuators driven by electrohydrodynamic fiber pumps in a closed circuit. They require no external liquid reservoir and are electrically driven, untethered, and silent. We demonstrated that performance is increased by pre-pressurizing the muscles at an optimal bias pressure. Applying bias pressure allowed the antagonist actuator to act as a reservoir for the agonist, enabled 200% higher operating voltages by preventing cavitation, and leveraged the nonlinear pressure-stroke response of the actuators, increasing strain threefold at a given pump pressure. We characterized and modeled their dynamics, identifying optimal bias pressures. Electrofluidic muscles scale by simply bundling fibers. By selecting the ratio between pumps and actuators, we programmed their performance for different robotic tasks: a fast lever (180 millimeters per second) that launches objects in &lt;0.3 second; a strong bundle that lifts 4 kilograms (200 times its weight) with a 30-millimeter stroke; a woven muscle that bends a robot arm by 40\u00b0 and is compliant enough for a human handshake.<\/jats:p>","DOI":"10.1126\/scirobotics.ady6438","type":"journal-article","created":{"date-parts":[[2026,3,25]],"date-time":"2026-03-25T17:58:51Z","timestamp":1774461531000},"update-policy":"https:\/\/doi.org\/10.34133\/aaas_crossmark","source":"Crossref","is-referenced-by-count":3,"title":["Electrofluidic fiber muscles"],"prefix":"10.1126","volume":"11","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-5703-2973","authenticated-orcid":true,"given":"O. 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Suzumori S. Iikura H. Tanaka \u201cDevelopment of flexible microactuator and its applications to robotic mechanisms \u201d in Proceedings 1991 IEEE International Conference on Robotics and Automation (IEEE 1991) pp. 1622\u20131627.","DOI":"10.1109\/ROBOT.1991.131850"},{"key":"e_1_3_2_5_2","doi-asserted-by":"publisher","DOI":"10.1002\/anie.201006464"},{"key":"e_1_3_2_6_2","doi-asserted-by":"publisher","DOI":"10.1016\/j.robot.2020.103427"},{"key":"e_1_3_2_7_2","doi-asserted-by":"publisher","DOI":"10.1089\/soro.2015.0019"},{"key":"e_1_3_2_8_2","doi-asserted-by":"publisher","DOI":"10.1073\/pnas.1116564108"},{"key":"e_1_3_2_9_2","doi-asserted-by":"publisher","DOI":"10.1126\/scirobotics.aay2627"},{"key":"e_1_3_2_10_2","doi-asserted-by":"crossref","unstructured":"K. Suzumori S. Endo T. Kanda N. Kato H. Suzuki \u201cA bending pneumatic rubber actuator realizing soft-bodied manta swimming robot \u201d in IEEE International Conference on Robotics and Automation (ICRA) (IEEE 2007) pp. 4975\u20134980.","DOI":"10.1109\/ROBOT.2007.364246"},{"key":"e_1_3_2_11_2","doi-asserted-by":"publisher","DOI":"10.1038\/s41586-019-1313-1"},{"key":"e_1_3_2_12_2","doi-asserted-by":"publisher","DOI":"10.1038\/s41467-023-42882-3"},{"key":"e_1_3_2_13_2","doi-asserted-by":"publisher","DOI":"10.1089\/soro.2020.0064"},{"key":"e_1_3_2_14_2","doi-asserted-by":"publisher","DOI":"10.1126\/scirobotics.adi2377"},{"key":"e_1_3_2_15_2","doi-asserted-by":"crossref","unstructured":"M. Takeichi K. Suzumori G. Endo H. Nabae \u201cDevelopment of a 20-m-long Giacometti arm with balloon body based on kinematic model with air resistance \u201d in 2017 IEEE\/RSJ International Conference on Intelligent Robots and Systems (IROS) (IEEE 2017) pp. 2710\u20132716.","DOI":"10.1109\/IROS.2017.8206097"},{"key":"e_1_3_2_16_2","doi-asserted-by":"publisher","DOI":"10.1063\/1.4937735"},{"key":"e_1_3_2_17_2","doi-asserted-by":"publisher","DOI":"10.1002\/marc.201500576"},{"key":"e_1_3_2_18_2","doi-asserted-by":"publisher","DOI":"10.1073\/pnas.1815053116"},{"key":"e_1_3_2_19_2","doi-asserted-by":"publisher","DOI":"10.1089\/soro.2017.0062"},{"key":"e_1_3_2_20_2","doi-asserted-by":"publisher","DOI":"10.1126\/scirobotics.adp4256"},{"key":"e_1_3_2_21_2","doi-asserted-by":"publisher","DOI":"10.1126\/scirobotics.aau9795"},{"key":"e_1_3_2_22_2","doi-asserted-by":"publisher","DOI":"10.1126\/science.aao6139"},{"key":"e_1_3_2_23_2","doi-asserted-by":"publisher","DOI":"10.1002\/adma.202002564"},{"key":"e_1_3_2_24_2","doi-asserted-by":"publisher","DOI":"10.1126\/scirobotics.aaz5796"},{"key":"e_1_3_2_25_2","doi-asserted-by":"publisher","DOI":"10.1126\/scirobotics.aar3276"},{"key":"e_1_3_2_26_2","doi-asserted-by":"publisher","DOI":"10.1126\/scirobotics.adr0721"},{"key":"e_1_3_2_27_2","doi-asserted-by":"publisher","DOI":"10.1126\/scirobotics.abi8189"},{"key":"e_1_3_2_28_2","doi-asserted-by":"publisher","DOI":"10.1002\/adfm.202209080"},{"key":"e_1_3_2_29_2","doi-asserted-by":"publisher","DOI":"10.1002\/adfm.202314056"},{"key":"e_1_3_2_30_2","doi-asserted-by":"publisher","DOI":"10.1002\/adfm.202570101"},{"key":"e_1_3_2_31_2","doi-asserted-by":"publisher","DOI":"10.1002\/adfm.202111145"},{"key":"e_1_3_2_32_2","doi-asserted-by":"publisher","DOI":"10.1002\/adma.202208517"},{"key":"e_1_3_2_33_2","doi-asserted-by":"publisher","DOI":"10.1109\/TMECH.2022.3194975"},{"key":"e_1_3_2_34_2","doi-asserted-by":"publisher","DOI":"10.1002\/adfm.202415099"},{"key":"e_1_3_2_35_2","doi-asserted-by":"publisher","DOI":"10.1126\/sciadv.ads3058"},{"key":"e_1_3_2_36_2","doi-asserted-by":"publisher","DOI":"10.1002\/mame.202300252"},{"key":"e_1_3_2_37_2","doi-asserted-by":"publisher","DOI":"10.1002\/smll.201801883"},{"key":"e_1_3_2_38_2","doi-asserted-by":"publisher","DOI":"10.1126\/scirobotics.adl3546"},{"key":"e_1_3_2_39_2","doi-asserted-by":"publisher","DOI":"10.1126\/science.ade8654"},{"key":"e_1_3_2_40_2","doi-asserted-by":"publisher","DOI":"10.1016\/j.sna.2017.04.047"},{"key":"e_1_3_2_41_2","doi-asserted-by":"crossref","unstructured":"A. Kodaira H. Nabae T. Horiuchi K. Asaka G. Endo K. Suzumori \u201cAu\/Pt double-layer electrodes and expanding internal chamber for improving air-hose-free thin McKibben muscles \u201d in 2021 IEEE 4th International Conference on Soft Robotics (RoboSoft) (IEEE 2021) pp. 419\u2013426.","DOI":"10.1109\/RoboSoft51838.2021.9479222"},{"key":"e_1_3_2_42_2","doi-asserted-by":"publisher","DOI":"10.1007\/s42235-022-00225-w"},{"key":"e_1_3_2_43_2","doi-asserted-by":"publisher","DOI":"10.1007\/s42765-022-00254-4"},{"key":"e_1_3_2_44_2","doi-asserted-by":"publisher","DOI":"10.1109\/LRA.2023.3293316"},{"key":"e_1_3_2_45_2","unstructured":"3M Novec 7100 engineered fluid; https:\/\/multimedia.3m.com\/mws\/media\/199818O\/3m-novec-7100-engineered-fluid.pdf."},{"key":"e_1_3_2_46_2","doi-asserted-by":"publisher","DOI":"10.3390\/mi14020321"},{"key":"e_1_3_2_47_2","doi-asserted-by":"crossref","unstructured":"S. Wakimoto K. Suzumori J. 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Shea \u201cIncreasing the performance of EHD fiber pumps by scaling and by changing to a more sustainable working fluid \u201d presentation at the 2024 MRS Fall Meeting & Exhibit (Materials Research Society 2024); https:\/\/mrs.org\/meetings-events\/annual-meetings\/archive\/meeting\/presentations\/view\/2024-fall-meeting\/2024-fall-meeting-4151248."},{"key":"e_1_3_2_54_2","doi-asserted-by":"publisher","DOI":"10.1002\/adma.202502669"},{"key":"e_1_3_2_55_2","doi-asserted-by":"publisher","DOI":"10.1080\/15397730802405879"},{"key":"e_1_3_2_56_2","doi-asserted-by":"publisher","DOI":"10.3389\/frobt.2023.1109563"},{"key":"e_1_3_2_57_2","doi-asserted-by":"crossref","unstructured":"S. Yokota Y. Otsubo K. Edamura Electro-sensitive movable fluids methods of using the same and motors for the electro-sensitive movable fluids US Patent US6030544A (2000); https:\/\/patents.google.com\/patent\/US6030544A\/en.","DOI":"10.1016\/S1471-3918(00)80011-8"},{"key":"e_1_3_2_58_2","doi-asserted-by":"publisher","DOI":"10.1038\/s41598-024-55472-0"},{"key":"e_1_3_2_59_2","doi-asserted-by":"crossref","unstructured":"T. Morita T. Kurosawa K. Aoyama H. Kaimoto Y. Kuwajima S. Maeda Y. Kakehi \u201cDesign and rapid fabrication of integrated fiber-based EHD pumps \u201d in Proceedings of the Extended Abstracts of the CHI Conference on Human Factors in Computing Systems (Association for Computing Machinery 2025) pp. 1\u20135.","DOI":"10.1145\/3706599.3721200"},{"key":"e_1_3_2_60_2","doi-asserted-by":"publisher","DOI":"10.1109\/70.481753"},{"key":"e_1_3_2_61_2","doi-asserted-by":"publisher","DOI":"10.1109\/JMEMS.2015.2421641"},{"key":"e_1_3_2_62_2","doi-asserted-by":"publisher","DOI":"10.1007\/s11431-010-4096-z"},{"key":"e_1_3_2_63_2","doi-asserted-by":"crossref","unstructured":"R. W. Ogden \u201cElements of the theory of finite elasticity \u201d in Nonlinear Elasticity: Theory and Applications R. W. Ogden Y. B. Fu Eds. London Mathematical Society Lecture Note Series (Cambridge Univ. Press 2001) pp. 1\u201357.","DOI":"10.1017\/CBO9780511526466.002"},{"key":"e_1_3_2_64_2","first-page":"20170728","article-title":"Magic angles for fibrous incompressible elastic materials","volume":"474","author":"Horgan C. O.","year":"2018","unstructured":"C. O. Horgan, J. G. Murphy, Magic angles for fibrous incompressible elastic materials. Proc. A 474, 20170728 (2018).","journal-title":"Proc. A"},{"key":"e_1_3_2_65_2","doi-asserted-by":"publisher","DOI":"10.1177\/1045389X11435435"},{"key":"e_1_3_2_66_2","unstructured":"R. H. Gaylord Fluid actuated motor system and stroking device US Patent US2844126A (1958); https:\/\/patents.google.com\/patent\/US2844126A\/en."},{"key":"e_1_3_2_67_2","unstructured":"H. F. Schulte \u201cThe characteristics of the McKibben artificial muscle\u201d in The Application of External Power in Prosthetics and Orthotics (National Academy of Sciences\u2013National Research Council 1961) pp. 94\u2013115."},{"key":"e_1_3_2_68_2","doi-asserted-by":"publisher","DOI":"10.5254\/1.3542351"},{"key":"e_1_3_2_69_2","doi-asserted-by":"publisher","DOI":"10.1002\/adma.202003375"},{"key":"e_1_3_2_70_2","doi-asserted-by":"publisher","DOI":"10.1126\/sciadv.1600327"}],"container-title":["Science Robotics"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.science.org\/doi\/pdf\/10.1126\/scirobotics.ady6438","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,3,25]],"date-time":"2026-03-25T17:59:11Z","timestamp":1774461551000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.science.org\/doi\/10.1126\/scirobotics.ady6438"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,3,25]]},"references-count":69,"journal-issue":{"issue":"112","published-print":{"date-parts":[[2026,3,25]]}},"alternative-id":["10.1126\/scirobotics.ady6438"],"URL":"https:\/\/doi.org\/10.1126\/scirobotics.ady6438","relation":{},"ISSN":["2470-9476"],"issn-type":[{"value":"2470-9476","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,3,25]]},"assertion":[{"value":"2025-05-29","order":0,"name":"received","label":"Received","group":{"name":"publication_history","label":"Publication History"}},{"value":"2026-02-25","order":2,"name":"accepted","label":"Accepted","group":{"name":"publication_history","label":"Publication History"}},{"value":"2026-03-25","order":3,"name":"published","label":"Published","group":{"name":"publication_history","label":"Publication History"}}],"article-number":"eady6438"}}