{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,15]],"date-time":"2026-04-15T18:08:04Z","timestamp":1776276484681,"version":"3.50.1"},"reference-count":42,"publisher":"American Association for the Advancement of Science (AAAS)","issue":"100","license":[{"start":{"date-parts":[[2026,3,19]],"date-time":"2026-03-19T00:00:00Z","timestamp":1773878400000},"content-version":"vor","delay-in-days":365,"URL":"https:\/\/www.science.org\/content\/page\/science-licenses-journal-article-reuse"}],"content-domain":{"domain":["www.science.org"],"crossmark-restriction":true},"short-container-title":["Sci. Robot."],"published-print":{"date-parts":[[2025,3,19]]},"abstract":"<jats:p>Torque and continuous rotation are fundamental methods of actuation and manipulation in rigid robots. Soft robot arms use soft materials and structures to mimic the passive compliance of biological arms that bend and extend. This use of compliance prevents soft arms from continuously transmitting and exerting torques to interact with their environment. Here, we show how relying on patterning structures instead of inherent material properties allows soft robotic arms to remain compliant while continuously transmitting torque to their environment. We demonstrate a soft robotic arm made from a pair of mechanical metamaterials that act as compliant constant-velocity joints. The joints are up to 52 times stiffer in torsion than bending and can bend up to 45\u00b0. This robot arm continuously transmits torque while remaining flexible in all other directions. The arm\u2019s mechanical design achieves high motion repeatability (0.4 millimeters and 0.1\u00b0) when tracking trajectories. We then trained a neural network to learn the inverse kinematics, enabling us to program the arm to complete tasks that are challenging for existing soft robots, such as installing light bulbs, fastening bolts, and turning valves. The arm\u2019s passive compliance makes it safe around humans and provides a source of mechanical intelligence, enabling it to adapt to misalignment when manipulating objects. This work will bridge the gap between hard and soft robotics with applications in human assistance, warehouse automation, and extreme environments.<\/jats:p>","DOI":"10.1126\/scirobotics.ads0548","type":"journal-article","created":{"date-parts":[[2025,3,19]],"date-time":"2025-03-19T18:01:19Z","timestamp":1742407279000},"update-policy":"https:\/\/doi.org\/10.34133\/aaas_crossmark","source":"Crossref","is-referenced-by-count":28,"title":["Bridging hard and soft: Mechanical metamaterials enable rigid torque transmission in soft robots"],"prefix":"10.1126","volume":"10","author":[{"ORCID":"https:\/\/orcid.org\/0009-0000-9062-3647","authenticated-orcid":true,"given":"Molly","family":"Carton","sequence":"first","affiliation":[{"name":"Department of Mechanical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Ave., Cambridge, MA 02139, USA."},{"name":"Department of Mechanical Engineering, University of Maryland, 4289 Campus Dr., College Park, MD 20742, USA."}]},{"ORCID":"https:\/\/orcid.org\/0009-0006-1032-6583","authenticated-orcid":true,"given":"Jakub F.","family":"Kowalewski","sequence":"additional","affiliation":[{"name":"Department of Mechanical and Industrial Engineering, Northeastern University, 390 Huntington Ave., Boston, MA 02115, USA."}]},{"given":"Jiani","family":"Guo","sequence":"additional","affiliation":[{"name":"Department of Mechanical Engineering, University of Washington, 3900 E Stevens Way NE, Seattle, WA 98195, USA."}]},{"ORCID":"https:\/\/orcid.org\/0009-0002-2078-5290","authenticated-orcid":true,"given":"Jacob F.","family":"Alpert","sequence":"additional","affiliation":[{"name":"Department of Mechanical and Industrial Engineering, Northeastern University, 390 Huntington Ave., Boston, MA 02115, USA."}]},{"given":"Aman","family":"Garg","sequence":"additional","affiliation":[{"name":"Department of Mechanical Engineering, University of Washington, 3900 E Stevens Way NE, Seattle, WA 98195, USA."}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6246-7819","authenticated-orcid":true,"given":"Daniel","family":"Revier","sequence":"additional","affiliation":[{"name":"Department of Computer Science, University of Washington, 185 E Stevens Way NE, Seattle, WA 98195, USA."}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1266-2071","authenticated-orcid":true,"given":"Jeffrey Ian","family":"Lipton","sequence":"additional","affiliation":[{"name":"Department of Mechanical and Industrial Engineering, Northeastern University, 390 Huntington Ave., Boston, MA 02115, USA."}]}],"member":"221","reference":[{"key":"e_1_3_2_2_2","first-page":"1","article-title":"Trimmed helicoids: An architectured soft structure yielding soft robots with high precision, large workspace, and compliant interactions","volume":"1","author":"Guan Q.","year":"2023","unstructured":"Q. Guan, F. Stella, C. Della Santina, J. Leng, J. Hughes, Trimmed helicoids: An architectured soft structure yielding soft robots with high precision, large workspace, and compliant interactions. NPJ Robot. 1, 1\u201313 (2023).","journal-title":"NPJ Robot."},{"key":"e_1_3_2_3_2","doi-asserted-by":"publisher","DOI":"10.1126\/scirobotics.adi5908"},{"key":"e_1_3_2_4_2","doi-asserted-by":"publisher","DOI":"10.1126\/scirobotics.aan3028"},{"key":"e_1_3_2_5_2","doi-asserted-by":"publisher","DOI":"10.1109\/TASE.2016.2600527"},{"key":"e_1_3_2_6_2","doi-asserted-by":"crossref","unstructured":"S. Hamdule S. S. Goilkar \u201cAn overview of the untapped potential of soft robotic arms with integration of machining tools\u201d in Machining and Additive Manufacturing (Springer Nature 2024) pp. 107\u2013115.","DOI":"10.1007\/978-981-99-6094-1_11"},{"key":"e_1_3_2_7_2","doi-asserted-by":"crossref","unstructured":"E. Krotkov D. Hackett L. Jackel M. Perschbacher J. Pippine J. Strauss G. Pratt C. 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