Unidirectional dynamic stiffness modulation enables easily insertable and conformally attachable spinal bioelectronic device

Unidirectional dynamic stiffness modulation enables easily insertable and conformally attachable spinal bioelectronic device | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Article Unidirectional dynamic stiffness modulation enables easily insertable and conformally attachable spinal bioelectronic device Sunguk Hong, Sungah Park, Mingeun Cho, Matthew Ko, Seongjae Lee, and 7 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8259356/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 04 Mar, 2026 Read the published version in npj Flexible Electronics → Version 1 posted 12 You are reading this latest preprint version Abstract Neural interfaces for monitoring and modulating spinal nerve activity are increasingly being designed to be flexible and stretchable to enhance their biomechanical compatibility and integration. However, excessive flexibility introduces practical limitations such as difficulty in insertion into narrow spinal spaces and long-term electrical instability, hindering real-world applications. In this study, we developed a spinal nerve interface by incorporating a liquid-metal conductor and dynamic stiffness-based variable-compliance structure, which can address the challenges of current flexible neural interface technologies. During insertion, the dynamic stiffness enhancer minimizes unintended buckling and ensures minimally invasive implantation into the intended target. The proximity of the proposed device to the spinal cord increases as it flexes automatically and rapidly in a humid environment. The liquid-metal conductor maintained stable electrical properties in freely moving rats, ensuring reliable and sustained functionality. This study lays the foundation for practical, fully implantable spinal bioelectronics designed with a focus on ease of implantation and long-term functionality. Physical sciences/Engineering Physical sciences/Materials science Variable stiffness-based neural interface with liquid-metal is developed for improved ease of handling and electrical stability Full Text Additional Declarations No competing interests reported. Supplementary Files supplementarymaterialsv4.docx SupplementaryMovie1.avi SupplementaryMovie2.mp4 SupplementaryMovie3.mp4 Cite Share Download PDF Status: Published Journal Publication published 04 Mar, 2026 Read the published version in npj Flexible Electronics → Version 1 posted Editorial decision: Revision requested 26 Dec, 2025 Reviews received at journal 25 Dec, 2025 Reviews received at journal 24 Dec, 2025 Reviewers agreed at journal 18 Dec, 2025 Reviews received at journal 18 Dec, 2025 Reviewers agreed at journal 16 Dec, 2025 Reviewers agreed at journal 16 Dec, 2025 Reviewers agreed at journal 16 Dec, 2025 Reviewers invited by journal 16 Dec, 2025 Editor assigned by journal 12 Dec, 2025 Submission checks completed at journal 03 Dec, 2025 First submitted to journal 02 Dec, 2025 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-8259356","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":562647010,"identity":"670e7e69-9899-4270-9a71-210f78481583","order_by":0,"name":"Sunguk Hong","email":"","orcid":"","institution":"Pohang University of Science and Technology (POSTECH)","correspondingAuthor":false,"prefix":"","firstName":"Sunguk","middleName":"","lastName":"Hong","suffix":""},{"id":562647017,"identity":"7f163eb2-9d89-486a-8892-7cc48fcc6053","order_by":1,"name":"Sungah Park","email":"","orcid":"","institution":"Pohang University of Science and Technology 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However, excessive flexibility introduces practical limitations such as difficulty in insertion into narrow spinal spaces and long-term electrical instability, hindering real-world applications. In this study, we developed a spinal nerve interface by incorporating a liquid-metal conductor and dynamic stiffness-based variable-compliance structure, which can address the challenges of current flexible neural interface technologies. During insertion, the dynamic stiffness enhancer minimizes unintended buckling and ensures minimally invasive implantation into the intended target. The proximity of the proposed device to the spinal cord increases as it flexes automatically and rapidly in a humid environment. The liquid-metal conductor maintained stable electrical properties in freely moving rats, ensuring reliable and sustained functionality. This study lays the foundation for practical, fully implantable spinal bioelectronics designed with a focus on ease of implantation and long-term functionality.\u003c/p\u003e","manuscriptTitle":"Unidirectional dynamic stiffness modulation enables easily insertable and conformally attachable spinal bioelectronic device","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-12-20 02:48:00","doi":"10.21203/rs.3.rs-8259356/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-12-26T17:31:17+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-12-26T02:13:22+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-12-24T06:52:59+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"172938244131216909714269168199796925961","date":"2025-12-19T00:25:31+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-12-18T09:05:19+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"217365464983497761770961513115493672386","date":"2025-12-17T03:16:41+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"240114828113732677176636036387380293606","date":"2025-12-17T01:55:42+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"157080520477528591054792121567062882698","date":"2025-12-17T00:55:01+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-12-16T23:55:41+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-12-12T18:06:13+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-12-03T16:17:30+00:00","index":"","fulltext":""},{"type":"submitted","content":"npj Flexible Electronics","date":"2025-12-02T10:27:47+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"npj-flexible-electronics","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"npjflexelectron","sideBox":"Learn more about [npj Flexible Electronics](http://www.nature.com/npjflexelectron/)","snPcode":"41528","submissionUrl":"https://submission.springernature.com/new-submission/41528/3","title":"npj Flexible Electronics","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"NPJ","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"5ffbc06b-62e6-4736-a401-1b97f525cbc1","owner":[],"postedDate":"December 20th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[{"id":59918130,"name":"Physical sciences/Engineering"},{"id":59918131,"name":"Physical sciences/Materials science"}],"tags":[],"updatedAt":"2026-03-09T16:11:19+00:00","versionOfRecord":{"articleIdentity":"rs-8259356","link":"https://doi.org/10.1038/s41528-026-00557-1","journal":{"identity":"npj-flexible-electronics","isVorOnly":false,"title":"npj Flexible Electronics"},"publishedOn":"2026-03-04 15:58:07","publishedOnDateReadable":"March 4th, 2026"},"versionCreatedAt":"2025-12-20 02:48:00","video":"","vorDoi":"10.1038/s41528-026-00557-1","vorDoiUrl":"https://doi.org/10.1038/s41528-026-00557-1","workflowStages":[]},"version":"v1","identity":"rs-8259356","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8259356","identity":"rs-8259356","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}