A Magnetically-Actuated Coiling Soft Robot With Variable Stiffness

Peter Lloyd, Theodosia Lourdes Thomas, Venkatasubramanian Kalpathy Venkiteswaran, Giovanni Pittiglio, James H. Chandler, Pietro Valdastri, Sarthak Misra

Research output: Contribution to journalArticleAcademicpeer-review


Soft and flexible magnetic robots have gained significant attention in the past decade. These robots are fabricated using magnetically-active elastomers, are capable of large deformations, and are actuated remotely thus allowing for small robot size. This combination of properties is appealing to the minimally invasive surgical community, potentially allowing navigation to regions of the anatomy previously deemed inaccessible. Due to the low forces involved, one particular challenge is functionalizing such magnetic devices. To address this limitation we introduce a proof-of-concept variable stiffness robot controlled by remote magnetic actuation, capable of grasping objects of varying sizes. We demonstrate a controlled and reversible high deformation coiling action induced via a transient homogeneous magnetic field and a synchronized sliding nitinol backbone. Our soft magnetic coiling grasper is visually tracked and controlled during three experimental demonstrations. We exhibit a maximum coiling deformation angle of 400<inline-formula><tex-math notation="LaTeX">$^{\circ }$</tex-math></inline-formula>.

Original languageEnglish
Pages (from-to)3262-3269
Number of pages8
JournalIEEE Robotics and automation letters
Issue number6
Publication statusPublished - 2023


  • Continuum manipulators
  • Deformation
  • Elastomers
  • Grasping
  • Magnetic actuation
  • Magnetic continuum robots
  • Magnetization
  • Magnetoelasticity
  • Robots
  • Shape
  • Soft magnetic materials
  • Soft robots
  • Surgical robotics

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