Fig. 1: Conceptual illustration of the Helixoft microrobotic system for stiffness tuning and active steering of microcatheters during interventional surgeries.

The system comprises four modules: a a Helixoft microrobot; b a robotic catheter manipulator; c a magnetic control module including electromagnetic coils and a permanent magnet mounted on a robotic arm; d an imaging module based on a C-arm computed tomography setup (C-arm CT) and an endoscopic mini-camera. The Helixoft microrobot is mountable onto commercial microcatheters alongside microsurgical tools (e.g., mini-camera, electrode, and fibre). Stiffness tuning of the Helixoft is achieved through the magnetically controlled helical motion of its rigid helix component, which dynamically wraps around the soft microtube section. The magnetic fields also control the microcatheter steering, while the robotic manipulator controls the microcatheter advancement. R denotes the rotational field, and S denotes the static field. The purple curved arrow indicates the rotation direction of the helix, while the green arrow denotes its translational motion direction. The red–blue gradient circular arrow represents the rotating magnetic field, and the red–blue gradient straight arrow indicates the static magnetic field. The orange arrow denotes the deflection direction of the tube. Anatomical elements (lung, brain, uterus) are adapted from Freepik (free license).