Toward a Millimeter-Scale Tendon-Driven Continuum Wrist with Integrated Gripper for Microsurgical Applications

Microsurgery, wherein surgeons operate on extremely small structures frequently visualized under a micro- scope, is a particularly impactful yet challenging form of surgery. Robot assisted microsurgery has the poten- tial to improve surgical dexterity and enable precise operation on such small scales in ways not previously possible [1], [2]. Clinical applications of microsurgery include intraocular surgery, fetal surgery, otology, laryn- geal surgery, neurosurgery, and urology. Intraocular microsurgery is a particularly challenging domain [3], [4]. Challenges arise, in part, due to the lack of dexterity that is achievable with rigid instruments inserted through the eye. The insertion point introduces a remote center of motion (RCM) constraint that pre- vents control over a tool-tip’s full pose (position and orientation) for conventional, straight instruments. Con- tinuum robots based on concentric tubes [5], magnetic actuation [6], and tendon-actuated stacked disks [7], [8] have been proposed for intraocular microsurgery in order to overcome this constraint, but are frequently limited in their local curvatures—an important consideration in constrained spaces. Inspired by these works, we present a new design for a millimeter-scale, dexterous wrist intended for micro- surgery applications. The wrist is based on recent ad- vances in tendon-driven continuum robot designs [9] and created via a state-of-the-art two-photon-polymerization (2PP) microfabrication technique. The 2PP 3D printing method enables our wrist to be constructed of flexible material, with complex internal geometries and critical features at the micron-scale (Fig. 1).