Overcoming the Force Limitations of Magnetic Robotic Surgery: Magnetic Pulse Actuated Collisions for Tissue-Penetrating-Needle for Tetherless Interventions

The field of magnetic robotics aims to obviate physical connections between the actuators and end-effectors. Such tetherless control may enable new ultraminimally invasive surgical manipulations in clinical settings. While wireless actuation offers advantages in medical applications, the challenge of providing sufficient force to magnetic needles for tissue penetration remains a barrier to practical application. Applying sufficient force for tissue penetration is required for tasks such as biopsy, suturing, cutting, drug delivery, and accessing deep-seated regions of complex structures in organs such as the eye. To expand the force landscape for such magnetic surgical tools, an impact force-based suture needle capable of penetrating in vitro and ex vivo samples with 3-degrees-of-freedom (DOF) planar motion is proposed. Using custom-built 14 and 25 G needles, generation of 410 mN penetration force is demonstrated, a 22.7-fold force increase with more than 20 times smaller volume compared with similar magnetically guided needles. With the Magnetic Pulse Actuated Collisions for Tissue-penetrating (MPACT)-Needle, gauze mesh suturing onto an agar gel is demonstrated. In addition, the tip size is reduced to 25 G, a typical needle size for eye interventions, to demonstrate ex vivo penetration in a rabbit eye towards corneal injections and transscleral drug delivery.