Magnetic Micro-Driller System for Nasolacrimal Duct Recanalization

Primary acquired nasolacrimal duct obstruction (PANDO) is the commonest cause of obstructive tearing and can lead to infections including dacryocystitis, cellulitis and postoperative endophthalmitis. External or endoscopic dacryocystorhinostomy (DCR) is the current standard treatment of PANDO. However, DCR is technically challenging, invasive, and not without risks, especially epistaxis and recurrent obstruction. We designed and constructed a magnetic micro-driller system for nasolacrimal duct (NLD) recanalization as a minimally invasive alternative to conventional treatment. The drilling microrobot consists of a 3D printed helical tip and a permanent magnet. A magnetic actuation system with three electromagnets is developed to well accommodate the human anatomy and generate three-dimensional dynamic magnetic fields along the NLD. To navigate the microrobot safely inside the NLD, the micro-driller is integrated with a guidewire and a feed drive system to control its motion. Furthermore, a force sensor is installed on the proximal end of the guidewire to report the force signal, through which the state of the micro-driller can be detected and the control input can be decided. Our results show that the guide-wired microrobot can navigate through the NLD phantom and remove the blockage automatically. The proposed strategy provides a microrobot-assisted endoluminal solution for NLD recanalization with improved safety by introducing the magnetic manipulation and force control method.