Endotracheal Untethered Retractable Drill Mechanism Toward Robot-Assisted Endoluminal Inside-Out Dilatational Tracheostomy

Current percutaneous dilatational tracheostomy (PDT) exposes clinicians to respiratory pathogens, increasing infection risks. Roboticizing PDT can reduce these risks but requires precise control to avoid esophageal injury during puncture. We present a robotic system with a distal wireless retractable drill (RD) for inside-out puncture, allowing simultaneous insertion of the drill and tracheal cannula. The RD uses a four-stage retractable structure, inspired by bamboo shoots, achieving a penetration depth of 28.95 mm, with a compact folded length of 13.81 mm. Controlled by an external permanent magnet (EPM), the RD applies magnetic torque (up to 15 N $\cdot $ mm) with stable hydraulic operation. A spiral augmentation improves drilling efficiency, and the dynamics model accurately predicts forces and torque. Torque measurements also indicate dilation stages. Robotic-assisted positioning, integrating magnetic and optical tracking, provides adequate alignment. Ex vivo tests on pig tracheas showed successful perforation, offering a safer, automated alternative to manual PDT while reducing complications and the learning curve.