Open tracheostomy (OT) is considered the traditional way and golden standard for treating airway obstruction patients. However, OT has many unavoidable drawbacks, including strict performing scenarios, significant scarring, and the risk of surgeon infection. Percutaneous dilation tracheostomy (PDT) emerges, with advantages including a lower cost, smaller scarring, and better protection of surgeons from inflecting by aerosol. However, the outside-in puncture manner of PDT has a risk of piercing the post-tracheal wall and the esophagus with uncontrolled force. Additionally, locating tracheal rings and determining the puncture site externally can be challenging for certain patients, such as those who are obese or have undergone neck surgery, while this procedure typically relies on palpation and the surgeon's expertise. Hence, to improve the safety and simplicity of tracheostomy, a minimally-invasive endotracheal inside-out flexible needle-driving system towards microendoscope-guided robotic tracheostomy (MERT) has been proposed in this paper. Guided by an optical coherence tomography (OCT) probe and a microendoscope, the robot inserts into the trachea and performs an inside-out puncture using a flexible needle. The robot can work through a standard endotracheal tube (ETT), and the puncture direction of the flexible needle is variable. Kinematics and statics models of the flexible needle have been derived, and the minimum position errors generated in the kinematics and statics validation experiments are$0.57 \pm 0.21 \mathbf{~ m m}$and$0.27 \pm 0.21 \mathbf{~ m m}$. Finally, a porcine trachea puncture experiment is carried out, and the feasibility of the proposed system is verified.

In situ tissue biopsy with an endoluminal catheter is an efficient approach for disease diagnosis, featuring low invasiveness and few complications. However, the endoluminal catheter struggles to adjust the biopsy direction by distal endoscope bending or proximal twisting for tissue sampling within the tortuous luminal organs, due to friction-induced hysteresis and narrow spaces. Here, we propose a pneumatically-driven robotic catheter enabling the adjustment of the sampling direction without twisting the catheter for an accurate in situ omnidirectional biopsy. The distal end of the robotic catheter consists of a pneumatic bending actuator for the catheter’s deployment in torturous luminal organs and a pneumatic rotatable biopsy mechanism (PRBM). By hierarchical airflow control, the PRBM can adjust the biopsy direction under low airflow and deploy the biopsy needle with higher airflow, allowing for rapid omnidirectional sampling of tissue in situ. This paper describes the design, modeling, and characterization of the proposed robotic catheter, including repeated deployment assessments of the biopsy needle, puncture force measurement, and validation via phantom tests. The PRBM prototype has six sampling directions evenly distributed across 360 degrees when actuated by a positive pressure of 0.3 MPa. The pneumatically-driven robotic catheter provides a novel biopsy strategy, potentially facilitating in situ multidirectional biopsies in tortuous luminal organs with minimum invasiveness.