Design of a mechanical clutch-based needle-insertion device.

Insertion of trocars, needles, and catheters into unintended tissues or tissue compartments results in hundreds of thousands of complications annually. Current methods for blood vessel cannulation or epidural, chest tube, and initial trocar placement often involve the blind pass of a needle through several layers of tissue and generally rely on distinguishable anatomic landmarks and a high degree of clinical skill. To address this simply and without the use of electronics, a purely mechanical clutch system was developed for use in medical devices that access tissue and tissue compartments. This clutch utilizes the surface contact of a buckled filament inside an S-shaped tube to transmit force from the filament (catheter/guide wire) to the tube (needle). Upon encountering sufficient resistance at the tip, such as dense tissue, the catheter buckles and locks within the tube, causing the filament and needle to advance as one. When the needle reaches the target tissue or fluid-filled cavity, the filament unlocks and slides freely into the target region while the needle remains stationary. A similar locking phenomenon has long been observed in drill strings inside drill shafts used by the oil-drilling industry, and oil industry models were adapted to describe the motion of this clutch system. A predictive analytical model was generated and validated with empirical data and used to develop prototypes of a complete device then tested in vitro on muscle tissue and in vivo on a porcine laparoscopic model with promising results.