Concentric Tube Robots for Minimally Invasive Surgery

INTRODUCTION The human body was not designed to facilitate surgical repair. Thus, in order to minimize collateral damage to healthy tissue, many interventions require following complex curved paths through tissue and body lumens to reach surgical targets. The smallest existing instrument technologies utilizing this approach are comprised of catheters and endoscopes for passing through body lumens and flexible needles for steering along curved paths through tissue. While these technologies provide substantial benefit to the patient, they also possess limitations on the types of interventional tasks that they can perform. For example, steerable needles rely on tissue reaction forces to bend and so cannot steer inside a body cavity. Catheters can be designed to steer inside a cavity, but their flexibility limits the forces they can apply to tissue. Thus, both types of devices have similar interventional capabilities – they can deliver a drug or device (e.g., stent) and perform ablation, but they are limited in terms of the surgical tools that they can use and the tissue manipulations that they can perform. Recently, a new class of robots for minimally invasive surgery has been developed called concentric tube robots [1,2]. These robots are comparable in diameter to steerable needles and catheters, but differ in construction since they are formed from concentric, telescoping, curved superelastic metal tubes. The shape of these robots is a smooth three-dimensional curve that can be controlled by rotating and translating the individual tubes with respect to each other. While their construction makes these robots significantly stiffer than conventional catheters, the ability to precisely control robot shape enables safe navigation through either tissue or body lumens. Tools and devices are deployed through the central lumen of the robot that serves as a working channel. Consequently, this robotic technology has broad potential for clinical use throughout the body including cardiac surgery [13-15] and neurosurgery [8]. This paper provides a brief summary of our progress to date in developing this technology.