Robotic Manipulator with Multiple Instruments for NOTES

Abolfazl Pourghodrat, Carl A Nelson, PhD, Dmitry Oleynikov, MD. University of Nebraska Lincoln.

Decreasing the degree of invasiveness of surgery is believed to improve patient outcomes. Transitioning from open surgery to Minimally Invasive Surgery (MIS), Natural Orifice Transluminal Endoscopic Surgery (NOTES) is a future trend in surgery due to the potential benefits it offers. NOTES has not been well adopted yet in the operating room due to several barriers, including the difficulty of frequent tool interchanges typically required in laparoscopic procedures, and the potential associated trauma to the patient.

In an effort to overcome this problem a few multi-function manipulators capable of carrying multiple tools have been designed and built. Previous designs are still too big to be easily inserted via natural orifices, slow in actuation and tool exchange, and expensive mainly due to use of miniature electric motors with limited power. In contrast, we have developed a hydraulically-driven manipulator (seen in Figure 1) which is half the size in outer diameter and length (55 mm in length and 14 mm in outer diameter), mush faster, cost-effective, and with no on-board electronics. The manipulator is capable of carrying four different 2-mm laparoscopic tools such as grasper and scissors. The manipulator is intended to attach to a bi-manual snake robot for NOTES which is under development. This would make a total of eight instruments available at the surgical site. A master-slave system has been developed to enable the surgeon to remotely control the robotic manipulator, apply instruments, and interchange them. All electronics are integrated in the master system which is placed ex-vivo, eliminating the risk of leaking electricity and transferring heat produced by electronics to tissues, and easing the sterilization requirements.

Bench-top testing on tissue analogs shows promising results. Time for advancing/retracting an instrument was under 4 seconds, and jaw opening/closure was under 1.5 seconds. Two different laparoscopic instruments (grasper and scissors) were interchanged successfully. Future work includes evaluation of the system in animal models.