Walter Bircher, BS1, Alex Adams1, Thomas Frederick, MS1, Mark Reichenbach, BS1, Shane Farritor, PhD1, Tammy Kindel, MD, PhD2, Dmitry Oleynikov, MD2. 1University of Nebraska-Lincoln, 2University of Nebraska Medical Center (UNMC)
INTRODUCTION: We have designed a novel multi-tool forearm for an insertable surgical robot with suction, irrigation, and grasping capabilities. Several generations of our miniature surgical robots, which have two dexterous arms and can be inserted into the abdominal cavity through a single incision site, have successfully performed porcine cholecystectomies and colectomies. The arms are very dexterous, but previous robots have been limited to one tool per robot arm, a cautery tool and a grasper. Tool use studies have shown that in laparoscopic cholecystectomies, a suction/irrigation device was used directly after a hook cautery 87.5% of the time. Thus, it is very important to include suction and irrigation capabilities in insertable robots to enable complete surgical procedures through a single incision. Furthermore, by combining multiple tools in one forearm, less time is spent switching and moving tools during surgery.
METHODS AND PROCEDURE: A robot forearm was designed with an irrigation tube directly in-line with a modified grasper, which becomes the tube tip when closed (Figure). Suction capability was tested by aspirating up to 50mL of water with the forearm from a dish at varying depths of grasper submersion. The outcome measure was the ratio of liquid to air in the syringe, with the amount of air aspirated correlating to leaks in the system. To test irrigation, we expelled 50mL of water from the syringe through the grasper, while monitoring the mechanism for leaks.
RESULTS With full submersion of the grasper, the suction device was able to fully aspirate all water without air leak. The system was only 20% efficient with the tip of the grasper submerged, indicating an air leak between the teeth of the closed grasper. The irrigation component was fully operational with no leakage of water. Grasper testing demonstrated good clamping force while holding position.
CONCLUSIONS: We have successfully developed a first-generation, multi-tool forearm with grasping, suction, and irrigation capabilities for use in a miniature robot. Future development is needed in improving the seal of the closed teeth when suctioning at the tip, to reach our goal of 90% efficiency.
Figure (A) Device functioning as a grasper (B) Grasper closed for suctioning and irrigation