Robot-assisted minimally invasive surgery is used to perform intricate surgical tasks through small incisions using long, slender instruments. The miniaturization of these instruments is advantageous to both surgeon and patient because smaller instruments reduce trauma to surrounding tissue, decrease patient recovery times, and can be used in confined spaces otherwise inaccessible using larger instruments. However, miniaturization of existing designs is limited by friction between moving parts, the volume occupied by the end effector, and manufacturing and assembly constraints. The objective of this work is to develop and analyze concepts that can be used in robot-assisted needlescopic surgery. The concepts are intended for instrument shafts no larger than 3 mm in diameter. An ideal concept is one with large ranges of wrist and gripping motion. Concepts should also minimize friction and swept volume while maintaining a focus on manufacturability and ease of assembly. Multiple concepts were generated and evaluated using a tree classification scheme, proof-of-concept prototypes, and simplified mathematical models. Three unique concepts were further developed and tested—the Split CORE Grips, the Inverted Flexure Grips, and the Crossed Cylinders Wrist. The two grip concepts are instruments that incorporate one rotational degree of freedom and one gripping degree of freedom. The wrist concept incorporates two rotational degrees of freedom and could be coupled with a single DOF grip mechanism to form a functional instrument. In addition to concept development, a variety of fabrication techniques were investigated to better understand the challenges that arise when designing and fabricating devices at the 3 mm scale. To augment existing techniques, a novel fabrication technique was developed which uses layers of lithographically patterned carbon nanotube (CNT) composite material to form a 3D part. This method was used to prototype some of the designs at a 1:1 size scale.



College and Department

Ira A. Fulton College of Engineering and Technology; Mechanical Engineering



Date Submitted


Document Type





minimally invasive surgical instrument, needlescopic surgery, robotics, carbon nanotube