Design and Characterization of a Miniature Dual-chamber Pneumatic Actuator for Minimally Invasive Surgical Devices

Advances in minimally invasive surgery require the development of enhanced miniature steerable robotic surgical instruments. Novel actuator technologies are necessary to safely and accurately guide instruments to difficult-to-access anatomy to enable new surgical procedures. Concentric McKibben actuators have been introduced recently to actuate miniature surgical devices while enabling efficient use of space via a working channel integrated in the empty space of the muscle core. These muscles have shown initial promise for miniaturization and accurate control, but with some challenges in pneumatic sealing, stroke range, hysteresis characteristics, and generated force compared to traditional McKibben muscles. Initial concentric muscle designs focused on natural orifice surgical procedures where a certain level pneumatic leakage from the muscle was acceptable. The working channel of existing designs is also too small for surgical interventions requiring the introduction of relatively large (1.5 − 2 mm diameter) instruments. This article describes the design of an innovative multi-compartment McKibben muscle. This design is fully pneumatically sealed, enabling use in a wider range of surgical devices. The design is proposed and the obtained performance is evaluated. The prototype actuator is capable of producing up to 11.9 Newtons of force and 9.9 mm of displacement at a speed of 22.5 mm/sec. Directions for future work are sketched as well.