Evaluation of design aspects of modular pneumatic soft robotic endoscopes

Minimally Invasive Surgery (MIS) and Natural Orifice Transluminal Endoscopic Surgery (NOTES) are gradually replacing purely open surgery. One of the key components in MIS or NOTES is an endoscope. Soft robotic endoscopes can provide accuracy and safe interaction with human soft tissue. In this study, the design aspects of pneumatic endoscopic soft robots are investigated. These aspects are the radial constraints (sheathing) of pneumatic chambers in the soft robotic module, the number of chambers and the geometric volume of the chambers. The evaluation is considering the influence of these design aspects on the bendability of the soft robot. Besides the module bending performance, other aspects are considered, including; reducing the pneumatic pressure applied for bending, minimizing the module dimensions, and using the design in multi-module configuration in endoscopic applications. These design aspects are evaluated using finite element models that are validated experimentally based on tests performed in this study and previous studies. The results show that despite the fact that the 4-chamber module provides higher moment arm while bending, using three chambers is more optimal for control and pneumatic hardware requirements. It was observed that outer sheathing provides more bending at lower pneumatic pressure. Moreover, the cylindrical chamber design provides higher bending capabilities, but other volumetric designs can be considered in case more space is needed for miniaturizing the design. In conclusion, the results in this study provide new insight in the design aspects of the pneumatic chambers of soft robotic endoscopes which is beneficial for bringing conceptual designs into clinical practice.