Flexible surgical instruments for safe & effective minimally invasive surgery

In recent years, flexible surgical tools are drawing significant attention in research, and they exhibit great potential to obtain better outcomes from minimally invasive surgery (MIS) procedures. The common favourable feature of these flexible tools, being complaint, allows them interacting with the tissues or organs safely during surgery. Although this compliance makes the flexible tools safer than traditional rigid tools, the effectiveness of such flexible tools might be hindered inevitably. This indicates the development of safe and effective flexible surgical tools is demanding but challenging. Application-based requirements and proper engineering approaches need to be considered for development of flexible and effective surgical tools. In this context, the ultimate goal is to develop MIS flexible tools, which can perform inspection, diagnosis, and treatment in a safer and more effective manner. To this purpose, this thesis details about the development of two typical surgical instruments: a flexible variable stiffness manipulator, and a flexible morphing grasper. Firstly, the development of a flexible manipulator is presented, which is endowed with a variable stiffness functionality to fit requirements of different stages of a surgery. Secondly, the development of a morphing surgical grasper is presented, which can passively increase its contact area upon clutching force, so as to redistribute stress applied on tissue, thus mitigating the stress concentration issue posed by traditional rigid graspers.