Abstract
By definition, surgery is an invasive procedure because it requires from the surgeon to make an incision in the patient's body to gain access to the surgical site. Minimally invasive surgery (MIS) strives to reduce trauma and recovery time by minimising the size and number of incisions. Access and the use of appropriate tools play a major role in the success of this objective.The tools currently in use are either straight and rigid elements, allowing a linear trajectory, or flexible, allowing complex curved or multi-curved trajectories. The flexible instruments used, such as flexible endoscopes, extend the scope of surgery and are particularly useful in less accessible areas. They also allow the incision to be made as close to the area of interest as possible.In the same way that a snake continually adapts the shape of the body as it moves forward, the shape of the instruments must evolve within the human body and therefore be fully controllable.A serial robotic design based on the use of compliant mechanisms with monolithic structures and shape-memory alloy actuators has proven to be an interesting way to built such architecture. The use of compliant mechanisms has allowed the design of elementary modules to meet the constraints of dimensioning and downscaling, where memory alloys are suited for their small size and high energy density. The designed modules have three stable states and are extremely repeatable and mechanically robust. Their supperposition allowed for high precision discrete displacements without the need for sensors (open loop control).In order to optimise the elementary modules a design of a new version of the flexible mechanisms was carried out and an approach using electroactive polymers to replace shape memory alloys was considered to minimise the assembly phase.The complex geometry of the mechanisms and their monolithic nature make additive manufacturing, and in particular 3D printing, a suitable manufacturing process. This parsimonious manufacturing process is part of an approach to manufacturing affordable and patient-specific robots. A prototype has been designed to validate the proposed approach.