Design optimization of a soft micro-robot for medical intervention

In this paper, a design method of a soft fluidic micro-robot (SMR) used for medical intervention in the context of cochlear implant insertion is proposed. Two centerlines are used: SMR's neutral axis and the helicoidally shaped pipe inside the cochlea called scala tympani (ST). The average distance between these two lines is defined as an objective function to be minimized. To achieve this, a cochlea implant has been hollowed-out to create an optimally shaped pneumatic chamber to be pressurized. The variation of the bending moment and second moment of area along the SMR's longitudinal axis have been employed to ensure that its curvature radius under pressure follows the ST's centerline. Finite element analysis is used to iterate over the parametric pneumatic chamber until the objective function is minimized. Simulated insertions have been conducted to test the optimal design and they shows that the proposed method may improve the insertion of straight wall electrode arrays by reducing the collisions with the anatomy. This is the first step toward the development of a closed loop active medical device for inner-ear intervention.