Characterization of Magnetoelectric Cantilever for Use as an Ablation Tool in Minimally Invasive Surgery

Despite great strides in materials science and control, an automated surgical tool is still in the fiction pages due to the lack of a surgical tool employing a self-sensing actuator. In an attempt to fill this void, we present magnetoelectric materials as a solution for designing surgical tools. This paper discusses our ongoing work to model the dynamics of the magnetoelectric material for use in a control loop. The surgical tool is a two-segment magnetoelectric cantilever in which one of the two magnetoelectric segments is attached to a fixed support called the base. A floating segment called the cutting tip is attached to the base using a flexible hinge. The two-segment tool is placed in a remote magnetic field to generate the cutting force in the magnetoelectric tip. Displacement in the tip generates a proportional electrical response from the piezoelectric layer and serves as the self-sensing signal. The self-sensing signal from the two segments is used for operating the tool in closed loop operation. The dynamic characterization of the magnetoelectric cantilever in bending is derived from constitutive equations for the magnetoelectric material. The strain terms in the constitutive equation is expressed using generalized coordinates in the shape function for the cantilever in bending mode. The equivalent stiffness of the magnetoelectric cantilever is derived using variational principles for calculating the tip displacement in the cantilever.