FABRICATION AND STRENGTH-BASED DESIGN OF A MESO FORCEPS

A novel fabrication process and design optimization method for a mesoscale forceps is presented. This work is part of a larger research effort to design and fabricate nanoparticulate enabled surgical instruments using an iterative fabrication-design technique. The current paper focuses on the fabrication of thick (similar to hundreds of microns) two dimensional parts with large aspect ratios (length/width > 20). The paper also describes an optimization method that accounts for manufacturing requirements and material strength. The process begins with the fabrication of an array of molds on refractory substrates using a modified UV lithography technique. In parallel, engineered ceramic nanocolloidal slurries are prepared for gel-casting into the molds. Mold infiltration takes place via a squeegee technique adapted from screen printing with excess slurry removed using an ethanol bath. Finally, the photoresist molds are removed via pyrolysis, and ceramic parts sintered to full density. Employing this manufacturing technique for the compliant micro forceps design is advantageous because a large number of parts can be produced with large aspect ratios, sharp edges (similar to 1 mu m), and a resolution of 2 mu m. An optimization algorithm, using ANSYS optimization module, is formulated to determine the effect of dimensional parameters and material strength on the optimal design and predicted performance of the compliant meso forceps. Three ultimate strength values are separately implemented as a stress constraint in our optimization problem. Results conclude that our manufacturing process is capable of producing meso scale forceps considering the anticipated ultimate strength at this scale.