CAREER: Manufacturing Tools for the Next Generation of Tissue Engineering, Manufacturing Education for the Next Generation of Engineers

Ohio State University, The, Columbus OH

Investigators

Abstract

It is now conceivable to fabricate engineered tissues inside the human body through a "keyhole" surgery with a robotic, endoscopic 3D printer. This long-term vision has broad implications for healthcare; the way in which surgeons replace diseased and damaged tissue could be forever transformed. This Faculty Early Career Development (CAREER) award supports a study on the dynamics of material delivery in an endoscopic 3D printer, a necessary step to realize this vision. This award also supports an innovative program for high school students to design an assistive device for patients with a specific ambulation disability. An endoscopic 3D printer is composed of a rod-like end-effector (to deliver a fluid-phase material through a "keyhole" surgical site) and a chain of kinematic elements (to position this end-effector). With this form-factor, an endoscopic 3D printer will have dynamic coupling between the positioning and material delivery sub-systems of the end-effector (not observed in a standard 3D printer), and a higher fluidic resistance in the material delivery sub-system than a standard 3D printer. The first research objective is to establish the analytic input-output relationship for the end-effector and compare the output value to a computational model. To achieve this objective, the established Herschel-Bulkley constitutive model for non-Newtonian colloidal fluids will be used to describe the material while geometric constraints and boundary conditions relevant to an endoscopic 3D printer end-effector will be imposed. The output (flowrate) prediction from the input-output relationship will be compared to the predicted output value from a multi-physics computational model. The second objective is to test the hypothesis that the output rise time of a two-degree-of-freedom material delivery actuator (designed to mitigate the higher fluidic resistance) will be significantly lower than the output rise time of a nominal material delivery actuator. This hypothesis will be tested by experiments. The output rise time for the two different material delivery actuators will be measured by machine vision under dynamic flowrate references. The third objective is to establish the input-output relationships of the complete endoscopic 3D printer and compare outputs values to an experiment. To achieve this objective, a quasi-static kinematic model will be used to describe the serial chain of kinematic elements, which will then be coupled with the end-effector input-output relationship established in objectives one and two. Multiple output predictions (six positions and one flowrate) from the input-output relationships will be compared to measured values from experiments performed on a prototype endoscopic 3D printer.