The Department of Mechanical Engineering in Partial Fulfillment of the Requirements for the Degree of Bachelor of Science in as Recommended by the Department of Mechanical Engineering

This study was performed to determine whether the particle size of the starting collagen powder or the material of molds used during freeze-drying had effects on the scaffold pore structure. Collagen particles were separated by size prior to slurry making using a sieve with 1000 um openings, and scaffolds were made using both metal pans and polysulfone trays, two commonly used molds. The mean and variation of pore diameter and interconnectivity of freezedried scaffolds were compared to determine the relationship between particle size or mold material and the resulting pore diameter, for a specific same freeze-drying condition (viz., temperature). Knowing these relationships will permit a better control of pore size during fabrication, allowing researchers to design scaffolds with greater predictability and specificity. Thesis Supervisor: Myron Spector Title: Senior Lecturer of Mechanical Engineering, Professor of Orthopaedic Surgery at Harvard Medical School