Most of the existing fabrication techniques for tissue engineering scaffolds require the use of organic solvents that may never be fully removed even after long leaching hours. The residues of these organic solvents may reduce the ability of biological cells to form new tissue. In this study, interconnected porous structures were created using solid-state foaming and ultrasound. The interconnectivity was verified with dye test. The pore sizes of the foams ranged from 300 to 500 μm. Permeability measurements were also performed to quantify the interconnectivity using a system developed in house. The achieved average permeability of PLA foams with 300 μm pore size is 3.1×10-12 m2. The bigger the closed pores are, the easier ultrasound can make them open. There is an optimum temperature range in which ultrasound will enhance the interconnectivity of the solid-state foam the most efficiently. An ultrasound cavitation model was proposed as the dominant pore opening mechanism and was used to explain the temperature effects and pore size effects. The combined solidstate foaming and ultrasound processing provides a way to fabricate porous polymer for potential tissue engineering applications.

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