Post-processing of polymer foam tissue scaffolds with high power ultrasound: a route to increased pore interconnectivity, pore size and fluid transport

Abstract: We expose thick polymer foam tissue scaffolds to high power ultrasound and study its effect on the openness of the pore architecture and fluid transport through the scaffold. Our analysis is supported by measurements of fluid uptake during insonification and imaging of the scaffold microstructure via x-ray computed tomography, scanning electron microscopy and acoustic microscopy. The ultrasonic treatment is found to increase the mean pore size by over 10%. More striking is the improvement in fluid uptake: for scaffolds with only 40% water uptake via standard immersion techniques, we can routinely achieve full saturation of the scaffold over approximately one hour of exposure. These desirable modifications occur with no loss of scaffold integrity and negligible mass loss, and are optimized when the ultrasound treatment is coupled to a pre-wetting stage with ethanol. Our findings suggest that high power ultrasound is a highly targetted and efficient means to promote pore interconnectivity and fluid transport in thick foam tissue scaffolds.