Scanning electron microscopy images of laser micro-machined PLA scaffolds with 150 l m (a), 300 l m (b), and 600 l m (c) pore sizes with 15.9% porosity in the machined area (4 mm 3 4 mm). Scale bar 5 1 mm. 

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... general when ablation occurs, a plume of the ablated material is created. After ablation, this mate- rial can then redeposit on the surface of the ablated area. Redeposition of the material onto the substrate can result in the substrate having a melted morphol- ogy. Examples of a scaffold with redeposition post- laser ablation are shown in Figs. 4 and 6c. Laser machining of the electrospun PLA resulted in pro- duction of scaffolds with highly ordered pore sizes and locations (Fig. 5). High ratios of Z-motion velocity to laser pulse rate resulted in a rippling shape along the axis of the pore due to poor overlap of zones of ablation (Fig. 4). Decreasing the Z-motion velocity or increasing the laser pulse rate results in greater over- lapping of consecutive laser pulses and a more cylin- drical pore shape (Fig. 6). Smaller diameter pores were elliptical and larger diameter pores exhibited a circular profile due to laser rastering (Table 2). Micro- machined pore sizes displayed high intra-sample preci- sion and overall a low range of error for all ...