technique suitable for the layered manufacturing of polymeric scaffolds with a predesigned anatomical shape and a controlled
dual-scale porous structure [2, 3]. CAWS is based on the computer-controlled deposition of a polymeric solution filament into a
coagulation bath (typically a non-solvent of the polymer) to build
up 3D scaffolds with a layer-by-layer process. During its extrusion
through a needle immersed in the coagulation bath, the solution
filament solidifies because of polymer desolvation caused by solvent/non-solvent exchange that leads to the separation of the
initial thermodynamically stable solution into two phases with different composition (Fig. 1). Under a critical composition of the
polymeric solution, a polymer-lean phase is dispersed into a continuous polymer-rich phase finally resulting in the formation of a local
microporosity in the polymeric matrix. The final dual-scale scaffold
architecture is characterized by a fully interconnected network of
macropores, with size and geometry determined by the predefined
lay-down pattern, and a micro-/nanoporosity that can be tailored
by acting on different phase inversion parameters.
The optimization of customized manufacturing protocols has
led to the development of a set of layered scaffold prototypes made
Fig. 1 Scaffold fabrication by CAWS: (a) schematic representation of the fiber coagulation process during
CAWS showing the needle translating at a resulting deposition velocity (V dep ) and at a given initial distance
from the collection plane (Z 0 ) and the polymeric solution extruded at a given feed rate (F sol ) directly in a
coagulation bath. (b) Schematic representation of a detail of the solvent/non-solvent interface where J 1 is the
non-solvent flux and J 2 is the solvent flux, and X is the position of the interface at different time points. (c)
Schematic representation of a designed scaffold architecture showing structural parameters corresponding to
given deposition parameters: interfiber deposition distance (d xy ), lay-down pattern angle (α), interlayer needle
translation (d Z )
102
Dario Puppi and Federica Chiellini
dual-scale porous structure [2, 3]. CAWS is based on the computer-controlled deposition of a polymeric solution filament into a
coagulation bath (typically a non-solvent of the polymer) to build
up 3D scaffolds with a layer-by-layer process. During its extrusion
through a needle immersed in the coagulation bath, the solution
filament solidifies because of polymer desolvation caused by solvent/non-solvent exchange that leads to the separation of the
initial thermodynamically stable solution into two phases with different composition (Fig. 1). Under a critical composition of the
polymeric solution, a polymer-lean phase is dispersed into a continuous polymer-rich phase finally resulting in the formation of a local
microporosity in the polymeric matrix. The final dual-scale scaffold
architecture is characterized by a fully interconnected network of
macropores, with size and geometry determined by the predefined
lay-down pattern, and a micro-/nanoporosity that can be tailored
by acting on different phase inversion parameters.
The optimization of customized manufacturing protocols has
led to the development of a set of layered scaffold prototypes made
Fig. 1 Scaffold fabrication by CAWS: (a) schematic representation of the fiber coagulation process during
CAWS showing the needle translating at a resulting deposition velocity (V dep ) and at a given initial distance
from the collection plane (Z 0 ) and the polymeric solution extruded at a given feed rate (F sol ) directly in a
coagulation bath. (b) Schematic representation of a detail of the solvent/non-solvent interface where J 1 is the
non-solvent flux and J 2 is the solvent flux, and X is the position of the interface at different time points. (c)
Schematic representation of a designed scaffold architecture showing structural parameters corresponding to
given deposition parameters: interfiber deposition distance (d xy ), lay-down pattern angle (α), interlayer needle
translation (d Z )
102
Dario Puppi and Federica Chiellini