Table 2.

Parameters that each method introduced can assess and their relevant characteristics. M*: Mixed or inconclusive reports in the literature. N: This method cannot be used for this characteristic. Y: This method can be used for this characteristic.

	Porosity	Pore Sizes	Pore Shape	Surface Area	Pore Throat Size	Fiber Diameter	Interconnectivity	Tortuosity	Other Parameters	Particularities
Gas Pycnometry	With caliper	N	N	N	N	N	N	N	Density
BET/BJH	Y	Y	N	Y	N	N	N	N		Resolution: 0.5 nm–2 µm
Hg-Intrusion	Y	Y	N	N	M*	N	N	M*		Resolution: 30 nm–0.2 mm Toxic, destructive, might deform nanoscaffolds
Liquid intrusion	Y	Y	N	N	M*	N	N	M*		Resolution: 1 nm–20 µm
Liquid extrusion	Y	Y	Y	Y	N	N	N	N	Permeability	Resolution: 100 nm–2 mm
Capillary flow	Y	M*	Y	Y	Y	N	N	N	Permeability	Resolution: 13 nm–0.5 mm
Liquid displacement	Y	N	N	N	N	N	N	N
Liquid pycnometry	Y	N	N	N	N	N	N	N
Gravimetry	With caliper	N	N	N	N	N	N	N
Apparent Volume	With caliper	N	N	N	N	N	N	N
Permeability method	N	M*	N	N	N	Y	N	N	Permeability
SEM	Only Surface	Only surface	N	N	N	Y	Qualitative	Qualitative	Anisotropy	Resolution: 1 nm. Can image cells. Can only assess surface of scaffold. Vacuum might shrink scaffolds.
TEM	N	N	N	N	N	Y	N	N		Only usable on single fibers. Resolution: 0.2 nm
AFM	N	N	N	Y	N	Y	N	N	Fiber nanostructure	Resolution: <1 nm
Micro-CT	Y	Y	Y	Y	Y	Y	Y	Y	All within resolution	Resolution: 1–3 µm. Thresholding difficulty. Can image cells.
Nano-CT	Y	Y	Y	Y	Y	Y	Y	Y	All within resolution	Resolution: <50 nm. Thresholding difficulty. Can image cells.
CLSM	Y	Y	Y	N	Y	Y	Y	Y	All within resolution	Resolution: 10 nm XY-plane, 800 nm Z-Axis. Scaffold must be made fluorescent, can image cells