Table 2.

Stiffness values of bio-inks at different scales

Material	Modulus	Modulus value	Dimension	Test mode	Condition	Concentration (w/w)	Refs.
					MW
PEGDA	E	6.5-30 MPa	Nanoscale	AFM	700 Da	*	[97]
	E	36 kPa	Macroscale	Compression	2000 Da	15.0%	[98]
	G	10 kPa	Macroscale	Compression	2000 Da	15.0%
	E	200-400 kPa	Macroscale	Tension	3000 Da	20.0%	[99]
	E	40 kPa	Macroscale	Tension	6000 Da	5.0%	[100]
	E	200 kPa	Macroscale	Tension	6000 Da	10.0%
	E	320 kPa	Macroscale	Tension	6000 Da	15.0%
	E	430 kPa	Macroscale	Tension	6000 Da	20.0%
					Temperature
GelMA	E	133 kPa	Nanoscale	AFM	25°	10.0%	[101]
	E	171 kPa	Nanoscale	AFM	25°	20.0%
	E	2.86 ± 0.1 kPa	Macroscale	Compression	25°	5.0%	[102]
	E	2.41 ± 0.38 kPa	Macroscale	Compression	37°	5.0%
	E	288.24 ± 62.34 kPa	Macroscale	Compression	25°	30.0%
	E	216.81 ± 10.28 kPa	Macroscale	Compression	37°	30.0%
	E	2.08 ± 0.43 kPa	Macroscale	Tension	25°	5.0%
	E	1.67 ± 0.56 kPa	Macroscale	Tension	37°	5.0%
	E	264.74 ± 11.08 kPa	Macroscale	Tension	25°	30.0%
	E	226.80 ± 39.97 kPa	Macroscale	Tension	37°	30.0%
Agarose	E	168 kPa	Nanoscale	AFM	25°	1.00%	[101]
	E	230 kPa	Nanoscale	AFM	25°	2.00%
Alginate	G	0.203 ± 0.013 kPa	Macroscale	Compression	20°	0.70%	[103]
	G	1.300 ± 0.129 kPa	Macroscale	Compression	20°	1.50%
	G	3.010 ± 0.084 kPa	Macroscale	Compression	20°	3.00%
Collagen (Type I)	E	~200 Pa	Nanoscale	AFM	20°	0.20%	[104]
	E	~500 Pa	Nanoscale	AFM	20°	0.30%
	E	~800 Pa	Nanoscale	AFM	20°	0.40%

Abbreviations: AFM, atomic force microscopy; E, elasticity modulus; G, shear modulus; MW, molecular weight. *Poly(ethylene glycol) diacrylate (PEGDA) of this molecular weight is liquid.