Table 1.

Qualitative characterization of line extrusions (with a 27G nozzle and a travel feed rate of 8 mm s⁻¹) reveals the existence of optimal GelMA concentration/extrusion pressure pairings.

	Characteristics of printed lines
GelMA concentration	Noncontinuous flow, uneven thickness: beads instead of lines	Optimal pressure, continuous flow, constant thickness	Excessive outpour, uneven thickness, large chunks in lines
10% w/v GelMA	60 psi	80 psi	100 psi
15% w/v GelMA	80 psi	100–110 psi	120 psi
20% w/v GelMA	100 psi	130 psi	—a

^aRequired extrusion pressure exceeded the capabilities of the extruder.