Rheological measurements were performed on an Anton Paar MCR 302 rheometer (Anton Paar, Torrance, USA) using cone-plate geometry (diameter: 10 mm, cone angle: 2°) for inks and parallel-plate geometry (diameter: 8 mm, gap size: 0.6 mm) for photocrosslinked hydrogels. Hydrogels were prepared by transferring 75 µL in a cylindrical polydimethylsiloxane (PDMS) mold (diameter: 8 mm, height: 1.5 mm), followed by UV light exposure for 5 min (302 nm, 8 W). For the rheological characterization, the hydrogel slab or an appropriate amount of ink was placed onto the lower plate of the rheometer. Excess sample volume of the precursor solution was trimmed after reaching the measuring gap between cone and plate. A solvent trap was employed to minimize water evaporation. Rheology data was acquired at 22 °C for the GelMA precursor and at 37 °C for GelMA/bPE formulations and hydrogels. All samples were pre-sheared by applying an oscillatory shear 𝛾 = 100% for 30 s, followed by 𝛾 = 1% for 5 min to reach steady state conditions. Amplitude sweeps (Figure and S7), with a strain amplitude 𝛾 ranging from 0.01-100%, were carried out at an angular frequency of 𝜔 = 1 rad•s -1 to assess the linear viscoelastic (LVE) regime. Frequency sweeps (𝜔 = 0.1-20 rad•s -1 ) were performed at a strain of 𝛾 = 1% (within the LVE regime), revealing the frequency-dependent shear moduli 𝐺′ and 𝐺′′ (Figure and S7) and the oscillatory complex viscosity 𝜂*. Shear-thinning behavior was quantified by fitting the linear region of the angular frequency-complex viscosity plot with the power law model (Figure ). A shear stress ramp ranging from 1-1000 Pa was applied to all precursor solutions to determine the yield point 𝜎 * . In the shear stress-viscosity diagram, the flow initiation point was computed by the intersection point between linear regressions of the plateau region (solid regime) and the viscosity-drop region (fluid regime) (Figure ). Rotational recovery measurements were conducted to simulate the timescale of recovery of deposited inks post-extrusion by applying a high shear rate of 𝛾̇ = 100 s -1 for 250 s, followed by a low shear rate of 𝛾̇ = 0.01 s -1 for 500 s.