Fig. 2. Rheology and shape retention properties of bacteria-laden Flink used for 3D printing.

(A and B) Rheological properties of the individual components (1 wt % κ-CA, 1 wt % HA, and 1 wt % FS) in LB bacterial medium (A) and in combination as Flink at concentrations of 1, 2, and 3 wt % for each individual constituent (hereafter called 3, 6, and 9 wt % Flinks, respectively) (B). The steady-state flow behavior of the inks is measured by viscosity curves at increasing and decreasing shear rates. The elastic (G′) and viscous (G″) moduli are measured by oscillatory amplitude sweeps (strain, 0.01 to 1000%; angular frequency, 1 rad/s). (C) Left: To simulate printing conditions, alternating high (70 s⁻¹) and low (0.1 s⁻¹) shear rates in steady-state rotation mode were applied to 3, 6, and 9 wt % Flinks. Right: Instantaneous recovery of the viscoelastic network of 6 wt % Flink is shown by a sudden shear process in a steady state (70 s⁻¹), followed by an oscillatory time sweep. (D) Left: Dynamic yield stresses of different Flink concentrations measured in strain-controlled measurements. Right: The effect of yield stress and elasticity on structure retention in printed filaments for different Flinks.