The Feasibility of Using Pulsed-Vacuum in Stimulating Calcium-Alginate Hydrogel Balls

Area of Science:

• Materials Science
• Chemical Engineering
• Biomaterials

Background:

• Alginate hydrogels are widely used in various applications.
• Controlling the external gelation process is crucial for tailoring hydrogel properties.
• Pulsed-vacuum stimulation (PVS) is an emerging technique for modifying material properties.

Purpose of the Study:

• To investigate the effect of pulsed-vacuum stimulation (PVS) on the external gelation of calcium-alginate (Ca-Alg) hydrogel balls.
• To determine the optimal working pressure for PVS in Ca-Alg hydrogel formation.
• To understand the relationship between PVS parameters and hydrogel characteristics.

Main Methods:

• Ca-Alg hydrogel balls were subjected to PVS at different working pressures (8, 35, 61, 101 kPa) and cycles.
• Diffusion coefficients (D) of calcium cations (Ca2+) were measured.
• Weight reduction (WR) and volume shrinkage (Sv) rates were quantified.
• Textural properties and structural morphology (SEM) were analyzed.

Main Results:

• Calcium ion diffusion coefficients (D) decreased over time, particularly in the first three hours.
• Weight reduction (WR) and volume shrinkage (Sv) showed a direct correlation with D values and a strong linear relationship with each other (R > 0.91).
• The highest WR and Sv were observed at 8 kPa, while 61 kPa yielded the most favorable overall results.
• SEM revealed structural differences, with 8 kPa showing more deformation and larger cavities compared to 61 kPa.

Conclusions:

• Pulsed-vacuum stimulation (PVS) effectively modifies the external gelation of calcium-alginate hydrogels.
• Working pressure significantly influences calcium ion diffusion, weight reduction, and volume shrinkage.
• A working pressure of 61 kPa appears optimal for achieving desired Ca-Alg hydrogel characteristics through PVS.
• PVS is a promising technology for controlling Ca-Alg hydrogel properties.