Electroresponsive behavior of calcium alginate hydrogel under electric field

Calcium alginate hydrogels were prepared by soaking the membranes of sodium alginate in CaCl₂ solutions of different concentration, and their swelling ratio and electroresponsive behavior of the hydrogels in NaCl solution were studied. The results indicate that the water take-up of the hydrogels increase with increasing the concentration of NaCl solution and decreased with increasing the concentration of crosslinker of CaCl₂ solution. The hydrogels swollen in NaCl solution bend toward cathode under a non-contact direct current electric field. The bending speed and strain of the hydrogels increase as the applied voltage increases, but decrease as the concentration of CaCl₂ increases, and reach their maximum values when the ionic strength of NaCl solution is 0.03. Under a cyclically varying electric field, the hydrogels exhibit good reversible bending behavior.