Hydrogel suspensions as an electro-rheological fluid

Concentrated suspensions of swollen-in-water polyelectrolyte gels are shown to behave a new electro-rheological fluid. Without electric current the suspension apparent viscosity is high, while upon switching current the apparent viscosity drastically decreases. The change of apparent viscosity is due to the reversible contraction of the gel in the presence of an electric current. Under a 20–100 mA current, a suspension of sodium polyacrylate gel particles can decrease its apparent viscosity by more than 100 times.