Effects of Chemical Composition on the Electromechanical Properties of Microfluidically Synthesized Hydrogel Beads

This investigation demonstrates microfluidic synthesis of monodisperse hydrogel beads with controllable electromechanical properties. Hydrogel beads were synthesized using aqueous monomer solutions containing difunctional macromer, ionic liquid monomer, and photoinitiator. Electromechanical properties of these beads were measured at compression ratios up to 20% to examine their potential use in vibrational energy harvesters. Bead stiffness decreased dramatically as water content increased from 19% to 60%. As water content and compression ratio increased, electrical permittivity of beads increased, while resistivity decreased. As ionic liquid monomer concentration increased from 0% to 4%, relative permittivity increased by 30–45% and resistivity decreased by 70–80%.