Ecoresorbable smart fluids with controlled electroresponsive properties by various metal doping†
Electrorheological (ER) fluids can be used in applications such as shock absorbers, haptic devices, and prosthetic limbs; however, the disposal of conventional ER-fluid constituents poses environmental and health risks. Herein, ecoresorbable smart fluids have been developed that consist of SiO2/TiO2 hollow nanoparticles (HNPs), doped with various biodegradable metals (Mg, Zn, and Fe) as electroresponsive materials and soybean oil as a carrier fluid. The presence of these metals in the metal-doped HNPs-based smart fluids significantly enhance their electroresponsive behavior, compared to their undoped counterparts; this is attributable to their improved dielectric properties and near-optimum electrical conductivities. The ER behavior of these ecoresorbable smart fluids can be described by the Wagner model. Moreover, the metal dopants minimally impact the high colloidal stability achieved by the porous structures of the HNPs in the ER fluids. To the best of our knowledge, this is the first study to develop degradable ER fluids. Exciting avenues for future research include the development of commercial applications for these green smart fluids.