Spatiotemporally controlled electrodeposition of magnetically driven micromachines based on the inverse opal architecture

Abstract

We describe a double template-assisted electrodeposition of porous metal microstructures. The method combines two-dimensional photolithography and electrophoretic assembly of polystyrene beads, in order to confine the electrochemical growth of a porous magnetic cobalt–nickel alloy within well-defined microscale boundaries. Polystyrene beads are electrophoretically deposited onto a sulfonate derivatized gold substrate where a patterned photoresist layer (first template) is applied. The polystyrene beads trapped in the first template act as the second template, and cobalt–nickel alloy is electrochemically grown through the voids between the beads. After removal of both templates, magnetic microstructures with well-defined shapes and porosity are successfully obtained. Additionally, we demonstrate the capabilities of these magnetic microstructures as wireless cargo microtransporters by loading their pores with a stimulus-responsive hydrogel. Magnetic manipulation experiments are also demonstrated.