Surface Molding of Microscale Hydrogels with Microactuation Functionality.

This work describes the fabrication of numerous hydrogel microstructures (μ-gels) via a process called "surface molding." Chemically patterned elastomeric-assembly substrates were used to organize and manipulate the geometry of liquid prepolymer microdroplets, which, following photo-initiated crosslinking, maintained the desired morphology. By adjusting the state of strain during the crosslinking process, a continua of structures could be created using one pattern. These arrays of μ-gels have stimuli-responsive properties that are directly applicable to actuation where the basis shape and array geometry of the μ-gels can be used to rationally generate microactuators with programmed motions. As a method, "surface molding," represents a powerful addition to the soft-lithographic toolset that can be readily applied to the simultaneous synthesis of large numbers of geometrically and functionally distinct polymeric microstructures.