Fabrication of Polymeric 3-D Micro-Structures Using Ferrofluid Molds

In this paper, we report a new and simple fabrication method for 3-D polymeric microstructures using low viscosity mineral oil-based ferrofluids in combination with polydimethylsiloxane (PDMS) and UV curable epoxy. The diameter and height of ferrofluid spikes/domes which usually form upon the application of a magnetic field was controlled by a micromachined membrane having holes of various dimensions. Holes or various dimensions (60, 100, and 200 µ m) were fabricated in a thin silicon membrane covering a ferrofluid reservoir. The heights of fabricated polymeric microstructures corresponding to the above mentioned hole sizes were equal to the hole diameters, while their base diameters were reduced by 10-30%. This approach provides a new technique to easily fabricate various size 3-D micro-structures on the same plane by controlling the magnetic field strength, ferrofluid viscosity, and hole dimensions.