Three-Dimensional Silicone Device Fabrication and Interconnection Scheme for Microfluidic Applications Using Sacrificial Wax Layers
Abstract A simple room-temperature procedure is reported herein for formation of true three-dimensionality of “microfluidic components” and complete microfluidic systems in silicone elastomer, this is achieved by molding the plastic to simply encapsulate a pre-formed network of sacrificial wax threads or other connected wax configurations which are ultimately to become micro channels, microfluidic components and cavities in the plastic motherboard. When these wax sacrificial areas are etched away with acetone, precise cavities, channels, and capillaries result with direct arbitrary three-dimensionality. This method leads also to a simple and effective external interconnection scheme where ordinary fused silica tubes may be press-fitted into the surface opening to withstand high pressure. An array of micro channels having circular cross sections with diameters of 100, 150 and 200 microns, membrane type valves, pinch valves, mixing chambers and reservoirs for fluid storage were molded in silicone elastomer using wax filaments. The wax filaments were dissolved in acetone after the silicone elastomer became hardened, leaving the micro channels, valves, mixing chambers and reservoirs in the silicone elastomer. This scheme gives the flexibility of allowing multi stacks of components (motherboards) while being able to control the channel lengths within the stacks as desired.