Microfabrication of 3D Structures Using Novel Thermoplastic Elastomers

The use of thermoplastic elastomer gels as advanced substrates for construction of complex microfluidic systems is shown. These gels are synthesized by combining inexpensive polystyrene – (polyethylene / polybutylene) – polystyrene triblock copolymers with a hydrocarbon oil for which the ethylene/butylene midblocks are selectively miscible. The insoluble styrene endblocks phase separate into localized domains to form an optically transparent, viscoelastic, and biocompatible 3-D network (similar to PDMS), with the further advantage of melt-processability in the vicinity of 100 °C. Microfluidic devices can be fabricated in under 5 minutes by making an impression of the negative relief structures on a heated master mold. Multiple impressions can be made against different masters to construct geometries incorporating variable-height features, as well as intricate 3-D multilayered structures. Thermal and mechanical properties are tunable over a wide range through proper selection of gel composition.