Epoxy resins as stamps for hot embossing of microstructures and microfluidic channels

Fabrication of micro total analysis systems using plastic substrates has become more prevalent in the recent literature with the driving force being the development of inexpensive disposable analytical devices. Hot embossing is one polymer micro-fabrication method that has shown significant promise in this area because identical polymeric devices can be produced using a master to repeatedly stamp an image into a number of plastic substrates/materials. One major disadvantage of hot embossing in a research setting is the time and expense needed to produce a stamping tool able to withstand the temperature and stress of the embossing process. This paper describes a method of producing an epoxy stamp that is relatively inexpensive, rapid to produce and durable enough to withstand multiple embossing cycles (n > 50). The epoxy-stamping tool can be micro-molded from either a positive or a negative imaged master and is compatible with a number of materials including SU-8 resist on silicon, PDMS or glass. The low viscosity of the pre-cured epoxy permits the reproduction of microstructures with dimensions below 1 μm in size and allows for the transfer of these small structures to PMMA by hot embossing without loss in detail. The stamp fabrication process can be performed in less than 4 h. When the process is combined with rapid device prototyping capabilities of SU-8/silicon micro-fabrication the entire process of microchip fabrication process (design to device) may be completed in 24-48 h.