Rapid replication of master structures by double casting with PDMS.

We present a simple method for fast and precise replication of microfluidic master structures for moulding or soft embossing by double casting of microstructured masters with polydimethylsiloxane (PDMS). The significant achievement is a simple approach to inverse a given microstructure multiple times by means of PDMS-based soft lithography utilising hydroxypropylmethylcellulose (HPMC) as non texturing release agent. A series of PDMS copies have been generated from different silicon layouts with excellent reproducibility and precision, even submicron structures were well reproduced. The replicas were successfully applied in hot embossing and soft lithography of microfluic devices. Hence, we believe this technique is ideally suited for the economic replication of precious master structures (master sharing) commonly used in soft lithography and hot embossing.