Research and Development Engineer
N106 MILLENNIUM SCI COMPLEX
UNIVERSITY PARK, PA 16802
Soft lithography involves making a three dimensional structure in a flexible polymer such as PDMS or PU from a master mold of silicon or thick photoresist. The flexible polymer structures can be used for microfluidic channels or a "stamp" for transferring a liquid "ink" which could be a sol-gel or a functionalized chemical.
PDMS structure from SU-8 or KMPR master: This is the simplest of all methods in that it typically uses a low cost transparency mask and contact photolithography to expose a pattern in either SU-8 or KMPR resist on a silicon wafer. This resist/wafer combo is then the master for making the PDMS structure.
PDMS from all silicon master: This method results in a more robust and higher fidelity all silicon master realized by photolithography and deep reactive ion etching of silicon. The PDMS structure is then cast into the robust all silicon master. Poly urethane (PU) structures are usually cast from PDMS sub-molds. The PU has properties that are desirable in certain sol-gel stamping applications.