PDMS stamp

Sarfus image of streptavidin deposited by soft lithography with PDMS stamp.

PDMS stamps are pieces of Polydimethylsiloxane (PDMS) that have been patterned usually against a master to form a relief pattern used in soft lithography. This PDMS stamp can be used in either its current form as a relief surface for techniques such as Micro Contact Printing or can also be attached to an external source by tubing so that liquid may be passed through channels on its surface. In this second case it will often be laminated to a surface so that chemistry can be performed on that surface producing a pattern of the PDMS stamp on to the surface. Alternatively a PDMS stamp can be laminated to a second piece of PDMS to form a contained device. It is possible to pattern PDMS with nanometre resolution. Many techniques have been developed to modify the basic setups to perform a range of tasks such as assays on small volumes. These kinds of devices are often referred to as microfluidic devices. Because of the small dimensions of these devices flow is laminar not turbulent which can lead to many useful properties; however, this reduces the ability of fluid streams to mix.