Replication Techniques through Soft-Lithography

The LaNN laboratory is one of the most important nanofabrication centers in Italy and it’s active in several research fields.

At LaNN, a soft lithography process has been finely tuned in order to realize high-fidelity replicas of several 3D nano-optical elements fabricated by electron beam lithography (EBL).

Starting from the original masters, spiral phase plates (SPP), computer-generated holograms (CGH) and diffractive optical elements (DOE) have been precisely reproduced. The optical behavior of the fabricated replicas has been tested to be comparable to that of the original SPP, CGH and DOE masters.

The technique uses an elastomeric mold, made of silicone (polydimethylsiloxane or PDMS) bearing a micro or nanostructured relief on its surface. Given the soft nature of the mold, a perfect contact with the surface is easily achieved without the need to apply particularly high pressures, even on rather rough or curved surfaces. The resolution obtainable with the various soft-lithographic techniques typically reaches 100 nm. Soft-lithography is characterized by an extremely wide range of structurable materials ranging from polymers to gels, from self-assembled monolayers to proteins and cells.

Soft-lithography allows the realization of micro or nanometric structures, starting from pre-fabricated molds and exploiting polymer materials, called “soft”. For soft-lithography, LaNN typically uses the “replication molding” process with elastomeric polymers, such as PDMS. This is one of the most common materials for the fabrication of microfluidic devices thanks above all to its transparency, bio-compatibility and the ability to accurately replicate nanometric structures.

The instrument supplied with the LaNN is the UV Light Curing System DYMAX PC, supplied with a 400W lamp.


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