Microcontact printing

Microcontact printing (or μCP) is a form of soft lithography that uses the relief patterns on a master polydimethylsiloxane (PDMS) stamp or Urethane rubber micro stamp[1] to form patterns of self-assembled monolayers (SAMs) of ink on the surface of a substrate through conformal contact as in the case of nanotransfer printing (nTP).

However, the unprotected silicon regions can be etched, and the photoresist stripped, which would leave behind a patterned wafer for creating the stamp.

This mixture consists of a short hydrosilane crosslinker that contains a catalyst made from a platinum complex.

After pouring, the PDMS is cured at elevated temperatures to create a solid polymer with elastomeric properties.

During the transfer the carbon chains of the thiol align with each other to create a hydrophobic self-assembling monolayer (SAM).

Microcontact Printing has several advantages including: After this technique became popular various limitations and problems arose, all of which affected patterning and reproducibility.

Also, applying too much vertical pressure on the stamp during printing can cause the raised relief features to flatten against the substrate.

During the curing process the stamp can potentially shrink in size leaving a difference in desired dimensions of the substrate patterning.

Ink diffusion from the PDMS bulk to the surface occurs during the formation of the patterned SAM on the substrate.

Once the ink has been applied to the substrate the SAM layer acts as a resist to common wet etching techniques allowing for the creation of high resolution patterning.

[8] Various proteins have been proven to be suitable inks and are applied to various substrates using the microcontact printing technique.

Polylysine, immunoglobulin antibody, and different enzymes have been successfully placed onto surfaces including glass, polystyrene, and hydrophobic silicon.

PDMS stamps can mold growth material into micro chambers that then capture single-celled organisms for imaging.