Micro Contact Printing (µCP)

Function

Micro Contact Printing is a simple and cost saving method to functionalize surfaces selectively. Features on the micrometer scale can be fabricated reproducibly. Different substances like molecules, nanoparticles, proteins and adhesives are printable. The surface of metal, glass or polymer substrates can be planar or curved.

The Printing Process

The casting of a micro machined surface (master, usually a silicon chip) is made of a prepolymer (e.g. silicone) (1). After being cured the polymer stamp is covered with an ink (2). The stamp is brought into conformal contact with the targeted surface where the molecules of the ink adsorb. These molecules could, for example, form a self assembled monolayer (3). Their functionality depends on the application (4).

The perfect stamp

Resolution and accuracy of the micro contact printed structures depend strongly on the physical properties of the stamp. The most important design parameters are fill factor, aspect ratio, pitch, size and stiffness. We have extensive experience in the design and fabrication of stamps optimized for various processes, substrates and molecular inks.

Silicone stamp

Applications

Patterning of Metallic Thin Films

Micro contact printing allows for the patterning of metallic thin films on planar and curved surfaces with  high resolution and throughput. One can either stamp self-assembling monolayers which act as etch masks or deposit a precursor (seed layer) to subsequently build up copper or nickel layers by electroless plating. The latter has the advantage that no vacuum processes are necessary. Other common applications are different surface functionalizations and bioassays.

Gold seams (CHIMIA 2002, 10, 527)
Patterned chromium oxide
Electroless copper patterns

Translucent Conducting Paths

Metals are not only highly electrically conducting but also highly reflective. Therefore they appear shiny. For metallic electrical paths to be transparent they have to be smaller than the resolution of the human eye. This corresponds to a maximum line width of 5 µm. Micro contact printing is a cost effective method to fabricate such structures. Gratings that have been fabricated in this way show optical and electrical properties very similar indium tin oxide (ITO), one of the most common transparent electrically conducting materials.

Translucent conducting grid with 2 µm line widths

Micro Contact Printing Tool

Since 2008 the MNT is engaged in the design, development and fabrication of micro contact printing tools. Right now the next generation is being developed at MNT. This new tool features an alignment of all rotative and translative degrees of freedom of the stamp to the targeted surface. The measurement of the contact force integrated in the printing head allows for a force controlled printing. All relevant process parameters such as printing time and contact force are controlled and can be adjusted via a dedicated software. The printing process can be monitored thanks to integrated optics and a CMOS camera. Due to the modular design various options are available: substrate heating and cooling, fluorescence analysis and special printing heads for curved substrates. We are happy to develop your customized tool according to your specific needs.

Flyer: Micro Contact Printing Tool

Specifications

Stamp Size1 mm2 to 10 cm2
Minimal Feature Size< 1 µm up to a few mm
Force Control50 mN to 10 N
Translation in x / y Direction
50 mm
Translation in z Direction
25 mm
Min. Step Size
< 1 µm
Rotation around z-Axis
+ / -  180°
Rotational Resolution
< 5 Arcseconds
Tilt around x / y-Axis+ / - 5°
Tilt-Resolution< 0.5 Arcseconds
Optical Magnification0.7x – 4.5x
Micro Contact Printing tool Mark III