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Report

Teaser, summary, work performed and final results

Periodic Reporting for period 2 - INCANA (Insect-inspired capillary nanostamping)

Teaser

Summary

Stamping is an everyday life process â€“ stamping stamps is an example for this. Stamping has also emerged as a versatile technique to pattern surfaces in materials science, nanotechnology and microtechnology. Stamping can be carried out in such a way that surfaces are topographically patterned by embossing. Moreover, surfaces can be chemically patterned by stamping inks onto them. Chemically patterned surfaces are of tremendous practical importance as they may show tailorable wettability, tailorable anti-fouling properties, or tailored affinity to cells. Chemically patterned surfaces may be employed for spatially resolved preconcentration sensing or as model surfaces for the investigation of cellular interactions. It is also possible to transfer the chemical patterns into the underlying substrates by selective etch processes. State-of-the-art stamping methods for the chemical patterning of surfaces typically rely on solid stamps with topographically patterned contact surfaces. The functional materials to be transferred onto the counterpart surfaces to be patterned need to be adsorbed onto the outer surfaces of the solid stamps. Thus, solid stamps need to be reloaded with inks frequently by time-consuming procedures. Often, only molecular monolayers of the material to be stamped can be deposited onto counterpart surfaces by classical stamping methods, and the range of inks that can be processed in this way is limited. This project aims at overcoming these drawbacks by transferring functional principles of insect feet to lithographic stamping. Insect feet adhere to vertical walls and ceilings by contact formation via a large number of hairy contact elements. Moreover, insects deploy secretions for adhesion management through the hairy contact elements to the contact interfaces. Thus, after detachment of the insect feet arrays of secretion droplets remain on the counterpart surface. In this project, spongy porous stamps mimicking insect feed will be designed for insect-inspired capillary nanostamping. Insect-inspired capillary nanostamping will furthermore be developed as a high throughput stamping process to pattern surfaces with a broad range of inks. In this way, limitations of classical stamping processes will be overcome. Sacrificial self-assembling template structures, so far used for modes of surface patterning for which classical stamping is not feasible, will at least partially be replaced by insect-inspired capillary nanostamping. The ultimate objective is to establish insect-inspired capillary nanostamping an environmentally friendly high-throughput process for the production of functional surfaces and porous materials.

Work performed

So far, porous stamps consisting of polymers and of glass were designed and successfully used. It could be demonstrated that insect-inspired capillary nanostamping can be carried out manually under ambient conditions without the need of expensive instrumentation. For example, in this way chemically patterned surfaces were generated onto which nanoparticles were formed by templated dewetting. Arrays of fullerene nanoparticles, which are of interest for solar cells, could directly be stamped. By stamping of a metal precursor combined with a special etching process silicon wafers were topographically patterned. We could demonstrate that onto these topographically patterned silicon surfaces persistent and scratch-resistant identity labels or quick response codes may be generated by inkjet printing. It could, moreover, be demonstrated that not only inks but even parts of the stamps themselves can be lithographically deposited onto counterpart surfaces. This variation of the stamping process allows lithographic deposition of arrays of three-dimensional objects that can be further functionalized in many ways for applications in fields such as catalysis and bioanalytics.

Final results

Insect-inspired capillary nanostamping will extend the range of inks that can be stamped and will, as a low-tech approach that can be carried out by simple means, facilitate surface patterning by stamping.