Physics

We observe that microcontact printing is a tool used by physicist for many applications. For example, it is used to realize flexible electronics like :

  • flash memories
  • field emission device
  • touchless control interface
  • transistor.

It is also used during the layer deposition process. For example, in the case of atomic layer deposition or to metallize (electroless or not), µCP can be a powerful tool. Another application field is optics. Indeed, it is possible to fabricate micro lens or optical negative index components thanks to microcontact printing. Some optical effects are reached thanks to µCP like SERS (Surface enhanced Raman Spectroscopy).

It is also possible to realize some hydrophilic/hydrophobic pattern on different substrate for micro droplet manipulation.

For all these cases, the trend is to control the process at the wafer-scale. µCP is more and more a standard tool for physicist.

Fabrication of Microlens Arrays by Localized Hydrolysis in Water Droplet Microreactors

Abstract

We report a facile self-assembly strategy for fabricating TiO2 microlens arrays by localized hydrolysis of TiCl4 precursor in water droplets. Microcontact printing was used to define hydrophilic areas on a substrate for space resolved hydrolytic reaction. The water droplets served as the templates, reactant, and microreactors. Highly ordered TiO2 microlens arrays could be produced, which exhibit excellent ability to focus light. Because both size and shape of the final TiO2 microlens can be controlled by the printed chemical pattern and the precursor concentration, it is possible to define TiO2 microlens arrays with different imaging properties. This new method shows attractive features of simplicity, low cost, and requires no heating process, hence is suitable for a range of applications.

Link

Fabrication of Microlens Arrays by Localized Hydrolysis in Water Droplet Microreactors

Microcontact Printing: Microcontact Printing of Ultrahigh Density Gold Nanoparticle Monolayer for Flexible Flash Memories

Abstract

V. A. L. Roy and co-workers show on page 3556 how uniform monolayers of alkanethiol-protected gold nanoparticle arrays can be used as microcontact-printable chargingtrapping layers for application in flash memory. Large-area close-packed gold nanoparticles are first transferred to a poly(dimethysiloxane) stamp and then onto a flexible substrate. A large memory window and long retention times have been obtained due to the enhanced trapping sites with almost no lateral leakage, indicating the great potential for scaling down the current state-of-art flash memory.

Link

Microcontact Printing: Microcontact Printing of Ultrahigh Density Gold Nanoparticle Monolayer for Flexible Flash Memories

Photoreversible fragmentation of a liquid interface for micro-droplet generation by light actuation

Abstract

We describe a method to induce by light a reversible switch from a continuous two-phase laminar flow to a droplet generating regime, in microfluidic devices with a usual water-in-oil flow focusing geometry. It consists in adding a photosensitive surfactant to the aqueous phase to modulate using light the interfacial energy between flowing liquids and the microfluidic substrate. We show that UV irradiation induces liquid fragmentation into monodisperse water microdroplets and that many cycles of reversible and rapid switches (<2 s) between continuous laminar flows and stable droplet regimes can be realized. By spatially controlling the application of the light stimulus, we also demonstrate the first spatially resolved remote induction of droplet generation.

Link

Photoreversible fragmentation of a liquid interface for micro-droplet generation by light actuation

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