Continuous Nanoparticle Assembly by a Modulated Photo-Induced Microbubble for Fabrication of Micrometric Conductive Patterns

The laser-induced microbubble technique (LIMBT) has recently been developed for micro- patterning of various materials. In this method, a laser beam is focused on a dispersion of nanoparticles leading to the formation of a microbubble due to laser heating. Convection currents around the microbubble carry nanoparticles so that they become pinned to the bubble/substrate interface. The major limitation of this technique is that, for most materials, a non-continuous deposition is formed.

We found that controlling the construction and destruction of the microbubble, through modulation of the laser, enables the formation of continuous patterns by preventing the microbubble from being pinned to the deposited material. When applied on a dispersion of Ag nanoparticles (that do not produce continuous microstructures without modulation) continuous electrically conductive lines were formed. Furthermore, the line width is narrower than achieved by the standard non-modulated LIMBT. This approach can be applied to the direct-write fabrication of micron-size conductive patterns in electronic devices, without the use of photolithography.