Colloidal Molecules and Active Materials

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Fabrication of Multifunctional Particle Clusters

We have developed a new process, called “sequential capillarity-assisted particle assembly” or sCAPA, which harnesses capillary forces acting on a droplet of colloidal particles undergoing controlled drying over a topographical template. By tuning the depth of the traps in the template and the surface tension of the droplet, we are now capable of fabricating colloidal clusters with fully programmable shape and composition, far surpassing the state of the art of other current technologies. The keystone of this work is the realization of a process that allows the sequential, step-wise filling of topographical traps patterned in silicon elastomers. After sequential filling, the particles can be mechanically linked by sintering, harvested from the templates and dispersed in solution. The process does not require specific chemistry for the particles to be deposited and linked, and we have demonstrated the fabrication of a library of multifunctional clusters, also called colloidal molecules, containing organic, oxide and metallic particles.

Schematics of the working principle of sCAPA.  
Schematics of the working principle of sCAPA.

Some examples of the particle clusters that we have realized are reported in the figure below. They include, but are not limited to, organic-inorganic dumbbells, positive-negative dumbbells, magnetic-non magnetic dumbbells, arbitrary particle sequences and multifunctional trimers. These particles open up vast possibilities to study the self-assembly of complex building blocks with applications ranging from lock-and-key recognition, to advanced particle lithography and active manipulation of microscale objects.

Examples of multifunctional particle clusters
Examples of multifunctional particle clusters

Active Materials

We have recently started working on active colloids. More results on this topic coming soon!

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