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Optoelectronics

Cavendish Laboratory, Cambridge

Studying at Cambridge

 

Alessio Caciagli

Alessio Caciagli

PhD student in the Eiser Group


Email:
Office Phone: +44 (0)1223 768146

Research Interests

I am PhD student and Fellow of the European Training Network COLLDENSE. My project is on developing DNA-functionalized droplets for ‘template free microfluidics’. 

In this context I study the self-assembly of colloids anchored to water-oil interfaces via DNA. I perform both, experimental studies and simulations. We recently published some of the work (D. Joshi, D. Bargteil, A. Caciagli, J. Burelbach, Z. Xing, A. S. Nunes,  D. E. P. Pinto,  N. A. M. Araujo,  J. Bruijc, E. Eiser ‘Kinetic control of the coverage of oil droplets by DNA-functionalised colloids’, Science Advances, 2 : e1600881 (2016)).

 

Figure: Left: Cartoon of a colloidal particle optically trapped at the surface of an oil droplet. The DNA provides the anchoring to the oil-water interface, but the colloids are still mobile.The optical trap (by means of an optical tweezer) creates an external potential profile which attracts the particles to the trap center and induces a rich colloidal dynamics at the liquid-liquid interface. a) Energy profile probed by a single colloid confined to the oil droplet surface, for different trap strenghts G. The profile is reconstructed from the motion of the particle observed through an optical microscope. The optical trap generates a gentle potential, which is approximately harmonic. The particle is free to explore the potential well while remaining anchored at the liquid-liquid interface, thus displaying a quasi-2D motion. b) Optically-induced crystallization of colloids on the oil droplet surface. The attractive potential generated by the trap is able to drag many surface-anchored colloids to the trap center. Since the induced forces are weak (on the order of a pN) the colloids can rearrange and minimize the global energy, forming an hexagonal close-packed structure.