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Optoelectronics

Cavendish Laboratory, Cambridge

Studying at Cambridge

 

Tom O'Neill

Tom O'Neill

PhD student in the Eiser Group.


Email:
Office Phone: +44 (0)1223 337040

Research Interests

I'm a second year PhD student working with Dr Eiser in Physics and Dr Vignolini in Chemistry and funded by the EPSRC NanoDTC. The aim of my research is to synthesise gels with novel optical properties that emulate those that give rise to structural colour in nature.

We synthesise colloids, primarily polystyrene, and functionalise them with DNA through various chemistries. DNA-coated colloids are an excellent system to use for self-assembly, as inter-particle interactions are normally repulsive, but include a strong, tuneable, thermally reversible and specific attraction through the hybridisation of complementary strands of DNA.

When we bring a suspension of such particles below their melt temperature, they phase separate into a network of colloid-rich branches and a continuous medium of colloid-poor pores; a gel. We aim to use annealing of these structures and the assembly of non-spherical particles to moved beyond simple diffusion-limited gels and create those with photonic properties.

 

Figure: (top left) SEM image of PS (polystyrene) colloids dried in a thin film. (top right) Aqueous suspension of the freshly polymerised and cleaned PS particles. (bottom left) large dried colloidal film of the same colloids. Under a specific Bragg angle the film shows intense blue, structural colour. Otherwise it appears white. (bottom right) Schematic of Bragg reflections from a colloidal crystal.