1. Light-Directed Particle Patterning by Evaporative Optical Marangoni Assembly
S.N. Varanakkottu+, M. Anyfantakis+, M. Morel, S. Rudiuk and D. Baigl*
Nano Lett. 2015, DOI: 10.1021/acs.nanolett.5b04377

2. Light-Driven Transport of a Liquid Marble with and against Surface Flows
N. Kavokine, M. Anyfantakis, M. Morel, S. Rudiuk, T. Bickel and D. Baigl*
Angew. Chem. Int. Ed. Eng. 201655, 11183

Light-Driven Microfluidic Applications

Can we move a drop sitting on a solid surface by shining light on it? Can we optically control wettability alterations and exploit them for optofluidic tasks? Can we pattern colloids at predefined positions on the surface? Well, at least we try!

We are generally interested in exploring the coupling between light and the behavior of simple and complex liquids.

Part of our current research focuses on the application of optical fields for controlling the wetting properties of sessile droplets sitting on photoresponsive surfaces. Our goal is to exploit assymetric wetting for inducing macroscopic drop motion. The possibility of moving drops simply by irradiating them could be the starting point for performing various optofluidic operations with drops, in open (not channel-based) configurations.

Another route for manipulating liquids externally by using light stimulus, is to optically control the hydrodynamic effects taking place in liquids. In particular, we are currently exploring the application of light patterns for the controlled assembly of particles at predefined positions in drying colloidal dispersion drops. 

Combined with liquid evaporation, the optically engineered flows can be harnessed for programmable particle patterning from drying drops. Such an example is shown in the figure below, where a 4-spot light pattern created by a simple, LED-based optical setup (a) was applied to a drying drop containing polystyrene particles. The formation of 4 (material) spots containing accumulated particles could be observed using brightfield (b) and fluorescent (c) microscopy, after evaporation.