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Dynamics of Droplets of Biological Fluids


In Biomedical and Bioengineering fields, the successful implementation of lab-on-chip devices for biochemical analysis offers a significant reduction of samples and reagents, as well as faster analysis, given the smaller diffusion distances, which also allow a more efficient control of the reactions.


In this context, the transport and manipulation of biological samples inside liquid droplets under electrostatic actuation offers great potential for the development of these micro-devices, but requires devising biocompatible interfaces with particular wetting characteristics.

Regarding the surface properties, different approaches have been addressed: (i) hydrophobic surfaces based on regular surface micro-patterning, (ii) hydrophobic surfaces, in which the hydrophobicity is mainly changed at the expense of altering the chemistry of the surface and (iii) biomimetic approach considering biomimetic hierarchical micro-patterning and/or surface chemistry modification.


In the last the emphasis has been given to biomimetics of leafs and petals with hierarchical structure, which can be accurately replicated by inexpensive methods. In this context, high adhesion surfaces were obtained from biomimetics of rose petals, while low adhesion surfaces are mimicked from English weed leaves.

Wettability Characterization on Complex Surfaces


The success of electrowetting - induced transport of proteins strongly depends on the local wettability as this is affected by the prompt and irreversible adsorption of the biomolecules.


The wettability is usually characterized by macroscopic quantities, which are often limited by the spatial resolution of the available diagnostic techniques and cannot be accurately related to the multiscale phenomena occurring at the interfaces. A more accurate approach is the Laser Scanning Confocal Microscopy with fluorescent droplet which allows 3D reconstruction of the droplet by stacking 2D optical sections collected in series of well-defined z-steps.


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