Electroactive Self-Assembled-Monolayer for Smart Functional Surfaces

Self-assembled monolayers (SAMs) bearing a redox active terminal group on conducting surfaces can be interconverted between different states by the application of an external electrochemical stimulus. The high interest toward... [ view full abstract ]

Self-assembled monolayers (SAMs) bearing a redox active terminal group on conducting surfaces can be interconverted between different states by the application of an external electrochemical stimulus. The high interest toward these systems is justified by the possibility to have a high control over the properties of the surface, that can be electrochemically tuned. For instance, the surface wettability strongly depends on the charge or the polarizability of the terminal groups. ¹

Here, a switchable ITO electrode coated with an anthraquinone-derivative (AQ) SAM is reported. A significant modulation of surface wettability yielded a change in surface contact angle as high as 25°. Furthermore, arrays of planar electrodes for droplets actuation were fabricated and integrated in a microfluidic device. We proved the possibility to induce directional movement of water droplets on the substrate to perform operations of mixing and separation on sub-nananoliter scale.

Compared with the typical configuration of electrowetting-on-dielectric (EWOD), ² our system operates at very low voltages (≤ 2.8 V) and, furthermore, it is biocompatible. Cells can be successfully transported on the surface without affecting its viability.

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