Marangoni stress-driven droplet manipulation on smart polymers for ultra-low voltage digital microfluidics

Abstract

An ultra-low voltage microfluidic device for manipulating droplets of liquid by inducing Marangoni stress therein includes a plurality of smart-polymer electrodes having films of smart polymer exposed at their surfaces. The surface of the smart polymer becomes hydrophobic or hydrophilic in response to different electromagnetic potentials. The smart polymer is reversibly oxidized by applying an electrical potential such that the smart polymer acquires a positive electrical charge. The oxidized smart polymer is reduced by applying an electrical potential such that it loses its positive electrical charge. The smart polymer is doped with a chemical compound having a negatively-charged end and a long-chain hydrophobic tail. The smart polymer is a polypyrrole and the dopant is a dodecylbenzene sulfonate. The microfluidic device includes a plurality of individually-addressable control electrodes, each of which is electrically-connected with smart-polymer electrodes. Droplets are transported, cut, or mixed by selectively applying electrical potential to individual electrodes.

Description

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AI Technical Summary

Benefits of technology

The present invention describes how to manipulate small drops of liquid using special materials called smart-polymers. These smart-polymers have certain properties that make them suitable for this purpose. When an electric field is applied to these materials, they form a layer at their surface which affects the way liquids behave when placed on top of them. This allows for easy movement of drops around the surfaces without sticking. Additionally, if two different types of voltage are used, the material becomes either more or less attractive towards water, allowing for mixing of drops or cutting larger ones into smaller parts. Overall, this technology offers new ways to control and move fluids in very precise manners.

Problems solved by technology

The technical problem addressed in this patent text is the requirement for higher driving voltages (15-80V) when using electrostatic actuation methods to manipulate liquid droplets in digital microfluidic circuits. This limits their use in portable and fast diagnostics applications that demand low power consumption. Additionally, the high electric fields used may lead to electrolysis issues in some cases. There is also an interest in developing laboratory-on-a-chip devices that operate at lower voltages, like the ones available from standard battery cells.

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