Microfluidic devices manipulate small amounts of fluid and have a wide variety of applications, from testing minute blood samples to performing chemical reactions. Ju-Hee So and Michael Dickey, North Carolina State University, USA, have developed a fast, simple way to create microelectrodes for microfluidic devices, by using liquid metal.

The microfluidic devices have three channels. The central channel is separated from the other two by a series of closely set posts. A liquid metal alloy of gallium and indium is injected into the two outer channels. The alloy fills the outer channels, but rapidly and spontaneously forms an oxidized skin that spans the space between the posts – leaving the central channel free to receive other fluids.

The microelectrodes are inherently aligned with the microfluidic channels, are in direct contact with the fluid in the channels, and vertically span the sidewalls of the channel. This allows a uniform electric field to be applied throughout the height of the channel and perpendicular to the direction of flow.

• Inherently aligned microfluidic electrodes composed of liquid metal
  J.-H. So, M. D. Dickey,
  Lab Chip 2011, 11, 905–911.
  DOI: 10.1039/C0LC00501K