Figure 8.

(a) Schematic of fabrication process for microchannels made by soft lithography. Injection of a liquid metal in the microchannel makes a liquid metal pattern. Reprinted by permission from Springer Nature: [66], Copyright 2019. (b) Schematic showing the sequential process of vacuum filling liquid metal into a T-shaped microfluidic channel with one inlet but no outlets. A liquid metal droplet is dispensed over the inlet. The whole substrate is placed in a vacuum chamber, which removes the air within the microchannel via the gas permeable elastomer. Releasing the vacuum returns the ambient to atmospheric pressure, which pushes the metal into the microchannel. Reproduced from Ref. [67] with permission from the Royal Society of Chemistry.