Nanofabrication for all-soft and high-density electronic devices based on liquid metal

Abstract

Innovations in soft material synthesis and fabrication technologies have led to the development of integrated soft electronic devices. Such soft devices offer opportunities to interact with biological cells, mimicking their soft environment. However, existing fabrication technologies cannot create the submicron-scale, soft transducers needed for healthcare and medical applications involving single cells. This work presents a nanofabrication strategy to create submicron-scale, all-soft electronic devices based on eutectic gallium-indium alloy (EGaIn) using a hybrid method utilizing electron-beam lithography and soft lithography. The hybrid lithography process is applied to a biphasic structure, comprising a metallic adhesion layer coated with EGaIn, to create soft nano/microstructures embedded in elastomeric materials. Submicron-scale EGaIn thin-film patterning with feature sizes as small as 180 nm and 1 μm line spacing was achieved, resulting in the highest resolution EGaIn patterning technique to date. The resulting soft and stretchable EGaIn patterns offer a currently unrivaled combination of resolution, electrical conductivity, and electronic/wiring density.

Stand‐Alone Intrinsically Stretchable Electronic Device Platform Powered by Stretchable Rechargeable Battery

“…[53,54] The LM is not disconnected even under extremely large strains (ε > 800%), [55] thus an LM circuit line does not suffer the resistance change even when the line width is very narrow (≈10 µm). [56,57] However, they need conductive passivation to acquire long-term stability and reliable contact with metal pads. On the other hand, the polymer composite conductors can have stable contacts with metal pads, but their electrical resistance under stretching becomes unstable as the pattern width decreases down to ≈100 µm because the conduction paths are limited in the width direction.…”

Pervasive liquid metal printed electronics: From concept incubation to industry

“…Such technology makes the direct preparation of electronic devices no longer an unattainable goal. Until now, researchers have already been able to directly produce themselves antennas ( Lin et al., 2015 ), RFID tag ( Gao et al., 2016 ), capacitors ( Gao et al., 2013 ), and many more other devices ( Kim et al., 2020 ). Therefore, it can be seen that LMPE is opening a huge application space, especially in personalized electronic circuit manufacturing.…”

Facile and Rapid Method for Fabricating Liquid Metal Electrodes with Highly Precise Patterns via One‐Step Coating

“…[ 21–25 ] However, it is difficult to fabricate patterned electrodes of the desired shape with resolutions suitable for electronic applications using gallium‐based liquid metals, due to their high surface tension and rapid oxidation in air. [ 26,27 ] Thus, various patterning techniques, such as direct writing, [ 28,29 ] microcontact printing, [ 30 ] microfluidic injection, [ 31–34 ] laser ablation, [ 35,36 ] imprint lithography, [ 37 ] and stencil lithography, [ 38 ] have been proposed to overcome these major drawbacks. These techniques have significant potential; however, depending on the method, the demanding process conditions or the low patterning resolution limits (i.e., tens to hundreds of micrometers) still need to be improved for enabling practical electronic applications.…”