Flexible and Stretchable Liquid Metal Electrodes Working at Sub-Zero Temperature and Their Applications

Area of Science:

• Materials Science
• Electrical Engineering
• Nanotechnology

Background:

• Flexible and stretchable electronics require robust electrode materials.
• Liquid metals offer unique conductive properties but face challenges in stability and patterning.
• Developing efficient solar-blind photodetectors is crucial for UV detection applications.

Purpose of the Study:

• To investigate the characteristics of Galinstan electrodes under various conditions, including sub-zero temperatures.
• To demonstrate solar-blind photodetection using the spontaneous oxidation of Galinstan.
• To develop a simple and rapid fabrication method for patterned, flexible, and stretchable Galinstan electrodes.

Main Methods:

• Fabrication of flexible and stretchable Galinstan electrodes via compression of microdroplets on flexible substrates.
• High-resolution patterning of Galinstan films using a laser marking machine (20 μm resolution).
• Characterization of electrical conductivity under stretching (up to 130%) and sub-zero temperatures.
• Exfoliation of surface gallium oxide (Ga2O3) layers using elastomeric stamps.
• Fabrication and testing of solar-blind photodetectors by combining Galinstan electrodes and their oxide layers.

Main Results:

• Achieved electrical conductivity of ~1.3 × 10^6 S m^-1 for the Galinstan electrodes.
• Electrodes maintained electrical conductivity even at 130% stretching below 0 °C.
• Successfully fabricated solar-blind photodetectors on flexible substrates.
• Photodetectors showed a 14.7% increase in output current under deep UV irradiation (254 nm) at low intensity (0.1 mW cm^-2), with no response to visible light.

Conclusions:

• Galinstan is a promising material for highly flexible and stretchable electrodes, even in sub-zero environments.
• The spontaneous surface oxide layer of Galinstan can be utilized for effective solar-blind photodetection.
• The developed fabrication method is simple, rapid, and scalable for producing patterned Galinstan electrodes for advanced electronic applications.