Network topologies dictate electromechanical coupling in liquid metal-elastomer composites

Area of Science:

• Materials Science
• Composite Materials
• Nanotechnology

Background:

• Elastomers with liquid metal (LM) fillers offer unique properties compared to rigid fillers.
• Liquid metal droplets can form conductive networks in elastomers, enabling electromechanical coupling.
• Experimental data shows minimal resistance increase in liquid metal-embedded elastomers (LMEEs) during stretching, contradicting classical predictions.

Purpose of the Study:

• To computationally analyze the electromechanical properties of conductive LMEE composites.
• To understand the relationship between liquid metal droplet morphology and electrical resistance changes during stretching.
• To rationalize experimental observations of stable resistance in stretched LMEEs.

Main Methods:

• Computational analysis of conductive LMEE composites.
• Examination of the influence of pathway tortuosity on electromechanical coupling.
• Development of a dimensionless parameter to estimate gauge factor based on path tortuosity.

Main Results:

• The gauge factor (G), quantifying electromechanical coupling, decreases as the tortuosity of conductive pathways increases.
• A dimensionless parameter for path tortuosity can effectively estimate G in statistically homogeneous LMEE composites.
• The findings provide a mechanistic explanation for the observed stable electrical resistance in stretched LMEEs.

Conclusions:

• The assembly and tortuosity of liquid metal droplet networks significantly influence the electromechanical functionality of LMEEs.
• Computational insights rationalize experimental observations and highlight the importance of microstructure in LMEE performance.
• This work offers a pathway for designing LMEEs with tailored electromechanical responses for advanced applications.