Researchers at Carnegie Mellon University have developed a material that exhibits a unique combination of high electrical and thermal conductivity with actuation capabilities that are unlike any other soft composite. Advances in the fields of soft robotics, wearable technologies, and human/machine interfaces require such new class of stretchable materials that can change shape adaptively while relying only on portable electronics for power.
Thermally Conductive and Intelligent Material
It is not only thermally and electrically conductive, it is also intelligent,” said Carmel Majidi, an associate professor of mechanical engineering who directs the Soft Machines Lab at Carnegie Mellon. “Just like a human recoil when touching something hot or sharp, the material senses, processes, and responds to its environment without any external hardware. Because it has neural-like electrical pathways, it is one step closer to artificial nervous tissue.”
New Technique Combined with LCEs
This is the first time that Majidi’s lab has combined this technique with liquid crystal elastomers (LCEs), a type of shape-morphing rubber.
LCEs are like liquid crystals used in flat-panel displays but linked together like rubber. Because they move when they are exposed to heat, they hold promising functionality as a shape-morphing material.
Unfortunately, they lack the electrical and thermal conductivity needed for shape memory activation. Although rigid fillers can be incorporated to enhance conductivity, these cause the mechanical properties and the shape-morphing capabilities of LCEs to degrade. The researchers overcame these challenges by combining the liquid metal gallium indium with the LCEs to create a soft, stretchable composite with unprecedented multifunctionality.
Damage Response – One Step Ahead
Another key feature of the material is its resilience and response to significant damage.
“We observed both electrical self-healing and damage detection capabilities for this composite, but the damage detection went one step further than previous liquid metal composites,” explained Michael Ford, a postdoctoral research associate in the Soft Machines Lab and the lead author of the study. “Since the damage creates new conductive traces that can activate shape-morphing, the composite uniquely responds to damage.”
Many High-end Applications
The material’s high electrical conductivity allows the composite to interface with traditional electronics, respond dynamically to touch, and change shape reversibly. It could be used in any application that requires stretchable electronics like:
- Wearable computing
- Assistance devices
- Space travel