Liquid Metal Enables Flexible Devices That Harvest the Body’s Energy

Achievement date: 

Liquid metal that’s used to connect standard, bulk electronic components promises to make flexible devices that harvest a body’s thermoelectric energy as efficient as rigid predecessors, according to research conducted at North Carolina State University and the Engineering Research Center (ERC) for Advanced Self-Powered Systems of Integrated Sensors and Technologies (ASSIST), based at the school and funded by the NSF.


Making flexible devices that can tap into the human body as an energy source is crucial to developing wearable, long-lasting sensors that can monitor someone’s health and surrounding environment. The innovative use of a liquid metal of gallium and indium in a common, non-toxic alloy allows the use of electronic component “legs” that already manufactured in bulk while maintaining the device’s flexibility. 


The performance and efficiency of flexible devices in harvesting energy have paled in comparison to rigid devices, which have been superior in their ability to convert body heat into usable energy. Yet, it’s difficult with the rigid devices to maintain a consistent connection to the skin where they harvest energy. The use of the liquid alloy comes after disappointing results from other approaches to flexible devices, such as thin-film deposition techniques, that suffered from greater thermal or electrical resistances. The liquid alloy allows the legs of a series of standard thermoelectric devices to be connected, promising lower-cost components while providing stretchable connections that can heal themselves from breaks.