Liquid metals: Iron-on circuit; thermal drawing of e-fibers; recyclable, self-healing circuits; ‘living metal’ bioelectronics.
Researchers from Virginia Tech developed iron-on electronic circuits that can be applied to clothing. The patch uses electrically conductive liquid metal and a heat-activated adhesive to bond to fabric when heated with a hot iron.
“E-textiles and wearable electronics can enable diverse applications from health care and environmental monitoring to robotics and human-machine interfaces. Our work advances this exciting area by creating iron-on soft electronics that can be rapidly and robustly integrated into a wide range of fabrics,” said Michael D. Bartlett, a researcher at Virginia Tech, in a statement.
The device uses droplets of gallium-indium alloy added into a polyurethane mixture, which was then poured into a thin layer. After air-drying for a day, it formed a soft, electrically conductive elastic sheet. The team then ironed small rectangular pieces of the sheets onto various fabrics, including plain weave polyester, cotton twill, knit spandex, and mesh jersey. The polymer in the conductive patches created strong bonds with the fibers, keeping the layers together once they cooled.
To demonstrate the iron-on circuit, the researchers created a square of fabric with LEDs that remained lit when repeatedly folded, twisted and stretched. They also created a stretchable wire microphone inside a shirt, with the ironed-on circuit relaying power and audio signal underneath the garment and out to an external recording device. The ironed-on microphone recorded sound across the full human hearing range with performance comparable to a traditional microphone setup. [1]
Researchers from École polytechnique fédérale de Lausanne (EPFL) used a technique called thermal drawing, traditionally used to engineer fiber optics, to process liquid metals into electronic fibers that combine high and stable conductivity with stretchability.
“We have integrated thermal drawing into a greatly simplified process for producing fiber sensors with finely tailored electronic properties, making them promising candidates for smart textiles for sport and health monitoring applications,” said Fabien Sorin, head of the Laboratory of Photonic Materials and Fiber Devices (FIMAP) in EPFL’s School of Engineering, in a press release.
The process starts with creating a macroscopic version of the electronic fiber called a preform, which contains liquid metal components arranged in a 3D pattern. The preform is then heated and stretched out to make fibers a few hundred microns to millimeters in diameter that retain the same 3D pattern. The pattern allows for control of which areas of an individual fiber are electrically conductive or insulating.
“When the liquid metal is mixed with a soft elastomer matrix, it forms many small droplets. The process of heating and stretching the preform breaks these droplets and activates the liquid metal. This means that we can finely tune the functionality of a single fiber by controlling which areas become active through the shear stress caused by the preform stretching process,” explained Stella Laperrousaz, a PhD student at EPFL, in a press release.
In tests, the fibers remained highly sensitive even when stretched to over 10 times their original length. The technique was used to build a smart knee brace that can monitor a user’s movements and joint function during activity. [2]
Researchers from the University of Washington and Oak Ridge National Laboratory created a flexible, self-healing, and recyclable material that acts like a circuit board using a liquid metal composite.
Made from a recyclable vitrimer polymer infused with microscopic droplets of a liquid metal alloy based on gallium, the composite material is soft and stretchable. A circuit can be created on the composite by lightly scoring a pattern into its surface, which connects adjacent embedded droplets and allows electricity to flow. The rest of the material remains electrically insulating.
Additionally, the material can be broken down through a simple chemical process. In experiments, researchers recovered 94% of the metal from their samples. Its self-healing properties enable it to be cut into pieces and rearranged, then bonded back together with just heat and pressure to create a new configuration. [3]
Researchers from Binghamton University created liquid “living metal” bioelectronic composites by combining gallium-indium liquid metal droplets with dormant endospores of the electrogenic bacteria Bacillus subtilis.
“When we combine the spores with the liquid metal droplets, there is a huge attractive force, because the spores have chemical functional groups on their surface that interact with the liquid metal oxide layers. This strong force ruptures the oxide layers so the metal can be conductive,” said Seokheun “Sean” Choi, a professor in the Department of Electrical and Computer Engineering at Binghamton University.
The spores can stay inactive under harsh conditions, and the composite is easily absorbed into device substrates such as paper while keeping the best properties of metal. When the spores germinate, it exhibits enhanced electrical conductivity. Additionally, the composite shows self-healing capabilities.
The researchers noted that more experimentation is needed to better control the activation of the endospores and to evaluate the liquid living metal composites for long-term stability. [4]
[1] J. Joyce, B. T. Wilcox, A. Ingram, and M. D. Bartlett. Iron-On Wearable Electronics through Liquid Metal Adhesive Composites. ACS Applied Materials & Interfaces 2025 17 (46), 63764-63774 http://dx.doi.org/10.1021/acsami.5c13752
[2] S. Laperrousaz, X. Chen, M. Cleusix, et al. Electronic fibres via the thermal drawing of liquid-metal-embedded elastomers. Nat Electron 8, 1072–1081 (2025). https://doi.org/10.1038/s41928-025-01485-0
[3] Y. Han, S. S. Rohewal, S. Gupta, et al. Conductive Liquid Metal Vitrimer Composites for Reconfigurable and Recyclable Flexible Electronics. Adv. Funct. Mater. (2025): e11119. https://doi.org/10.1002/adfm.202511119
[4] M. Rezaie, Y. Gao, and S. Choi. Living Liquid Metal Composites Embedded with Electrogenic Endospores for Next-Generation Bioelectronics. Adv. Funct. Mater. (2025): e21818. https://doi.org/10.1002/adfm.202521818
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