Researchers from the National University of Singapore jointly with their colleagues from the University of Southampton in the UK and the University of New South Wales in Australia have developed smart textiles that are tolerant to stretching and can adapt to external conditions. This solution addresses some of the key problems of wearable electronics: signal distortion and energy losses during movement. When a conductor is stretched, its resistance usually increases, which not only weakens the signal but also leads to additional energy losses. With the new material, this behavior can be modified in advance: when deformed, the fabric can either maintain stable conductivity or even improve it depending on the mode selected.
The innovation is based on a liquid metal, the eutectic alloy of gallium and indium, which remains fluid at room temperature. The scientists mixed microscopic droplets of the metal with elastic polyurethane and formed it into a core-shell fabric using a coaxial wet-spinning method. The outer layer of polyurethane insulates the conductive core, preventing leaks and providing mechanical strength. The resulting thread is similar in its properties to conventional yarn: it can be bent, knotted and sewn into fabric using standard methods.
The scientists’ key discovery is that the mechanical behavior of the fabric can be modified by pre-stretching. If the fabric is pre-stretched by about 50%, its resistance will drop with further deformation, improving energy transfer efficiency. If stretched further (up to 150%), its resistance will increase, as with conventional conductors. At intermediate values, the material becomes virtually insensitive to stretching: its resistance changes by less than 1.2% even when stretched twice as much. This is critical for energy applications, where parameter stability has a direct impact on losses. This effect is achieved because during stretching droplets of liquid metal begin to contact more closely, and their protective oxide film ruptures, allowing the droplets to merge and create increasingly branched conductive paths.
The researchers not only recorded this effect but also described it mathematically. They proposed a model that relates resistance to the magnitude of deformation, the proportion of liquid metal and the mechanical parameters of the material. It takes into account two competing mechanisms: conductivity improvement caused by particle contact and fusion versus conductivity degradation due to geometric elongation. The model closely matches experiments and makes it possible to calculate fabric properties in advance, including those related to energy efficiency.
The scientists demonstrated three practical applications of this technology.
In one case, device control using motion was demonstrated. Two fibers with different responses to stretching were used: one conducting current less efficiently when bent and the other conducting it more efficiently. When a person bends a finger, both fibers respond differently, and the system registers this as a simple digital signal, such as “0” or “1”. The movement is essentially converted into binary code, which can be used to control devices or transmit commands without complex signal processing.
In another application, the fibers were used to transmit energy and data. The fiber was adjusted so that its properties would remain virtually unchanged when stretched, minimizing energy loss. The material can be used to make textile antennas by sewing them into clothing. In an experiment, a textile antenna reliably transmitted a signal to a smartphone when stretched up to 60%, after washing and at high humidity. This means that clothing can serve not only as a communication interface but also as an element of the distributed energy infrastructure of wearable devices.
Finally, the material has proven useful for heating purposes. In conventional warming clothing, resistance changes with stretching, which results in uneven temperature distribution and reduced energy efficiency. With the new threads, this effect was eliminated: the fabric’s properties remained stable, which meant stable energy consumption and evenly distributed heating regardless of user movement.
In addition, experiments demonstrated the durability of the new material: it withstood more than 10,000 stretching cycles without loss of properties, which makes it suitable for long-term use in energy and wearable systems.
