A method inspired by spider silk spinning has led to the development of soft fibres that are not only strong, stretchable, and electrically conductive but also can be easily reused.
The innovative fabrication process, pioneered by a team of researchers led by Assistant Professor Swee-Ching Tan from the Department of Materials Science and Engineering at the National University of Singapore’s College of Design and Engineering, opens up possibilities for a wide range of smart textile applications.
Creating fibres with all three desired properties has been a complex and challenging task. Conventional methods require high pressure, extensive energy input, large amounts of chemicals, and specialized equipment, resulting in fibres with limited functionalities. Taking cues from spiders’ natural silk spinning process, the team sought to emulate the efficient and versatile characteristics of spider silk formation.
The researchers identified two crucial steps in spider silk production that they could mimic. First, they observed that protein concentration and interactions increase during silk dope formation and spinning. The second step involves liquid-solid phase separation, where proteins rearrange within the dope triggered by external factors, separating the liquid portion from the solid spider silk fibres.
By recreating these two steps, the team introduced the phase separation-enabled ambient (PSEA) spinning approach. They used a gel solution called PANSion, consisting of polyacrylonitrile (PAN) and silver ions dissolved in dimethylformamide (DMF), a commonly used solvent. Under ambient conditions, the gel solution is pulled and spun, forming soft fibres. As the gel is exposed to air, water molecules act as a trigger, causing the liquid portion to separate into droplets from the solid part. Gravity facilitates the removal of the liquid droplets, leaving behind the solid fibres.
This innovative spinning process successfully produced soft fibres that possess the desired properties of strength, stretchability, and electrical conductivity. Stress tests confirmed the remarkable mechanical strength and elasticity of the PANSion gel, attributed to strong chemical networks formed by metal-based complexes within the gel. Molecular-level analysis confirmed the electrical conductivity of the fibres, thanks to the presence of silver ions.
The versatility of the PANSion soft fibres was demonstrated through various applications. They were sewn into an interactive glove that functioned as a smart gaming glove, detecting hand gestures to enable user engagement in simple games. The fibres also showed potential for communication applications, such as transmitting Morse code through changes in electrical signals. Additionally, they were capable of sensing temperature changes, offering potential protection for robots in extreme environments. The researchers even incorporated the fibres into a smart face mask that monitored the wearer’s breathing activity.
In addition to their wide-ranging applications, the PANSion soft fibres offer sustainability benefits. They can be recycled by dissolving them in DMF, allowing for the creation of new fibres. Compared to current fibre-spinning methods, this spider-inspired approach consumes significantly less energy and requires fewer chemicals.
Moving forward, the research team will focus on enhancing the sustainability of the PANSion soft fibres throughout their entire production cycle, from raw materials to recycling the final product. This groundbreaking discovery paves the way for a new era of wearable technology, offering tremendous potential for advancements in smart textiles.
