Colorful MXene inks for multifunctional textiles

Textiles are the ultimate wearables, providing 24/7 next-to-skin coverage of large areas of our body. They present large surface areas to host sensing devices. Great effort has been made to impart electronic properties - movement tracking, biological signal monitoring and actuation functions for haptic interactions– by incorporating conductive materials into traditional textiles. However, these metal and carbon-based conductive materials not only limit the hues to silver, black and grey but also require a large amount to be deposited for sufficient electrical conductivity – an approach that makes these textiles dull and harsh, deviate from the vibrant and comfortable textiles we love and experience every day. MXenes could pose a solution. MXenes are a family of two-dimensional transition metal carbides and nitrides with the highest electrical conductivity among solution processible nanomaterials. MXenes exhibit distinct colors from green, blue to purple, gold of different shades depending on the transitional metal(s) present (e.g., Ti, V, Nb, Mo, and Cr) and on their structuring. Moreover, the functional groups on the surfaces of MXenes allow them to establish strong interactions with the substrates, making them ideal conductive additives for durability and scale. Here, screen printing—a widely adopted technique in the textile industry—was demonstrated as an economical method for not only faithfully replicating MXene colors and achieving high conductivities on fabrics but also for carefully placing and combining MXenes for many electronic functions.