Advances in electronic textiles and smart clothing are poised to revolutionize everything from life-saving medical wearables to smart athletic shirts—and carbon nanotube (CNT) fibers and yarn could be the connective thread that ties all that possibility together.
DexMat’s conductive, durable, flexible, and lightweight Galvorn material supports a cornucopia of transformative use cases. Here, we’ll explore its role as an electrically conductive thread or conductive fabric for e-textiles—that is, any fabric or piece of clothing that has some electrical function. This kind of “smart clothing” has a huge range of uses: it might consist of clothing with heating or cooling elements to keep the wearer comfortable in extreme temperatures; it might read electric signals from the wearer’s body to monitor heart rate or other health metrics; it might be used to monitor muscle strain and performance for athletes. This new wave of technology will be game-changing for everyday consumers, and it will be critically important for soldiers and first-responders, giving their uniforms and equipment new ways to keep them safe and monitor their health.
Conductive threads that can be sewn into fabric or woven together are one of the main components of e-textiles and wearable electronics. Before we dive into how Galvorn is suited for e-textiles, let’s start with what materials the industry has used historically.
Traditional Materials for Electronic Textiles
Every major e-textile material candidate has its unique strengths and weaknesses. Let’s dig in to the top three non-CNT materials:
Stainless Steel Thread
Pros: Stranded stainless steel yarns perform well as conductive threads due to their high strength and durability; steel is durable enough to be worked into thin, flexible filaments without breaking. It provides good conductivity because the entire thread is made of conductive metal, making it a popular choice for incorporating battery-powered devices into clothing. Stranded thread made of pure copper or silver might provide more conductivity but would be far less durable and more prone to oxidation.
Cons: The primary drawbacks of stainless steel thread are weight and stiffness; this type of material wouldn’t be comfortable worn against the skin, and any garment with stainless steel threads worked into it will tend to be a little less flexible than a garment made with a different e-textile material.
Metal-coated Textile Threads
Pros: A hybrid of metal and textile thread can be made by coating textile thread or flexible polymer thread with a layer of highly conductive metal like nickel or silver. This produces threads and fabrics that have a highly conductive outer skin, yet retain the strength, flexibility, and approximate density of the underlying textile. As an added benefit, the metallic skin of these threads allows them to be soldered to other metallic parts to support electrical connection. Overall metallized fabric provides a good combination of both electrical conductivity and comfort against the skin, because it can flex and stretch like a regular textile.
Cons: However, durability can be an issue for these threads, since the metallic layers can de-bond and begin to peel away from the textile substrate. Additionally, when these thin metal layers oxidize or tarnish, their conductivity can decrease dramatically. For clothing in particular, this means long-term wear with regular laundering will decrease the fabric’s electrical performance over time.
Conductive inks are composed of small conductive particles (for example, silver nanoparticles) that can be mixed into a liquid medium and sprayed or printed onto conventional textiles to form an electrically conductive layer. This is somewhat similar to the metal coatings discussed above, but does not form a solid metallic surface layer. Conductive inks represent a way to turn any textile material into an e-textile—with some limitations.
Pros: Conductive ink can be added to existing textiles or fully-formed pieces of clothing, so it can keep some of the performance and feel of the underlying textile. The main advantages to this technique are that it is suitable for very fast and inexpensive mass-production, and it is relatively easy to apply the conductive pathways in whatever pattern is desired on the backing fabric.
Cons: Conductive ink is fast to apply to fabric, but depending on the structure and texture of the fabric it might not work well. The ink may soak into fabric and spread out too much to be useful, rather than remaining in a concentrated layer. Even if it does form a concentrated layer it is not typically very durable: it might survive some laundering, but loses conductivity over time through repeated washing, and movement of the underlying fabric can cause it to crack or flake away.
A few polymers possess the intrinsic ability to conduct electricity. The flexibility of polymer materials and the fact that they can be processed in liquid form make these materials extremely useful for creating flexible electronic components of various shapes. For wearable e-textile applications, conventional textile thread like silk can be coated with a conductive polymer layer to gain some electrical conductivity while keeping the strength and flexibility of the underlying thread.
Pros: On the plus side in e-textiles, conductive polymers can help create smooth, flat conductive patches on the surface of a conventional textile, so it can be useful in creating conformal contact with skin in order to pick up electric signals from the body. They can also be mixed with various other materials or dopants to best suit particular applications, and can be made into semiconductors as well as conductors. What’s more: unlike metal wire or metalized fabric, polymer materials won’t oxidize, so they won’t degrade after repeated exposure to moisture or laundering.
Cons: That said, two main drawbacks exist when it comes to using conductive polymers in e-textiles. First, their conductivity is typically much lower than that of metals (although sufficient alignment and doping can increase it to a level that exceeds stainless steel, as in the case of stretch-oriented polyacetylene).
Second, it isn’t extremely easy to connect them to metal contacts, such as signal wires or wires from a battery; metal and polymer parts cannot be soldered together, and conductive polymers are sometimes too brittle to be crimped without damaging them.
Hybrid conductive threads, in which textile thread is coated with conductive polymer or with a metal layer, exist to preserve the mechanical properties and light weight of conventional thread for maximum comfort and ease of construction in wearable e-textiles. Stainless steel thread exists to maximize conductivity while minimizing oxidation and corrosion impacts. Conductive polymers allow the creation of relatively comfortable clothing patches that are not highly conductive, but that aren’t vulnerable to oxidation or corrosion from repeated washing.
Galvorn carbon nanotube fibers, yarns, and fabrics are soft, durable, conductive, and carbon-negative at scale
Galvorn provides the full suite of material properties valued in e-textile applications.
From a mechanical standpoint, Galvorn is less similar to metal wire and more like textile fibers, in that it boasts excellent tensile strength, flexibility, and fatigue life, on top of being lightweight. Galvorn fibers can also be made in a wide range of sizes, helping achieve the right fabric-like consistency. For example, small fibers can be used to make conductive connections that are extremely unobtrusive and flexible, or to achieve a softer fabric feel.
At the same time, Galvorn’s conductivity is similar to metals, even exceeding that of stainless steel thread. While silver and nickel have higher conductivity than Galvorn, they are typically incorporated into conductive thread in the form of a thin coating over an insulating filament core, resulting in a lower overall conductivity. And Galvorn is even more resistant to oxidation than stainless steel, so it can maintain conductivity for a long time, perhaps indefinitely, through laundering and daily use.
Finally, with the textile industry under pressure to improve its carbon footprint, Galvorn stands out in yet another category—sustainability—thanks to its recyclability and potential to be carbon negative at scale.
We’ve already developed a few simple e-textile projects for inspiration, including this LED-lit smart shirt and a CNT yarn capacitive touch sensor that could help companies fabricate clothing with built-in buttons or even keyboards that operate with the touch of a finger.
The future of e-textiles is adaptive and sustainable
The scope of possibility is sky-high for using Galvorn CNT fibers, yarn, and fabrics in e-textile applications when powered by imagination and ingenuity. For instance, Galvorn can be coated with layers of metal, a process that further enhances conductivity, while also making it possible to solder onto other metallic electrical components. This could be useful for wearable devices that require e-textile threads to have a good connection to battery power, such as heating elements in a shirt, socks, or gloves.
Already, DexMat has used Galvorn to produce prototype versions of a game-changing category of smart clothing: an EKG monitoring vest. With funding from the Advanced Functional Fabrics of America, DexMat partnered with Hexoskin Health Sensors & AI to make and test prototypes of the Hexoskin vest using Galvorn electrodes to pick up the wearer’s heartbeat.
These examples only scratch the surface for how e-textiles and wearable electronics companies can leverage Galvorn. Ready to explore the vast potential for your own applications? Step one: Shop our soft, durable, conductive CNT yarn offerings today or feel free to contact us and share the challenges you’re facing in e-textile product development and let’s discuss if Galvorn can help.