David Savastano, Editor05.18.11
There are an incredible array of possible applications for printed electronics (PE), and almost as many ways to actually produce PE systems. For textile and other flexible applications, conductive fibers are one potentially successful approach.
Conductive fibers historically have played a role in innovation, dating back to the use of a carbonized sewing thread used as a filament in Thomas Edison's light bulb. This was the first filament that met Edison’s needs for resistance and life span.
Conductive fibers consist of a non-conductive or less conductive substrate, which is then either coated or embedded with electrically conductive elements such as carbon, nickel, copper, gold, silver or titanium. Substrate fibers typically include cotton, polyester, nylon, and stainless steel to high performance fibers such as aramids, HDPE, PBI, PBO, PTFE, carbon nanotubes and others.
These fibers offer some advantages over wires, as they are lighter yet more durable, and can help reach optimum electrical and mechanical performance. There is work underway in both manufacturing and on the university level in fields as diverse as aircraft and space, smart clothing, electromagnetic interference (EFI) shielding and more.
It is reasonable to believe that conductive fibers can be integrated into PE systems. This is one of the key messages of the newly-formed Conductive Fiber Manufacturers Council (CFMC). The CFMC was conceived in 2007 as a result of growth and fragmentation in the industry and too little information being readily available to engineers and designers about conductive fibers and fabrics. After talks with industry leaders, Hugo Trux launched the Council as a trade association in 2011.
“This trade association is a welcome addition to our industry because its inherent fragmentation makes it harder for designers and engineers to find and use our products” said Chris Kneizys, president of Micro-Coax, Pottstown, PA, a charter member of the Council.
Trux, CFMC’s executive director, came out of the conductive fiber industry, and he sees excellent potential for these types of products.
“When I was doing marketing for a conductive fiber manufacturer, I noticed that the engineers I was dealing with weren’t very familiar with the conductive fiber genre, although they knew about individual types of products (like silver thread, carbon thread, Aracon, etc.),” Trux said. “Many were not grasping the full picture of how conductive fibers could solve some application problems, or improve on existing applications. I also noticed there was no clearing house or central place one could go for information about various conductive fibers.
“This lack of exposure is due to the relative newness of the industry as an industry, even though various fibers have been around for a century. In fact, Thomas Edison used a carbon thread as a filament for his working light bulb,” Trux added. “Conductive fibers straddle the field of textiles/fibers, and wire. They belong equally in both worlds, or in neither.”
Trux said that the mission of CFMC is to increase understanding and utilization of conductive fibers and fabrics through information dissemination, advocacy, research and administration of programs to the members' benefit and the advancement of their industries.
Much of the work being done in the field of conductive fibers is on the university level, including MIT, Iowa State University, University of Florida and many others, and promising R&D is also happening in corporations globally.
“There is much promising work going on at the university level,” Trux said. “However, I would venture that there is an equal amount going on in private labs and at the corporate level; however those results only see light at time of patent application.
“Two of the most promising applications include the ability to apply or imbed metals into modern miracle fibers – fibers that offer extraordinary strength, heat resistance, environmental stability, and the potential of manufacturing inexpensive and continuous carbon-nanotubes,” Trux added.
Al Abed, president of I-CLAD Technologies, said he views the CFMC world as consisting of conductive (intrinsically) fibers and conducting fibers.
“Intrinsically conductive fibers are conductive by the very physical and chemical nature of the basic fiber,” Mr. Abed said. “Included in this group are metallic wire, graphite fibers, intrinsically conductive polymer fibers and carbon nanotubes.
“In my opinion, the most promising innovations in this arena involve glassy metal, nanotubes (carbon and otherwise) and some of the advances in intrinsically conductive polymers,” Mr. Abed added. “As the basic physics of conductivity is better understood – a condition which is being impacted greatly by the present emphasis on high-temperature superconductors – new innovation will occur in the intrinsically conductive polymers. In addition, as nanotubes fabrication becomes cheaper, more reliable, and capable of providing longer continuous filaments, I expect to see a blossoming of new innovations, products and applications for these materials.
“Conducting fibers are represented by metal-core or metal-clad fibers and ‘filled’ polymer,” Mr. Abed continued. “This arena is going to be driven primarily by nanotechnology and by the innovative application of existing technologies in unexpected combinations. One arena of new innovation involves nano-material fillers, which provide higher conductivity with lower loading densities. In most cases, these conductivity improvements are accomplished by either more highly conductive nano-particles or by some mechanism for improved connectivity between particles in the polymer matrix.”
Trux and Abel said that there are numerous markets where the advantages of conductive fibers are ideal.
“Key markets are areas where the attributes of fiber (flexibility, lightweight, strength, ability to work with textile machinery) and wire (conductivity, connectability) intersect,” Trux noted. “These markets include shielding and cabling in aircraft, vehicles, portable and worn electronics, EMI shielding, antennas, tethers and medical devices, to name a few.”
“As conductive and conducting fibers improve, both in terms of their current-carrying capacity and their signal transmission capacity, I see major areas where, because of their higher strength, lighter weight, and (ultimately) lower cost, they become drop-in replacements for more conventional wire products,” Abel said. “Aerospace, aviation, automotive, military, and medical applications abound for lighter, stronger, more flexible, higher reliability wire substitutes.
“Supplies of high-demand materials, such as copper, which are presently in short supply, can be ‘extended’ in many cases,” Abel added. “Lightweight replacements for copper wire will become increasingly critical as energy supplies decline and demand increases, especially in ground and air transportation systems. ‘Fuel savings by virtue of weight reduction’ will become a major mantra of the next decade. Count on it.”
Trux sees opportunities ahead for utilizing conductive fibers for printed electronics.
“Carbon and other conductive fibers complement printed electronics,” Trux concluded. “Now they could be used to reduce weight in some kinds of circuits, or increase flexibility. However, I foresee the day when electronics are placed not only on plastic sheets or foils, but onto a conductive fiber. Think of a photovoltaic fiber becoming a photovoltaic vest, or a conductive fiber that acts as a battery.”
|
Photo courtesy of A.MOHR Technische Textilien GmbH. |
Conductive fibers consist of a non-conductive or less conductive substrate, which is then either coated or embedded with electrically conductive elements such as carbon, nickel, copper, gold, silver or titanium. Substrate fibers typically include cotton, polyester, nylon, and stainless steel to high performance fibers such as aramids, HDPE, PBI, PBO, PTFE, carbon nanotubes and others.
These fibers offer some advantages over wires, as they are lighter yet more durable, and can help reach optimum electrical and mechanical performance. There is work underway in both manufacturing and on the university level in fields as diverse as aircraft and space, smart clothing, electromagnetic interference (EFI) shielding and more.
It is reasonable to believe that conductive fibers can be integrated into PE systems. This is one of the key messages of the newly-formed Conductive Fiber Manufacturers Council (CFMC). The CFMC was conceived in 2007 as a result of growth and fragmentation in the industry and too little information being readily available to engineers and designers about conductive fibers and fabrics. After talks with industry leaders, Hugo Trux launched the Council as a trade association in 2011.
“This trade association is a welcome addition to our industry because its inherent fragmentation makes it harder for designers and engineers to find and use our products” said Chris Kneizys, president of Micro-Coax, Pottstown, PA, a charter member of the Council.
Trux, CFMC’s executive director, came out of the conductive fiber industry, and he sees excellent potential for these types of products.
“When I was doing marketing for a conductive fiber manufacturer, I noticed that the engineers I was dealing with weren’t very familiar with the conductive fiber genre, although they knew about individual types of products (like silver thread, carbon thread, Aracon, etc.),” Trux said. “Many were not grasping the full picture of how conductive fibers could solve some application problems, or improve on existing applications. I also noticed there was no clearing house or central place one could go for information about various conductive fibers.
“This lack of exposure is due to the relative newness of the industry as an industry, even though various fibers have been around for a century. In fact, Thomas Edison used a carbon thread as a filament for his working light bulb,” Trux added. “Conductive fibers straddle the field of textiles/fibers, and wire. They belong equally in both worlds, or in neither.”
|
|
Much of the work being done in the field of conductive fibers is on the university level, including MIT, Iowa State University, University of Florida and many others, and promising R&D is also happening in corporations globally.
“There is much promising work going on at the university level,” Trux said. “However, I would venture that there is an equal amount going on in private labs and at the corporate level; however those results only see light at time of patent application.
“Two of the most promising applications include the ability to apply or imbed metals into modern miracle fibers – fibers that offer extraordinary strength, heat resistance, environmental stability, and the potential of manufacturing inexpensive and continuous carbon-nanotubes,” Trux added.
Al Abed, president of I-CLAD Technologies, said he views the CFMC world as consisting of conductive (intrinsically) fibers and conducting fibers.
“Intrinsically conductive fibers are conductive by the very physical and chemical nature of the basic fiber,” Mr. Abed said. “Included in this group are metallic wire, graphite fibers, intrinsically conductive polymer fibers and carbon nanotubes.
“In my opinion, the most promising innovations in this arena involve glassy metal, nanotubes (carbon and otherwise) and some of the advances in intrinsically conductive polymers,” Mr. Abed added. “As the basic physics of conductivity is better understood – a condition which is being impacted greatly by the present emphasis on high-temperature superconductors – new innovation will occur in the intrinsically conductive polymers. In addition, as nanotubes fabrication becomes cheaper, more reliable, and capable of providing longer continuous filaments, I expect to see a blossoming of new innovations, products and applications for these materials.
“Conducting fibers are represented by metal-core or metal-clad fibers and ‘filled’ polymer,” Mr. Abed continued. “This arena is going to be driven primarily by nanotechnology and by the innovative application of existing technologies in unexpected combinations. One arena of new innovation involves nano-material fillers, which provide higher conductivity with lower loading densities. In most cases, these conductivity improvements are accomplished by either more highly conductive nano-particles or by some mechanism for improved connectivity between particles in the polymer matrix.”
Trux and Abel said that there are numerous markets where the advantages of conductive fibers are ideal.
“Key markets are areas where the attributes of fiber (flexibility, lightweight, strength, ability to work with textile machinery) and wire (conductivity, connectability) intersect,” Trux noted. “These markets include shielding and cabling in aircraft, vehicles, portable and worn electronics, EMI shielding, antennas, tethers and medical devices, to name a few.”
“As conductive and conducting fibers improve, both in terms of their current-carrying capacity and their signal transmission capacity, I see major areas where, because of their higher strength, lighter weight, and (ultimately) lower cost, they become drop-in replacements for more conventional wire products,” Abel said. “Aerospace, aviation, automotive, military, and medical applications abound for lighter, stronger, more flexible, higher reliability wire substitutes.
“Supplies of high-demand materials, such as copper, which are presently in short supply, can be ‘extended’ in many cases,” Abel added. “Lightweight replacements for copper wire will become increasingly critical as energy supplies decline and demand increases, especially in ground and air transportation systems. ‘Fuel savings by virtue of weight reduction’ will become a major mantra of the next decade. Count on it.”
Trux sees opportunities ahead for utilizing conductive fibers for printed electronics.
“Carbon and other conductive fibers complement printed electronics,” Trux concluded. “Now they could be used to reduce weight in some kinds of circuits, or increase flexibility. However, I foresee the day when electronics are placed not only on plastic sheets or foils, but onto a conductive fiber. Think of a photovoltaic fiber becoming a photovoltaic vest, or a conductive fiber that acts as a battery.”
