Carbon nanotube yarn taps nerves for electroceutical treatments and diagnostics

(Nanowerk News) Ingested or injected pharmaceuticals can target specific molecules involved in disease processes, but get distributed throughout the body where they can cause unwanted side effects. An approach known as electroceuticals aims to avoid systemic exposure by using small wires to electrically monitor and manipulate individual nerves that control organ function and carry information about disease. Despite the promise of electroceuticals, it has been challenging to develop long-term therapies due to the lack of biocompatible wires.
Now, NIBIB-funded researches have spun carbon nanotubes into flexible, nerve-sized wires or yarns capable of high-fidelity long-term connections in live animals. The development of these biocompatible yarns opens the possibility of new bioelectric diagnostics and therapies through regulation of internal organ function at the single nerve level.
Individual carbon nanotubes are pulled from a substrate and spun into the flexible carbon nanotube yarn
Individual carbon nanotubes are pulled from a substrate and spun into the flexible carbon nanotube yarn. (© NPG)
All the organs of the body such as the heart, lungs, liver, and kidneys are automatically controlled by nerves that stretch from the brainstem to each organ. These nerves control organ functions such as heartbeat, breathing rates, and blood pressure, making constant adjustments in response to environmental and physiological changes. Variations in the electrical activity in this area of the brain, known as the autonomic nervous system, can also be predictors, indicators or causes of disease development.
“Monitoring and manipulating the autonomic nervous system to both understand and potentially treat disease has been an intriguing yet understudied approach to medicine,” explains Michael Wolfson, Ph.D., director of the NIBIB program in Rehabilitation Engineering and Implantable Medical Devices. “This is largely due to technical limitations in being able to insert wires into nerves that can reliably and safely record electrical activity over long periods of time and under different physiological conditions.”
In a study reported in the journal Scientific Reports (“Chronic interfacing with the autonomic nervous system using carbon nanotube (CNT) yarn electrodes”), bioengineers at Case Western Reserve University in Cleveland, Ohio describe the development of highly flexible carbon nanotube (CNT) yarn electrodes that were capable of months-long electrical recording in major nerves of the autonomic nervous system in rats.
The CNT yarns are essentially, just that, yarns made from a “forest” of hundreds of carbon nanotubes that are pulled from the metal surface they are grown on and spun into a highly flexible, highly conductive wire 1/100th the size of a human hair.
carbon nanotube yarn is wound around a tungsten needle for insertion into a nerve
The carbon nanotube yarn is wound around a tungsten needle for insertion into a nerve. The coiling of the yarn causes it to remain solidly embedded in the nerve after the needle is withdrawn. Actual needle and yarn (top). Diagram showing detail of how yarn is wrapped around the needle for insertion (bottom). (© NPG)
Current technologies for recording electrical signals from nerves include relatively large stiff tungsten needles used by neurologists to obtain readings from single nerves of patients for several hours, but must be removed before causing lasting nerve damage. Other wire electrode technologies can record nerve signals for short periods but because of their dimensions and stiff mechanical properties they are not suitable for long-term recording in small nerves.
“The currently available electrode technologies simply do not match the mechanical properties of nerves,” explains Dominique Durand, Ph.D., Professor of Biomedical Engineering at Case Western and senior researcher on the CNT yarn work. “With those types of electrodes, it’s often like sticking glass into spaghetti. Our CNT yarns are similar in size and flexibility to actual nerves. These properties allow them to be stealthily inserted into specific nerves and remain there for months without destroying the tissue or inducing an attack by the immune system.”
The combination of the biocompatibility of the CNT yarns and their outstanding ability to carry an electrical signal that is 10 times stronger than current technologies makes them ideal for long term recording of specific nerve signals. Finally, the lack of nerve damage keeps the surrounding axons intact, which helps to eliminate background noise. Thus, the CNT yarns have an excellent signal to noise ratio (SNR), which is critical for this type of research.
The group tested the CNT yarns in two major nerves in the autonomic system in rats. One study involved the vagus nerve, which stretches throughout the body to connect to numerous organs. The nerve is known to control and monitor a range of functions including heart rate, digestive tract movement, sweating, and immune response.
CNT yarn electrodes were also inserted into the glossopharyngeal nerve. The nerve is connected to a number of organs including the carotid artery, and parts of the ear, tongue and salivary glands where it is known to be involved in swallowing.
Carbon nanotube yarn embedded into the vagus nerve of a rat
Carbon nanotube yarn embedded into the vagus nerve of a rat. (© NPG)
In both nerves, recordings of stable electrical activity were maintained over a 10-week period. Pulses of nerve activity were also monitored while the animal responded to physiological challenges. The challenges included distension of the rat’s stomach with saline solution, and short durations where the rats were in low oxygen environments. In each case, the physiological changes induced by the challenge resulted in easily detectable changes in electrical activity that were recorded using the CNT yarn implants over the entire 10-week period of the experiments.
“Although this is early research, we believe the results demonstrate that this technology can be used for reliable long term electrical monitoring of physiological functions,” says Durand. “This is an important step in pursuing monitoring of disease progression through the nerves that control the function of the diseased organ.”
Durand explains that the goal is to learn what electrical signatures or profiles are indicative of disease development and to use that for early intervention, potentially by electrical stimulation or even blocking of the nerve. For example, one therapy for severe hypertension is the cutting of the renal nerve. This is obviously irreversible. Durand, explained that CNT yarn electrodes could be used to block the nerve impulse without cutting the nerve, making the treatment reversible.
The group is also excited about the potential of this recording method to improve prosthetics. “When an arm has been amputated there are tens of thousands of neurons remaining,” said Durand. “The approach would be to insert the CNT yarns into individual nerves and record the electrical signals that are created as the individual thinks about moving the missing arm—essentially learning the electrical signals that are formed by the intention to move the arm.” The ultimate goal is to develop neural interfaces capable of translating those electrical signals into better control of the prosthetic by the user.
Source: National Institute of Biomedical Imaging and Bioengineering

Physics Charge Smartphones Clothes Made From Carbon Nanotubes

Physicists from the University of Cincinnati will soon be able to charge smartphones using clothes made from carbon nanotubes. With the assistance of their colleagues from the BBC, Wright-Patterson, the experts intend to create a special material, which because of the peculiarities of carbon nanotubes would be exceptionally heat-resistant conducting electricity, and will also differ for their durability. Professor mark Schultz, is also involved in the study declared that the task of scientists is to use the resistance and conductivity for energy storage, which can charge a variety of gadgets.

Schulz said that at the moment the science is on the verge of a “carbon revolution,” as this material may soon completely replace metals because of its strength, low weight and various additional properties. Yarns made from nanotubes can store energy, replacing bulky batteries, which soon altogether sink into oblivion.

Full Article: https://sivtelegram.media/physics-charge-smartphones-clothes-made-from-carbon-nanotubes/30672/

Mil-Aero Industries Eye Carbon Nanotubes as They Target Cost Savings

Ultra-lightweight carbon nanotubes may replace copper wires.

Today’s aerospace and aircraft industries focus on size, weight, power, and cost (SWaP-C), and cost is now often figured for program or operational life, which may total thousands of dollars per pound. This gives tremendous impetus and justification to accept high-cost new technology to obtain weight savings.

Reducing F-35 by 20 Pounds Could Provide $230M Savings

Satellites have always paid extra to reduce weight since each payload pound may cost more than $5,000 to launch. Studies by the Center for Strategic and Budgetary Assessments (CSBA) show that the new F-35 has a $4,500 cost per pound over the aircraft’s operational program life

until 2070. (For comparison, the cost per pound for the F-22 is estimated at $3,500.) The F-35 has projected production of2,557 aircraft for the U.S. and nine for export customers scheduled through 2037. Therefore, a weight reduction of just 20lbs per plane could result in savings of $230,000,000! Even if this is off by 50%, the expected benefits already are driving new industry developments.

In addition to fighter aircraft, each ounce is also critical in future soldier wearables, UAVs, portable radars, vehicle communications, and other equipment to increase survivability, mission endurance, and success.

Interconnect weight savings are being obtained by incorporating higher contact density, composite materials, combinational multi-port connectors, and other approaches. However, a new technology involving carbon nanotubes (CNTs) is emerging and offers a lightweight alternative to copper wire and other conductive shielding materials. A carbon nanotube is produced as a layer of carbon atoms in a tubular configuration, in single- or multiple-walled versions.

CNTs are being mixed with polymers to create high-strength, lightweight composite materials. CNT fibers can be made into conductive sheets and tapes, which offer a myriad of potentials. Optimal performance may result from spinning CNT fibers into conductive threads (referred to as yarn) to potentially replace copper wires in harnesses, motor windings, and shields.

Another important gain is reliability. CNT fibers and yarn can withstand millions of bending cycles, while standard fiber/wire would have yielded many times. The minimum bending radius requirements of today’s cable is not applicable for CNT fibers and cables.

Market potentials for CNT technology are bringing new companies into the forefront. Nanocomp Technologies offers commercial CNT fibers created using a carbon vapor deposition (CVD) reactor and then formed into sheets or fibers that can be twisted into shields or primary conductors. Another supplier is Syscom Advanced Materials Inc., which provides a variety of metal-clad fibers.

DexMat Inc. in Houston produces CNT fiber using a wet acid process that draws multiple fibers that can be shaped into a shield or primary conductor, and future developments for  include flat tape. The company boasts a strong Ph.D. cadre from nearby Rice University where they have successfully fabricated coaxial cable inner and outer conductors by coating a solution of CNTs in chlorosulfonic acid to achieve a two-times better conductivity than seen previously. This may prove an attractive alternative to commercial coax cable using tin-coated-copper with comparable attenuation and greater mechanical durability with 97% reduced mass, according to the company.

Usually, the outer conductor is the heaviest portion of today’s cables. In coax, the outer conductor provides both signal transmission and electromagnetic shielding. While shielding does not require high conductivity in the outer conductor, signal loss (i.e., signal attenuation) through the transmission line is significantly affected by the conductivity and architecture of the outer conductor. The new solution-coated CNT outer conductors offer near-term application potentials. Several connector companies are reportedly studying termination techniques.

Carbon Nanotube Materials Provide Shielding

TE Connectivity has been working to use CNT materials for shielding and data transmission cables. In a paper presented at the 2012 IWCS Conference, Dr. Stefanie Harvey, senior manager for corporate strategy, reported that they had achieved greater than 50dB shielding effectiveness in the GHz range, and their “data transmission cables using a yarn format perform comparably to MIL-STD-1553.” In the January 5, 2016 issue of ASSEMBLY, Dr. Harvey reviewed how replacing the braid in RG-58 cable would reduce weight from 38.8 grams per meter (g/m) to 11.5g/m, while replacing the center conductor with CNT yarn would further reduce weight to 7.3g/m for a combined weight reduction of 80%.

Composites are used to replace heavy copper wire with metal plated aramid fibers for use in wire and cable EMI shielding. EMI shielding made with plated aramid fibers can reduce weight by as much as 80%, leading to major weight reduction depending on the size of the aircraft or satellite. Aramid fibers are a class of strong, heat-resistant synthetic fibers, the best known of which is DuPont™ Kevlar®, used in ballistic-rated body armor.

Carlisle Interconnect Technologies (formerly Micro-Coax Inc.) provides a unique weight-reducing EMI/RFI shielding solution using their proprietary high-strength ARACON® brand metal clad fibers. Ron Souders, technical director, Carlisle Interconnect Technologies, advises that, for typical applications, switching to ARACON allows a weight savings of 80% when compared to traditional metal braided or woven EMI shielding products. This offers the conductivity of an outer metal coating with the strength, light weight, and flexibility of aramid fiber.

*Note: DexMat also provides products for shielding applications not mentioned in this article.

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Ron Souders further explained that the specific gravity of aramid fiber is only 1.44g/cc, compared to copper at 8.9g/cc, and that, even with the addition of metal coatings, the specific gravity of ARACON fibers ranges from 3 – 5g/cc. The tensile strength (measured in kilopounds per square inch, or Ksi) of the aramid core (350Ksi) is from three to 10 times higher than that of traditional or high-strength copper cores, which typically span 35 to 95Ksi. Since ARACON fibers behave like a textile, they are far more flexible and compliant than metal.

Industry Standardization is Underway

The benefits offered by CNT fiber, whether as EMI/RFI shielding, signal or coaxial cable, or other new components, have prompted the Naval Air Systems Command (NAVAIR) in Patuxent River, Maryland, to sponsor the establishment of suitable “Military Specification for Conductive Carbon Conductors used in Aircraft Wiring,” eventually with QPL sources. The proposed formal qualification program should stabilize components and materials for future use.

CNT technology also was included in a recent multiple-day RF coordination meeting held in February by the Defense Logistics Agency (DLA) at the Defense Supply Center Columbus (DSCC). Suppliers of basic CNT materials, wire, cables, cable assembles, and signal and RF/microwave connectors are now working on both application-specific and generalized products to achieve the weight reduction and reliability benefits offered by CNT and other metallized fibers.

Original story by David Shaff – April 28, 2017

DexMat Awarded Phase II SBIR – Lightweight CNT Shielded Cables for Space Applications

Abstract: The effects of electromagnetic interactions in electrical systems are of growing concern due to the increasing susceptibility of system components to electromagnetic interference (EMI), use of automated electronic systems, and pollution of the electromagnetic environment with electromagnetic emissions. The effects of EMI can be detrimental to electronic systems utilized in space missions; even small EMI issues can lead to total mission failure, resulting in significant mission delays and economic loss. Additionally, NASA is challenged to find ways of effectively shielding sensitive electronic equipment from EMI without adding significant weight to space flight vehicles and satellites in order to manage fuel costs. The solution for both issues resides in the use of carbon nanotubes (CNTs), which offer the most promising solution for reducing spacecraft wire weight. CNTs are an alluring alternative to conventional conductors used in coaxial data cables because they combine mechanical strength, electrical conductivity, and low density. DexMat has developed a novel CNT deposition process for directly applying CNTs onto dielectric materials to produce an electrically conductive EMI shield. By placing a premium on the quality of raw CNTs, DexMat has created a product with increased potential to reduce cable weight while minimizing insertion losses when incorporated into wire. In the proposed research, DexMat seeks to develop a small-scale CNT Tape production process and continue the development of the CNT separation processes. The need for CNT Tape was discovered while obtaining feedback from potential customers that noted the desire for a product format that allows for quick and easy integration into existing manufacturing processes without the need for outsourcing processes.

Project Details: https://www.sbir.gov/sbirsearch/detail/1426213

DexMat Awarded Phase II SBIR: High Temperature Electric Wires

Abstract: Electric wires and cables constitute by far the largest weight portion of aircraft electrical power systems, as well as a large fraction of the entire aircraft weight. For example, a modern transport aircraft contains over 200 miles of wire, and an F-22 aircraft has about 20 miles of wiring. The increased emphasis and reliance on fly-by-wire technology and avionics for modern aircraft has resulted in wiring becoming a critical safety-of-flight system. Aerospace vehicles continue to increase in wire system complexity and volume as traditional mechanical systems, such as flight controls and flight surface control actuators, are converted to all electric systems. This Phase II Proposal involves a dual pronged strategy for developing high temperature CNT-based power cables: 1) Dexmat will seek to improve the underlying CNT yarn conductivity with and without dopants that do not require encapsulation (i.e., non-transitory dopants); 2) Improve the encapsulation process to enable the use of dopants that do require encapsulation.

Project Details: https://www.sbir.gov/sbirsearch/detail/1488599

DexMat Awarded Phase I SBIR: High-Temperature Electric Wires

Abstract: Electric wires and cables constitute by far the largest weight portion of aircraft electrical power systems, as well as a large fraction of the entire aircraft weight. For example, a modern transport aircraft contains over 200 miles of wire, and an F-22 aircraft has about 20 miles of wiring. The increased emphasis and reliance on fly-by-wire technology and avionics for modern aircraft has resulted in wiring becoming a critical safety-of-flight system. Aerospace vehicles continue to increase in wire system complexity and volume as traditional mechanical systems, such as flight controls and flight surface control actuators, are converted to all electric systems. DexMat is developing a technology for coating doped carbon nanotubes (CNTs) with impermeable barrier films. Under this Phase I project, DexMat will adapt the use of metallic barrier film coatings to prevent the egression of CNT dopants and, thus, preserve high electrical conductivity even if the fiber is subjected to high-temperature environments.; BENEFIT: The proposed primary production of DexMat technology is directed to the commercial and military aviation segments, mainly companies seeking to reduce the weight of their aircraft design. Beyond these customers, the potential uses of CNT wires and films include a broad spectrum of military and civilian applicationsfrom lightweight aerospace cables, to power and data conduits for wearable electronics, to health monitoring and diagnostic sensors.

Project Details: https://www.sbir.gov/sbirsearch/detail/1410755

DexMat Awarded Phase I SBIR: High Conductivity CNT Wiring for High Speed Data Cables

Abstract: In an era of reduced Defense budgets and increasing threats, military planners are seeking new technologies to reduce operating costs and increase operation capabilities for space and aviation platforms, and weight reduction is an attractive target. For example, transportation costs to geosynchronous orbits using a NASA reusable launch vehicle are close to $10,000 per pound of payload. Copper wiring, which makes up as much as one-third of the weight of a 15-ton satellite and 20 miles of an F-22 aircraft, is a clear target for weight reduction. Half of this wire weight is typically in the EMI shielding. Developing new lightweight, conductive materials that replace copper in the shielding and core conductor could serve as a lead candidate for radically reducing this weight. Carbon nanotubes (CNTs) combine high strength, electrical and thermal conductivity with low density, which makes them ideal for applications where weight reduction is a priority. DexMat is commercializing CNT technology that has shown the highest published values for conductivity and mechanical strength of CNT materials. This Phase I Proposal will examine the feasibility of developing CNT-based cables with solution-processing technology capable of producing high performance CNT fibers and coatings, without the use of binders and wetting agents.BENEFIT:The potential benefits of this innovation could include military development for future ground, air or space systems that have stringent weight requirements, including launch vehicles, UAVs, portable communications,small satellites,etc. Commercial Application: Any commercial development for electronic-heavy systems with stringent weight requirements, including jetliners, satellites, small computers, etc.

Project Details: https://www.sbir.gov/sbirsearch/detail/824749