CNT Yarn Capacitive Fabric Touch Sensor

DexMat carbon nanotube yarn is conductive, durable, flexible, and lightweight – so naturally, we are excited about its potential to be used in the emerging field of wearable electronics. Because our yarn can be handled like a textile thread, it can potentially be combined together with textile yarns to make clothing with complex electronic functionality without sacrificing comfort or weight. Additionally, because they have such a high surface area, our CNT yarns are excellent at interfacing electrically with the human body, whether that be through contact with body fluids or through “dry” contact with the skin. This means that they can potentially be used to make smart clothing that monitors the health of the wearer, or tracks movement and muscle contraction.

Capacitive touch sensing is a body-to-machine interfacing technology that is already in widespread use in the modern world, and which has a lot of potential in wearable technology – this type of device can be used to fabricate clothing with built-in buttons or even keyboards which operate with the touch of a finger. A basic description of capacitive touch sensing technology can be found here.

With the help of our friends at ZSK, we have made a capacitive touch sensor using DexMat CNT yarn. Check it out in the video below!

The demo consists of a patch of CNT yarn sewn into the backing fabric, with the tail end of that yarn connected to one of the input pins of an Arduino chip. The Arduino can be connected to a computer or other power source via a usb connection, and this connection provides that chip with a “ground” electrical voltage. Touching the CNT yarn with a fingertip shifts the voltage level of the connected input pin away from that ground level, and this triggers a pre-defined response (in this case, lighting up the Arduino LEDs and playing a sound). This works with a very light touch from the finger, and even works with just the single CNT yarn connecting the swatch to the chip – the additional surface area of the CNT yarn fabric patch wasn’t necessary for this particular case, but it also serves as a nice demonstration of how the yarn can be incorporated into a fabric!

The CNT yarn that was used to make this demo was our 200 micron HS yarn, but other yarn sizes should produce similar results. You can order CNT yarn and fiber in a variety of sizes from our online store at store.dexmat.com.

Wearable Electronics: Carbon Nanotube Yarn + LEDs

This is the follow-up to our previous video, in which we demonstrated how our carbon nanotube yarn could be stitched into fabric using a conventional sewing machine. Here we are showing off the finished product: a DexMat t-shirt with blinking LEDs embedded into our lightning bolt logo!

We used an Arduino Gemma and a small battery pack (sewn into a pouch near the hem of the shirt) to create this LED effect. The electrical connections between the Arduino and the LEDs consist of 4 lengths of our high strength 130 micron carbon nanotube yarn. As Tyson demonstrates, this yarn can easily bend and fold with the shirt, and the zig-zag stitch allows it to stretch as well. It’s also extremely light and comfortable!

Check out the first part of this project here.

DexMat Carbon Nanotube Yarn + Sewing Machine

Here we show the first part of the process of making a simple wearable electronic display in a t-shirt using our carbon nanotube yarn. We use a standard sewing machine to stitch several long filaments of our yarn into the shirt; we plan to eventually connect these to a battery, an Arduino, and some LEDs.

The CNT yarn is strong enough and flexible enough to be run through the sewing machine without being damaged, but it is somewhat less flexible, and much less stretchable, than cotton yarn; as a result we did have some trouble, as you can see in this video. In the end, the carbon nanotube yarn worked well when it was fed from the bottom bobbin. It worked well when fed from the top bobbin and stitched into thick fabric, but not so well with the more elastic t-shirt fabric.

Complications aside, this video demonstrates the potential of our carbon nanotube fibers and yarns for use in e-textiles. It is possible that with more time and knowledge we may have been able to troubleshoot the problem…if you are a wearable electronics maker, why not get some of our yarn and see if you are able to make it work? 🙂

Update: check out our video of the completed shirt here!

Flexible CNT Antennas from Rice U

Antennas of flexible nanotube films an alternative for electronics

HOUSTON – (June 10, 2019) – Antennas made of carbon nanotube films are just as efficient as copper for wireless applications, according to researchers at Rice University’s Brown School of Engineering. They’re also tougher, more flexible and can essentially be painted onto devices.

The Rice lab of chemical and biomolecular engineer Matteo Pasquali tested antennas made of “shear-aligned” nanotube films. The researchers discovered that not only were the conductive films able to match the performance of commonly used copper films, they could also be made thinner to better handle higher frequencies.

Metal-free antennas made of thin, strong, flexible carbon nanotube films are as efficient as common copper antennas, according to a new study by Rice University researchers. (Credit: Jeff Fitlow/Rice University)

Metal-free antennas made of thin, strong, flexible carbon nanotube films are as efficient as common copper antennas, according to a new study by Rice University researchers. (Credit: Jeff Fitlow/Rice University)

The results detailed in Applied Physics Letters advance the lab’s previous work on antennas based on carbon nanotube fibers.

The lab’s shear-aligned antennas were tested at the National Institute of Standards and Technology (NIST) facility in Boulder, Colorado, by lead author Amram Bengio, who carried out the research and wrote the paper while earning his doctorate in Pasquali’s lab. Bengio has since founded a company to further develop the material.

At the target frequencies of 5, 10 and 14 gigahertz, the antennas easily held their own with their metal counterparts, he said. “We were going up to frequencies that aren’t even used in Wi-Fi and Bluetooth networks today, but will be used in the upcoming 5G generation of antennas,” he said.

Bengio noted other researchers have argued nanotube-based antennas and their inherent properties have kept them from adhering to the “classical relationship between radiation efficiency and frequency,” but the Rice experiments with more refined films have proved them wrong, allowing for the one-to-one comparisons.

To make the films, the Rice lab dissolved nanotubes, most of them single-walled and up to 8 microns long, in an acid-based solution. When spread onto a surface, the shear force produced prompts the nanotubes to self-align, a phenomenon the Pasquali lab has applied in other studies.

Bengio said that although gas-phase deposition is widely employed as a batch process for trace deposition of metals, the fluid-phase processing method lends itself to more scalable, continuous antenna manufacturing.

The test films were about the size of a glass slide, and between 1 and 7 microns thick. The nanotubes are held together by strongly attractive van der Waals forces, which gives the material mechanical properties far better than those of copper.

The researchers said the new antennas could be suitable for 5G networks but also for aircraft, especially unmanned aerial vehicles, for which weight is a consideration; as wireless telemetry portals for downhole oil and gas exploration; and for future “internet of things” applications.

Rice University alumnus Amram Bengio holds a flexible nanotube film antenna. The antenna, which has proven as efficient as those made of copper wire, can essentially be painted onto devices. (Credit: Jeff Fitlow/Rice University)
Rice University alumnus Amram Bengio holds a flexible nanotube film antenna. The antenna, which has proven as efficient as those made of copper wire, can essentially be painted onto devices. (Credit: Jeff Fitlow/Rice University)

“There are limits because of the physics of how an electromagnetic wave propagates through space,” Bengio said. “We’re not changing anything in that regard. What we are changing is the fact that the material from which all these antennas will be made is substantially lighter, stronger and more resistant to a wider variety of adverse environmental conditions than copper.”

“This is a great example of how collaboration with national labs greatly expands the reach of university groups,” Pasquali said. “We could never have done this work without the intellectual involvement and experimental capabilities of the NIST team.”

Co-authors of the paper are Rice graduate student Lauren Taylor, research group manager Robert Headrick and alumni Michael King and Peiyu Chen; Damir Senic, Charles Little, John Ladbury, Christian Long, Christopher Holloway, Nathan Orloff and James Booth, all of NIST; and former Rice faculty member Aydin Babakhani, now an associate profess or of electrical and computer engineering at UCLA. Pasquali is the A.J. Hartsook Professor of Chemical and Biomolecular Engineering, professor of chemistry and of materials science and nanoengineering. Bengio is the founder and chief operating officer of Wootz, L.L.C.

The Air Force Office of Scientific Research, the Department of Defense and a National Defense Science and Engineering Graduate Fellowship supported the research.

 

Source: Rice University News & Media

High strength 130 micron CNT yarn spotlight

In this video we focus on one of our newly available products, a higher strength version of our 130 micron diameter carbon nanotube yarn.

New Carbon Nanotube Film Product Release

In this video we introduce 10 micron thick film to the catalog of DexMat film products and show how the film can be easily processed on standard winding equipment. CNT films have tremendous potential in applications ranging from EMI shielding in cables/electronics, to thermal interface materials, to heating elements or conductive materials in clothing or e-textiles. High conductivity, high strength, 10 micron thick film is now available for purchase at the DexMat online store!

Braiding CNT Fibers

In this video, we demonstrate the process that we use for braiding carbon nanotube fibers to make EMI shielding braids or braided CNT yarns. These braids are lightweight and highly flexible. They are also more conductive than stainless steel fiber braids and much stronger than copper wire.

Carbon Nanotube Tapes up to 5 cm wide!

This video demonstrates the array of carbon nanotube tapes that DexMat currently produces. Strong, conductive, and flexible tapes or films up to 5 cm wide are currently available and even wider tape formats are currently under development.

These tapes have tremendous potential in applications ranging from EMI shielding in cables/electronics, to thermal interface materials, to heating elements or conductive materials in clothing or e-textiles.

Making Carbon Nanotube Yarns

This video shows how carbon nanotube (CNT) fibers can be assembled into yarns or ropes by plying the fibers together with a planetary ropemaking machine. These yarns are lightweight and highly flexible. They are also more conductive than stainless steel thread and much stronger than copper wire.

DexMat at IDTechEx, Santa Clara, 2018

Last month we had the opportunity to show off our carbon nanotube yarns and films at the IdTechEx conference in Santa Clara, CA. In this video, Dmitri describes the various materials and applications that we spoke about at our booth. It was a great show, and we are excited to return to other IdTechEx events in the future!