Meet the MXene-Coated “Faraday” Fabric Capable of Blocking EMI in Wearable DevicesDecember 24, 2020 by Luke James
Researchers at Drexel University have reported an MXene-coated "Faraday fabric" that can block almost all electromagnetic waves, providing a lightweight option for blocking EMI in wearable devices.
There’s no denying the vital role that electromagnetic waves play in our modern digital world. But, as more devices come into use, interference is becoming problematic for some applications like wearable devices.
Research recently published in the journal CARBON demonstrated the utility of a conductive, two-dimensional material called MXene in providing electromagnetic interference (EMI) for wearable and mobile devices.
Why Does EMI Shielding Matter for Wearables?
Yury Gogotsi, Ph.D., lead for the Drexel University-based research team, discussed in a press release how necessary it is becoming to integrate EMI protection into clothing to shield wearable devices. This need becomes more pressing as wearable devices become more common and needed in daily life.
EMI can destabilize important connections, leading to a slow down and loss of the electronic devices’ function. In consumer-grade devices, this can be irritating. In medical-grade devices, this could be dangerous.
EMI coupling modes. Figure courtesy of Aviti Mushi.
Since MXene can be coated on fabrics, it marks a key development in potentially safely weaving technological capabilities such as sensors and RF circuitry into clothing.
Drexel's news department referred to this MXene-coated fabric as a "Faraday fabric" in reference to the famous Faraday cage, first demonstrated by Michael Faraday, which blocks electromagnetic fields in an enclosure by wrapping it in conductive materials.
MXenes vs. Traditional Shielding
To protect electronic devices from EMI, important components are usually wrapped in a shielding material such as copper or foil. However, these shielding materials can add weight and bulk to devices, which is difficult for applications where size and space are a premium, such as implantable and wearable electronics. These shielding materials also do nothing to reduce ambient noise because they only reflect incoming waves.
MXenes are a type of two-dimensional carbide and nitride compounds that are highly conductive and hold high potential for applications like faster battery-charging electrodes. Though the EMI-blocking capabilities of MXene were known before the Drexel team's research, the study demonstrates the idea that it can efficiently adhere to fabrics and keep its shielding attributes.
MXene coated fabric was found to be 99.9% effective at blocking EMI. Screen capture used courtesy of Drexel University.
Gogotsi and colleagues have been working with titanium carbonitride, a type of MXene, to create a material capable of protecting against electromagnetic radiation. In recently published findings, the researchers describe a thin, few-atoms-thick material that absorbs waves rather than reflecting them.
Drexel's MXene Connectivity Experiment
Gogotsi, who has been working with MXenes for almost a decade, believes that MXenes are applicable for use as shielding EMI. This is because MXenes can be stably developed as a spray coating, allowing them to be applied to textiles without adding weight or taking up space.
In the video below, a researcher shows two phones connecting on a call and then one being wrapped in MXene-coated fabric. The signal for the following call is blocked by the MXene and shown to be unable to connect.
In this study, the researchers dip-coated regular cotton and linen fabrics in an MXene solution. They found that this turns the fabric into a shielding material, blocking EMI with 99.9% effectiveness. MXene flakes suspended in solution adhere to cotton and linen fibers because of their electrical charge. This produces a thorough durable coating without the need for other pre/post-treatment processes.
Longevity for Shielding Applications
The MXene-coated fabrics were tested after being stored under normal conditions for two years and still demonstrated high shielding efficiency that only dropped slightly by 8% to 13%.
Shielding efficiency over a two-year span. Image courtesy of Yury Gogotsi et al. and Drexel University.
In addition to shielding against EMI, the new wave-blocking fabrics may also help in building protective suits for people who need to enter environments with dangerously-high levels of electromagnetic fields. With this innovation of EMI blocking fabric, the adaptations can be numerous.
Featured screen capture used courtesy of Drexel University.