Blocking Radiation in Wearable Devices

Researchers use scanning electron microscopy (SEM) to characterize a lightweight, flexible material with high performance shielding capabilities

From wearable fitness trackers, such as smartwatches, to wearable healthcare devices, such as ECG and blood pressure monitors, there is a rising demand for increasingly advanced wearable devices. Devices such as these are packed with highly integrated circuits, which generate electromagnetic radiation. As such, there is a need for high performance, electromagnetic interference (EMI) shielding materials that are both lightweight and flexible.

Dr. Yongwen Tan and his research group at Hunan University, China, have published an article presenting a method for fabricating light-weight, foldable, and highly stable MXene foams. MXene foams are 2D transition metal carbides and/or nitrides with metallic conductivity that have shown promise for EMI shielding. Dr. Tan provided us with some insights into his publication and use of scanning electron microscopy (SEM) for characterization of these foams.

Dr. Yongwen Tan and his colleagues preparing samples.

You use scanning electron microscopy (SEM) as one of your tools to characterize the MXene foam. SEM shows it to be porous in nature. Can you explain the significance of this?

First, designing porous structures can make the material lightweight. As mentioned above, being lightweight is an important technical requirement for practical electromagnetic interference (EMI) shielding applications. More importantly, introducing the porous structure can also improve the EMI shielding performances of the material by facilitating the internal dissipation of the terahertz waves and lead to less surface reflection to avoid secondary electromagnetic pollution.

Cross-sectional scanning electron microscopy (SEM) image showing the porous nature of the MXene-based foam.

You also use scanning electron microscopy (SEM) to show that the MXene foams you generated have excellent flexibility and rubber-like folding behaviors. Can you elaborate on why these features are of interest?

Being flexible is another important technical requirement for EMI shielding materials. To this day, many porous EMI shielding materials have been reported but very few of them can present desirable EMI shielding performances and outstanding flexibility simultaneously. Moreover, being flexible is also very needed for materials to be used in other applications, such as supercapacitors and batteries. In our work, we realized the excellent flexibility and rubber-like folding behaviors of the porous MXene material by designing the unique oriented cellular structure which not only provides insight on designing high-performance EMI shielding materials but can also expand the applications of MXene materials in 3D macroscopic form.

Scanning electron microscopy image showing the flexibility of the MXene based foam.

You show that different metals can be used to generate freestanding MXene foams that contain diļ¬€erent metal species according to the same protocol. Why is this important?

The multivalent metal species in the foam act as crosslinking sites for connecting the MXene nanosheets to form a stable porous structure. By presenting that different metals can be used to generate freestanding MXene materials, we wish to show the controllability and versatility of the fabrication method and demonstrate the possibilities of the MXene foams for applications where different metal species are needed for improving the performances.

Learn More

Read the full article “Highly Stable 3D Ti3C2Tx MXene-Based Foam Architectures toward High-Performance Terahertz Radiation Shielding

Find more information on ZEISS Scanning Electron Microscopes.

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