Invisible Shield for Electromagnetic Interference

Scientists from Bengaluru’s Centre for Nano and Soft Matter Sciences (CeNS) have created a transparent shield for electromagnetic interference by fabricating a metal mesh structure instead of a continuous coating on desired transparent substrates (EMI). Metal meshes are used to create these transparent and flexible EMI shields, which are manufactured utilising a crack templating approach through spray painting that was developed in their lab.

Transparent shield for electromagnetic interference

Optoelectronic devices in visual windows require transparent electromagnetic interference (EMI) shielding materials with excellent optical transparency and superior shielding efficiency (SE). 

We show how to make a transparent EMI shielding film out of silver nanowires (Ag NWs) using a simple Mayer-rod coating process. Treatment with NaBH4 and polymer lamination can considerably increase the electrical conductivity and transmittance of Ag NW-based films (diallyldimethyl-ammonium chloride). 

The polymer coating reduces surface roughness while causing no harm to the Ag NWs’ uniform mesh. The sheet resistance of the Ag NW/PDDA composite films is 22 sq1 with a transmittance of 95.5 percent, which is superior to that of commercial indium tin oxide (ITO).

Interference Electromagnetic

• EMI is an electromagnetic emission that disrupts the operation of another electrical device.

• EMI may affect any device that contains an electrical circuit.

• It impairs the functioning of electrical devices by blocking and degrading data, and in certain cases, totally erasing data.

• EMI affects a wide range of electromagnetic frequencies, including radio and microwave frequencies.

• The International Special Committee on Radio Interference (CISPR) was established in 1933 to address growing EMI issues.

Important Points

• Metal Mesh Structure: Instead of continuous film, the scientists constructed a copper metal mesh on a PET sheet that has a visual transmittance of roughly 85%.

• The amount of light that travels through a sample is called transmittance. It is light that has not been absorbed, dispersed, or reflected. It’s commonly expressed as a percentage.

• Metal mesh networks on the substrate are more transparent than continuous film because they only cover 7% of the substrate compared to continuous film’s 100% coverage.

• When compared to the same thickness of the continuous metal sheet, which might sacrifice transparency, metal mesh provides greater electromagnetic shielding.

Benefits

The EMI shield’s primary function is to separate a device’s energy so that it does not interfere with other devices and to prevent external energy from entering.

Electronics would not perform as intended without shielding, and they may even cease operating.

This ‘invisible’ shield may be employed in a variety of military stealth applications, covering electromagnetic wave emitter or absorber components without sacrificing aesthetics.

Metal Mesh is Superior to Continuous Metal Film

Touch screen panels (TSPs), flexible and wearable displays, sensors, and actuators all benefit from transparent conducting electrode film.

Indium tin oxide (ITO) sputtered film with high transparency (90%) and low sheet resistance (50/cm2) However, because to the trade-off between high transmittance and low sheet resistance qualities, ITO films lack mechanical flexibility, especially under bending stress, and are limited in their applicability to large-area TSPs (over 15 inches).

Touch screen panels, organic light-emitting light-emitting diode (OLED), and wearable displays, sensors, & actuators all benefit from transparent conducting electrode film.

Various manufacturing processes have been developed to employ metal nanoparticles for conducting electrodes. Using hexanediol self-assembled monolayer (SAM)-protected gold nanoparticles using a polydimethylsiloxane (PDMS) mould, one-step direct nanoimprinting of gold nanoparticles was described.

Trench Layer Patterning and Metal Mesh Mold

The photolithographic and electroplating methods were used to create the embossed metal mesh mould. The engraved trench layer pattern was created by first coating optical grade polyethylene terephthalate (PET) with a photosensitive UV resin, then pressing with the embossed metal mould (less than 10 psi), UV exposure (150 mJ), and demolding.

Electromagnetic wave emitter or absorber devices

Metamaterials, which are defined as materials that do not exist in nature, are artificial materials that provide invisible characteristics in nature, such as negative refraction, perfect absorption, and perfect transmission, by arranging meta-atoms in a periodic pattern with a size 1/3–1/5 smaller than the incident electromagnetic wavelength. Metamaterials may be used in a variety of industries, including perfect lenses, optical cloaking, and microwave antennas, due to their unique properties.

Since the introduction of the metamaterial absorber as a plane form patterned by copper on a dielectric substrate, numerous study results for matching electromagnetic wave properties by changing the shape and type of metal pattern and dielectric layer have been reported: Metamaterial made of gold that shows transparent changes in THz range due to magnetic field changes, metamaterial made of gold that shows polarisation direction changes of electromagnetic waves at 1.4 THz, metamaterial made of gold quantum dot that can change frequency absorbed due to electric field direction changes, metamaterial made of gold that shows improvement in resistive heat loss in solar generation.

Conclusion

The simplest method for removing magnetically induced interference is to use twisted pair wires. This is true for both shielded and unshielded cables, as well as shield currents and other sources of interference. By creating a metal mesh structure instead of a continuous coating on desirable transparent substrates, scientists from Bengaluru’s Centre for Nano and Soft Matter Sciences (CeNS) have constructed a transparent barrier for electromagnetic interference (EMI). Metal meshes are employed to make these transparent and flexible EMI shields, which are made using a crack templating method created in their lab using spray painting.