Human health and electromagnetic radiation: The role of knitted yarns,fabrics,and garments

Abstract

The usage of electronic devices connected with Wi-Fi has raised several concerns regarding electromagnetic pollution. Prolonged exposure to electromagnetic radiation has been associated with adverse effects on human health. Reported health issues include increased risk of anxiety, depression, sleep disturbances, and infertility. Protection against these harmful effects is essential, and textiles offer a promising solution. Since textile fabrics are in direct contact with the human body for extended periods, they must be soft, flexible, and non-toxic to ensure comfort and safety. The use of advanced conductive fibers can effectively attenuate harmful electromagnetic radiation. The aim of this review is to examine the impact of low-frequency electromagnetic radiation on human health and to explore the potential role of advance fibers and knitted fabrics in attenuating such radiation. This study also investigates the health issues associated with long-term exposure to low frequency range electromagnetic radiation. Various end use applications of knitted electromagnetic shielded fabrics, along with the materials used in their structures, were studied. Key parameters, as well as the machinery used in their production, were analyzed. The literature indicates that knitted fabrics hold significant potential for electromagnetic shielding applications due to their breathability, flexibility, elasticity, and the ability to control loop.

Keywords

Health fibers textile electromagnetic shielding knitted garments

Introduction

Theoretical background

Knitting is the second most popular method of fabric manufacturing after weaving.¹ The knitwear market was globally USD 894.06 billion in 2024.^2–6 Production of knitted fabrics requires less labor and has the shortest production cycle as compared to other fabric manufacturing techniques. In knitting technology, material wastage is minimal as compared to weaving. Knitting allows for a greater range of structural formation as compared to weaving. Despite potential drawbacks like a loose structure, and poor dimensional stability, knitted fabrics can be optimized by adjusting loop sizes, making them suitable for various technical applications such as filtration and electromagnetic shielding.

Technical knitting refers to the application of knitting techniques and technologies for the development of fabrics with specific functional or technical properties. These technical textiles are designed to meet specific requirements of various industries such as healthcare, sports, military, automotive, and aerospace. Electromagnetic-shielding knitted fabrics, being conductive, possess the capability to attenuate electromagnetic radiation and provide a protective barrier against unwanted radiation.

This review introduces knitted structures, their classification, basic elements of knitted structures, properties of knitted fabrics, electromagnetic shielding effectiveness, the importance of electromagnetic shielding, the mechanism of electromagnetic shielding, and factors affecting electromagnetic shielding performance. The review was conducted with a focus on the effects of electromagnetic shielding on human health, considering knitted fabrics as potential shielding materials. The study thoroughly examined knitted structures, yarn types, and materials used in these fabrics. In addition, the knitting machines employed for fabric production and the fabrication parameters were also analyzed.

Knitted fabrics and their classification

Knitting can be primarily categorized into two types: weft knitting and warp knitting. In weft knitting the fabric formation is row wise and at a right angle to yarn feeding. The resulting structures are known as weft-knitted fabrics or jersey fabrics, and the machines used for their production are called weft knitting machines. In warp knitting, the fabric formation (lengthwise) is in the same direction as the yarn feeding. Our focus will be on weft knitting since our work is associated with this technique.⁷ One way to classify weft knitting is with respect to shape and number of needle bed. A needle bed is a frame on which needles are arranged at a regular pattern. If a machine has a two needle bed, then it is called a double bed knitting machine. If it has a single bed, it is known as a single jersey machine. A flat knitting machine with a single bed, is known as single bed flat knitting machine, and with a double bed, is known as double bed or an inverted V bed flat knitting machine.⁸ For new modifications to the knitted structure, some additional components are attached to the machine. Typically, knitting machines are named according to the attached component, such as a knitting machine. With a pattern wheel is known as a pattern wheel knitting machine, with an intarsia setup attached to the machine, it is known as an intarsia knitting machine, and a machine attached with multi cam tracks is known as a multi cam knitting machine. Knitting machines are also named according to the end products, such as socks knitting machine, terry knitting machine, and sliver knitting machine.⁹

The plain knitting structure is produced on a single jersey machine, while rib, interlock, and purl are manufactured on double needle bed circular knitting machines. There are three basic types of stitches in knit structures: knit, tuck, and miss. Each stitch significantly influences the final properties of the knitted fabric. Introducing miss stitches in a single jersey fabric reduces its width, and incorporating tuck stitches shortens the fabric length. Another essential factor influencing fabric properties is stitch density. A higher stitch density increases the fabric’s areal density (GSM), and conversely, a lower stitch density has the opposite effect.

Application of knitted fabric in technical textile

Knitted fabrics are used as technical fabric in many industrial applications. The major application of conductive knitted fabrics is in the military and aerospace sector. These fabrics offer protection against electromagnetic radiation and can be seamlessly incorporated into wearable textiles for the use of soldiers and astronauts. Technical knitted fabric has another significant application in the automotive industry, particularly in heated seats and sensor integration.¹⁰

Electromagnetic radiation (EMR)

Phones and many household and industrial electronic equipment emit electromagnetic radiation (Figure 1). Security equipment (such as antitheft and airport security gates), communication devices (both terrestrial and aerial), military equipment, and medical devices (such as electrosurgical knives) also emit electromagnetic radiation.¹¹ Human body can absorb these electromagnetic radiation and converts them into thermal energy, resulting in an elevation of body temperature by 1°C–2°C.¹²

Figure 1.

Human life in the sea of electromagnetic waves.^13,14

The electromagnetic spectrum is the range of all type of electromagnetic radiation. It includes the radio wave, microwave, infrared, visible, ultraviolet, x ray and gamma rays. The emission of radiation from electromagnetic spectrum is in the form of photons.

A photon is a unit of electromagnetic energy representing a single wavelength or frequency shown in Figure 2. The units of measurement for photons are electron volts. Human are prone to electromagnetic radiation from natural (sunlight) and artificial sources (radio sets, microwave ovens, etc.). These electromagnetic waves travel through solids, air, and space at constant speed. The shorter the wavelengths, the higher the frequencies, and conversely, the longer the wavelengths, the lower the frequencies. Figure 3 represents different ionizing and non-ionizing radiation.

Figure 2.

Electromagnetic wave.¹⁵

Figure 3.

Types of electromagnetic radiation based on their ionization capability.⁹⁷

Table 1 gives different bands of radio and microwave.¹⁶ Hertz is the unit of frequency measurement (cycles per second). Wavelength is measured in meters.¹⁷

Table 1.

Classification of different radio and microwave with respect to frequency .¹⁶

Waveband	Frequency (GHz)	Sources/applications
L-band	1–2	Radars, mobile & satellite communication, satellite navigation (like GPS, GLONASS etc.)
S-band	2–4	Mobile communications, weather/ship radar systems, Bluetooth, Wi-Fi
C-band	4–8	Full-time satellite TV networks or raw satellite feeds
X-band	8–10	Higher-resolution imaging for target identification, civil, military and government radar applications
Ku-band	12–18	VSAT systems on ships, satellite TV
K-band	18–26	Astronomical observations and radars
Ka-band	26–40	Communications with satellites
Q-band	33–50	Terrestrial microwave communications, radio astronomy studies and automotive radars.
U-band	40–60	Satellite and high-speed terrestrial communications
V-band	50–75	Wireless backhaul and point to point/point to multi-point radio links
W-band	75–110	Automotive radars, satellite communication, astronomy, defense, and security applications
F-band	90–140	Satellite television broadcast, microwave devices and radio astronomy
D-band	110–170	Microwave remote sensing, amateur radio, directed energy weapon, millimeter wave scanner
Millimeter band	110–300	High-bandwidth WLANs and short-range personal area networks

The exposure of human body to electronic devices is unavoidable. The electromagnetic wave may not instantly affect any human, but its long-term exposure may be harmful for the human body. Table 2 represents commonly encountered electromagnetic radiation by humans.

Table 2.

Commonly encountered electromagnetic radiation by humans .¹⁸

Electromagnetic source	Frequency range
Transmission lines	50–60 Hz
Computer monitors	60–90 Hz
AM radio transmissions	530–1600 kHz
FM radio transmissions	88–108 MHz
Television transmissions	50–700 MHz
Headphones	850 MHz–2.4 GHz
Microwave ovens	2.45 GHz
Laptops and Wi-Fi	2.4 GHz
Cell phone tower	0.8–1.9 GHz

A study found that the amount of radiation at 41 MHz near the transmission tower is too harmful for human bones up to 1 m circle, and if it goes to 202 MHz, it is dangerous for human bones within 10 m circle from the tower.¹⁹

Effect of EMR on electronic equipment and human health

High-intensity micro waves have negative consequences on the human body, but low-intensity microwaves may also cause neuropsychiatric problems, referred to as microwave syndrome. Research findings consistently indicate that microwave electromagnetic fields (EMFs) emitted by cell phone base stations, mobile devices, and Wi-Fi smart meters produce neuropsychiatric effects in humans. Common problems due to exposure of electromagnetic radiation (EMR) are summarized in Table 3.

Table 3.

Problems due to exposure to radio and microwave radiation.

No. Sr.	Sources of radio and microwave radiation	Associated problems	Reference
1	Living near and under the mobile phone poll	Headaches, memory abnormalities and reminiscing, dizziness, tremors, and depression	Abdel-Rassoul et al.²⁰
2	Use of cell phones and screens by university students	Headache, fatigue, nervousness, and difficulties in concentrations	Mortazavi et al.²³
3	Microwaves due to cell phone tower and usage of mobile phone	Sleep disruption, headaches, weariness, sadness, dysesthesia, and focus dysfunction, promotion of carcinogenesis and the induction of genetic damage	Pall²⁸, WHO³⁰
4	Exposure to 890 MHz frequency of GSM	An increase in the serum transthyretin (TTR) in 60 min	Söderqvist et al.³¹
5	Exposure to 900 -MHz pseudo-GSM test signal	Sleep problem	Fritzer et al.³²
6	Residing near the mobile phone tower	Depression, headache, cerebral symptoms, dizziness, disorders of optical and acoustic sensory systems, sleep disturbance, skin changes	Eger and Jahn²¹
7	Microwave exposure (0.6–9.5 GHz)	Neurological (peripheral nerves and ganglia), dermographism (skin responses), irritability, depression, loss of appetite, concentration difficulties, peripheral ganglia, and nerve dysfunction	Johnson Liakouris²⁶
8	Microwave exposure on humans up to 1062 kHz	Interpersonal sensitivity, depression, anxiety, hostility, phobic anxiety, paranoid ideation, psychoticism, and sleeping disturbance.	Akdag and Dasdag²⁷
9	Cell phone use during charging	Headaches, concentration problems, weariness, and sleep disruptions as general symptoms, and ear warmth and flushing	Durusoy et al.²²
10	Making calls and text in lavatory	Difficulty in sleep and depression	Thomée et al.²⁵
11	Usage of mobile phone for call	Increase in tympanic temperature	Bortkiewicz et al.²⁴

Eger and Jahn investigated people who lived near a mobile phone signal tower. A questionnaire was distributed to all households asking them about any symptoms or changes they had experienced. The findings were surprising; many people complained of headaches (23.5%), memory abnormalities (28.2%), and reminiscing dizziness, tremors, and depression (48.3%).^20–23 Thomée et al. studied the effects of mobile phone use in adults. People who make calls late at night have trouble sleeping and take longer to fall asleep and their body temperature rise (particularly the ear temperature).^24,25 In 1998, Johnson Liakouris reported that exposure to microwaves caused neurological problems, skin problems, anxiety, and nerve dysfunction in people working in the US embassy.²⁶ Akdag and Dasdag investigated 25 individuals employed by a UHF television station. They experienced various changes including sadness, anxiety, aggression, phobic anxiety, paranoid ideation, psychoticism, and sleep disruption (Figure 4).²⁷

Figure 4.

Non-cancerous effects of low frequency radiation on human body.

Pall studied neuropathy symptoms that occur due to microwaves. The prevalent complaints were sleep disruption, headaches, weariness, sadness, dysesthesia, and focal dysfunction.²⁸ According to a World Health Organization (WHO) report, mobile phone radiation is harmful for the human body. It can increase the risk of carcinogenesis and genetic damage.^29,30 Söderqvist et al. investigated people who were exposed to mobile phone signals. After 60-min exposure, they discovered a considerable increase in serum transthyretin (TTR). TTR is a primarily produced protein in the human liver.³¹ Researchers conducted a study where they analyzed the brain activity of sleeping individuals using Electroencephalography (EEG) while exposing them to nonthermal microwave beams. EEG helps assess brain activity, and any changes can be identified. They observed that these EEG patterns were similar in people exposed to Wi-Fi radiation.^32–35

Electromagnetic radiation (EMR) can cause brain tumor, testicular infertility, or cancer, which is caused by an increase in reactive oxygen species (ROS). Mobile phones and testicular cancer have a bio interaction mechanism. It damages biological systems and alters multiple processes, including a drop in male sperm count, changes in enzyme and hormone imbalance, and DNA damage. Therefore, men should not place their cell phones in their front trouser pockets.^36–38 Heat flux densities of laptop and mobile phones with and without Wi-Fi are given in Table 4.

Table 4.

Depict heat flux density from laptops and mobile phones.

	Wi-Fi connection		Mobile phone		Laptops		Reference
	For mobile phone	For laptop	Without Wi-Fi mobile phone	With Wi-Fi mobile phone	Without Wi-Fi laptop	With Wi-Fi laptop	Reference
Heat flux density (µW/cm²)^a	0.001	2.2–0.013	0.01–0.1	1–40	0.3	(2.2–8.7)	Avendaño et al.³⁹, Okechukwu⁴⁰, Foster and Moulder⁴¹, Peyman et al.⁴²

Heat flux density measurement unit is the microwatt per square meter (µW/m²; which is 1 mW of heat energy transmitted across a one-square-meter area i.e. normal to the direction of the heat flux).

Cell phone exposure for more than 10 years increases risk of brain tumor. Short-term exposure to microwave radiation causes tissue heating. These heated tissues possibly caused red blood count changes, somatic mutations, increased spontaneous abortion, and increased brain and breast cancer. Youngsters usually face sleep disturbance and depression. The researcher concluded that the increase in mobile phone usage led to the development of brain tumors in young adults. Residents living close to mobile phone base stations are constantly exposed to radiation. They are more prone to radiation, and the problem of headache is common.^43–48

Infertility due to usage of laptop and mobile phones

Infertility in young couples is becoming an increasingly global issue. Male fertility has decreased significantly over the last decade. Infertility causes are several environmental factors including electromagnetic waves (EMW). The male testis has germinal epithelium (which includes spermatogonia) that is more radiosensitive than the other cells.^49–51 Male infertility occurs when a guy has a low possibility of making his female partner pregnant. Some of the causes that lead to lower levels of sperm count are long sitting, electromagnetic radiation long term exposure, living in hot environment, and high stress levels. Electromagnetic radiation (EMR) is one of major factors affecting male fertility (Figure 5).^52,53

Figure 5.

Factors effecting human sperm count.⁶²

When a laptop is connected to a Wi-Fi router and directed to a charging port, radiation are emitted. Radiation can affect a wide range of organs. The heat generated by the laptop computer also affects the male scrotum. When individuals use laptops on their laps, the produced heat and radiation fall directly into the genital area (Figure 6).

Figure 6.

Effect of electromagnetic wave (EMW) on testes.³⁶

The impact of radiofrequency radiation (RFR) from a 2.4 GHz laptop antenna on human sperm was evaluated in an in vitro pilot study. Ten sperm samples were obtained from donors aged between 20 and 30 years. Sperm motility was significantly different between exposed and unexposed samples. Many sperm sections are affected by radiofrequency radiation (RFR).^54,55 Human spermatogenesis (responsible for the development of sperm cells) is temperature dependent, and its temperature is 1°C–2°C below the core body temperature. If the temperature increases compared to scrotal hyperthermia, it disrupts intratesticular oxidative equilibrium, which results in oxidative stress, cell death, and damage to sperm DNA integrity.⁵⁶

There are more than 700 million cellphone subscribers in the world.⁵⁷ Analog phones were used between 450 and 900 MHz. Third-generation phones operate at approximately 2000 MHz, whereas digital phones (also known as GSM) operate between 850 and 1900 MHz. The power density of a mobile phone’s first 5 min is frequently higher than that of the phone’s remaining calls.⁵⁸ According to a survey conducted in different hospitals in Pakistan, 97% of doctors reported that extensive usage of mobile devices has a negative impact on human health, and only 3% reported no health effects.⁵⁹ Semen analysis of mobile phone users showed that cell phone radiation produces oxidative stress, which reduces sperm motility and viability (Figure 7). It is vital to note that many guys keep their cell phones in trouser pockets while using Bluetooth. This method exposes the testes to higher levels of cell phone radiation than a phone in the standby mode.^60,61

Figure 7.

Use of mobile creating oxidative stress.^18,59,62

To avoid these problems, humans should save themselves from this toxic radiation. To provide electromagnetic shielding, shielded fabrics must be used.

Importance of (EMI) shielding

Electromagnetic shielding is vital to prevent unwanted radiation interference. In electronic devices and systems, electromagnetic interference (EMI) can disrupt the functioning of components, leading to malfunctions. Signal integrity is critical in communication systems, and electromagnetic shielding helps to maintain it by reducing the impact of external electromagnetic noise. By confining the electromagnetic fields within the shielded region, crosstalk is minimized. Shielding also ensures a safe environment by protecting individuals from excessive exposure to electromagnetic radiation. In addition, it is crucial to safeguard sensitive information from interception or tampering with external electromagnetic sources. In scientific and medical settings, electromagnetic shielding is used to maintain the accuracy and reliability of the measurements and experiments. In aerospace and defense systems, it is essential to properly function the electronic equipment in challenging electromagnetic environments. It also protects women from the harmful effects of EMI radiation, as previously discussed.

Mechanism of electromagnetic interference (EMI) shielding

Electromagnetic shielding is a process of barricading electromagnetic radiation. When a wave interacts with a material, it undergoes two primary mechanisms: reflection or absorption. In reflection, the wave is redirected back to the external environment. Upon absorption, two potential outcomes emerge: transmission through the material or the occurrence of multiple reflection leading to wave attenuation.⁶³

The probability of wave reflection upon striking a material is influenced by the impedance and reflective index of the material. A substantial impedance mismatch increases the probability of reflection. When the reflective index of the material is significantly different from that of the surrounding medium (another material), reflection is more likely to occur. At the atomic level, when an electromagnetic wave interacts with a material, it causes electrons to move, creating secondary waves that interfere with the incident wave, ultimately resulting in reflection. The second mechanism is absorption, when a wave is absorbed by a material, it means the energy from the wave gets taken in by the electrons in the material. This can make the electrons move to higher energy levels, leading to effects like an increase in the material’s temperature. The scattering effect and inhomogeneity in a material caused the multiple reflections mechanism.^64,65

Parameters of electromagnetic interference shielding effectiveness

The incident electromagnetic wave (E_I) may experience reflection E_R (bouncing back from the material; Figure 8). Alternatively, it may penetrate the material. If penetration occurs, the wave undergoes absorption E_A and subsequent transmission E_T, elucidated by equation (1). The total electromagnetic shielding effectiveness (SE_T) is calculated as the sum of absorption (SE_A), reflection (SE_R), and multiple internal reflection (SE_MR) as shown in equation (2).

E_{1} = \sum E_{R} + \sum E_{A} + \sum E_{T}

(1)

Figure 8.

Mechanism of electromagnetic interference shielding.

The waves produced at each phase of the reflection and transmission mechanisms can induce constructive and destructive interferences.⁶⁶ The shielding effectiveness due to absorption is calculated with the help of equation (3). The shielding effectiveness due to reflection is calculated from equation 4.⁶⁷

{SE = SE}_{R} {+ SE}_{A} {+SE}_{MR}

(2)

{SE}_{A} = 10 \log_{10} (\frac{1 - | S 11 |^{2}}{| S 21 |^{2}})

(3)

{SE}_{R} = 10 \log_{10} (\frac{1}{1 - | S 11 |^{2}})

(4)

Here, S₁₁ shows the power loss on port 1 due to the presence of surface reflection coefficient on port 1. S₂₁ is the power loss on port 2 due to surface transmission loss on port 1. When SE_A > 10 dB, then SE_M neglected, and the SE_total is define as equation (5).

{SE}_{total} {=SE}_{R} {+ SE}_{A}

(5)

In an ideal condition where the material exhibits perfect symmetry, and the sample size and edges are smooth, the S-parameters consisting of reflection, absorption, and transmission, can be precisely defined through equations (6)–(8).

R = | S 11 |^{2} = | S 22 |^{2}

(6)

T = | S 12 |^{2} = | S 22 |^{2}

(7)

A = 1 - R - T

(8)

*Here, R = Reflection coefficient, T = transmission coefficient, A = total absorption of EM waves by material.

Reflection loss

The reflection loss is defined as the decrease in the intensity or amplitude of a wave when it encounters a boundary between two different media. The magnitude of reflection loss is influenced by factors such as impedance matching, frequency measurement, material thickness, and shielding material concentration. The smaller the impedance difference between two mediums, the lower the reflection loss will be. At higher frequencies, the reflection loss will decrease. Additionally, thicker materials will result in greater reflection loss. Moreover, the greater the amount of shielding material, the higher the reflection loss will be.

RL is the reflection loss of the material measured in decibel (dB) as give in equation (9).

RL = 20 \log | S11 |

(9)

Here: $S 11 = \sqrt{{Real part of (S 11)}^{2} {+ Imagnary part of (S 11)}^{2}}$

Multiple reflection

Multiple reflections result from the reflection at various surfaces of shielding material due to its large surface area, and porous structure. Its mechanism is defined as the second boundary’s reflected wave as redirected to the first boundary by thin shielding material, where it is reflected multiple times before returning to the second boundary. These multiple reflections can be ignored in two cases, when the material’s thickness is larger than skin depth or when the value of SE_A > 10 dB. The multiple reflection (SE_M) is given in equation (10).

{SE}_{M} {= 20log(1-e}^{-2t/} δ)

(10)

Here “t” is the thickness of the shielding material in mm, $δ^{'} i s t h e s k i n d e p t h i n m m .$

Absorption loss mechanism

Absorption loss refers to the reduction in electromagnetic energy that occurs as the shielding material absorbs and dissipates incident electromagnetic waves. The amplitude of an electromagnetic wave exponentially decreases as it passes through a shielded medium. This is because the current created in the medium causes ohmic loss and material heating owing to absorption loss. The absorbance could be measured in percentage (%), and the maximum value of absorbance for any material is calculated from equation (11).

S E_{A} = 20 L o g_{10} [e^{\frac{t}{δ}}]

(11)

Here “t” is the thickness of the shielding material in mm, $δ^{'} i s t h e s k i n d e p t h i n m m$ .

Skin depth

The virtual distance that a wave travels in the structure of a conductor material before decaying by a factor of (1/e 0.37%) from its value on the surface (equation (12)).

δ = 1 / \sqrt{π} f μ σ

(12)

Where frequency (f), magnetic permeability ( $μ$ ) = $μ_{o} μ_{r}, μ_{r} i s r e l a t i v e m a g n e t i c p e r m e a b i l i t y$ , $μ_{o} = 4 \times 10^{- 7}$ Hm⁻¹, ( $σ$ ) is the electrical conductivity in Ω⁻¹m⁻¹⁶⁶. Hence, with an increase in conductivity or permeability of the material and frequency of incident waves, the skin depth of the shield decreases. This parameter helps determine the absorption and reflection of electromagnetic radiation. At higher frequencies, the skin depth effect is less pronounced, indicating that electromagnetic shielding is concentrated more on the material’s surface.

Electrical conductivity and loss tangent

Electrically conductive materials serve as low-impedance pathways for the flow of electrical current. Utilizing conductive materials leverages the skin effect, ensuring that a substantial portion of electromagnetic energy remains confined to the material’s surface. This facilitates more efficient reflection or absorption of the electromagnetic wave. Due to inherent electrical conductivity, conductive materials can absorb electromagnetic energy. The fabric sample electrical conductivity is calculated using equation (13).

σ = 2 \prod \int ε_{0} ε^{″}

(13)

Where $f$ is the measured frequency in Hz, $ε_{o}$ is the permittivity of free space ( $ε_{o}$ =8.854 × 10⁻¹² F/m) and $ε^{″}$ is the imaginary part of permittivity. The conductivity is measured in Simon per centimeter (S/cm).

Loss tangent

The loss tangent is calculated according to equation (14)

Loss tangent (\tan δ) = (\frac{ε^{″}}{ε^{'}})

(14)

Here the $ε^{″}$ is the imaginary part of permittivity and $ε^{'}$ is the real part of permittivity. Loss tangent is a ratio, so it has no units.^68,69

Measurement techniques of EMI shielding

The four most commonly used techniques for the measurement of electromagnetic shielding.

Open field method

Shielded box method

Shielded room method

Co-axial transmission probe method

Figure 9 shows the open-field box method. The sample is positioned between the transmitting and receiving antennas. The transmitting antenna emits a known electromagnetic signal, usually at a specific frequency. The receiving antenna is positioned 30 m away on the other side of the sample to measure the transmitted signal. The open-field method provides a relatively simple and practical method to evaluate the shielding effectiveness of materials under real-world conditions.

Figure 9.

Line diagram of open field shielding for the measurement of electromagnetic interference shielding.⁷⁰

Figure 10 shows the shielded box method. In this approach, the sample is positioned on the wall of the shielded box alongside a receiving antenna, while the transmitting antenna is located outside the box. The intensity of the transmitted radiation is measured after passing through the material. But the disadvantage of this method is limited to the frequency range of 500 MHz.

Figure 10.

Line diagram of shielded box method for the measurement of electromagnetic interference shielding .⁷¹

Figure 11 shows shielded room method, it is a technique used for evaluating the electromagnetic shielding effectiveness of materials within an enclosed space. This method typically involves the use of a shielded room or chamber to create a controlled environment for testing. In which the signal generator, transmitting antenna, receiving antenna and recorder are isolated in a separate room.

Figure 11.

Line diagram of Shielded room method line diagram for the measurement of electromagnetic interference shielding .⁷²

The co-axial transmission probe method uses transmission and receiving coaxial cables, a metallic material holder, and a vector network analyzer for data analysis. Figure 12 shows that the vector network analyzer records the intensity of the electromagnetic radiation transmitted and received across a broad frequency range. Unlike antennas, coaxial probes generate electromagnetic radiation with low losses over a broad frequency spectrum. The outcomes are derived in the form of the scattering parameters, which include transmitted, reflected, and absorbed waves, which are calculated using specific formula.⁷³

Figure 12.

Co-axial transmission probe method [EpsiMu].

Literature review

Electromagnetic radiation is everywhere and can cause illnesses in humans (skin allergy, cancer, tumors, etc.).⁷⁴ Metals, conductive polymers, and conductive coated materials are among those materials that can protect humans from electromagnetic radiation (EMR).⁷⁵ However, their usage in textile apparel effectively protects the human body from electromagnetic radiation, which can have harmful effects on human health.

Wearable shielding materials should be flexible, lightweight, comfortable, easy to carry, and inexpensive. There are many shielding materials available, including polymer films, composites, metal-based materials, and textiles. Textile-based shielding products are flexible, and breathable etc. Textile fabrics are further categorized into woven, nonwoven, and knitted fabrics. Knitted fabrics are the most suitable textile technology because they are less expensive, easy to form, and lightweight.⁷⁶ However, knitted fabrics incorporating conductive materials are difficult to manufacture, as knitting needles are more sensitive to wear and tear compared to weaving machine parts. Nonetheless, with proper expertise and careful adjustment of processing parameters, conductive materials can be successfully used in knitting.

EMI shielding materials used for fabric manufacturing

Gupta et al. worked on a core sheath base conductive yarn. They found that 100% stainless steel yarn had higher electromagnetic shielding than yarn with 50% stainless steel.⁷⁷ However, the 100% usage of the metal wire is not possible on knitting machine because it creates a lot of needle damage. A selective ratio can be applied where more than 50% wire content is suitable for the intended purpose. Bedeloglu prepared two yarns, one with a stainless-steel wire and the other containing acrylic, and concluded that a wire-based yarn provides electromagnetic shielding (40 dB at 0.31 GHz) compared to a simple acrylic yarn. Fabrics incorporating stainless steel wires can be utilized for protective, safety, and military applications, offering both flexibility and comfort.⁷⁸ However, the blending of natural yarn with conductive yarn at an appropriate ratio needs to be studied. The blended yarn should be structured in a way that ensures a firm grip of the conductive fibers within the yarn, as loose fibers may potentially damage the electronic circuits of the machine. Lin et al. created a yarn with stainless steel, polyester, and bamboo charcoal, wrapped at 6.5 turns/cm. They concluded that more lamination layers improved the electromagnetic shielding effectiveness (EMSE). Using 0.04 mm diameter stainless steel wires enhances air permeability but reduces rigidity compared to 0.08 mm diameter wires.⁷⁹ However, the smaller diameter wire create ease during the manufacturing of fabric samples. Cheng et al. concluded that the knitted fabric delivers electromagnetic shielding (EMSE) more successfully, especially when conductive filler with a greater stainless-steel content was used.⁸⁰ However, the performance of stainless-steel wire decreases at higher frequencies. Stainless steel wires also provide the best result in aspect to shielding.^78,81–87 Kayacan concluded that structures with a greater amount of stainless steel have higher electromagnetic shielding (EMSE) values.⁸⁸ However, literature shows that it is only applicable to electromagnetic radiation in the low-frequency range.⁸⁹

Knitted fabrics were created using stainless steel and copper wires on a flatbed hand knitting machine. The fabrics with double-ply wires exhibited better electromagnetic shielding.⁹⁰ However, their areal density will increase, and a higher wire content will also raise the cost of the final product.⁹¹ Copper is also considered a suitable material for shielding.^92,93 Copper/cotton core-spun yarn was manufactured, and copper wires of various diameters (0.06, 0.07, and 0.08 mm) were used as core components. Full milano and 1 × 1rib knitted fabrics were prepared on a machine gauge (8, 10, and 12 per inch). The results indicated that the electromagnetic shielding of the heavier and thicker fabric was significantly greater than that of the lighter fabric.⁹⁴ However, at lower frequencies, the attenuation capacity of copper is lower compared to stainless steel.⁹⁵ Cotton-covered copper wire with diameters of 0.1, 0.11, and 0.12 mm was utilized to develop yarn. Among the plain, rib, and interlock structures, the interlock structure exhibited the highest electromagnetic shielding. Furthermore, an increase in the diameter of the copper wire leads to a decrease in the electromagnetic shielding value.⁹⁶ However, this is not the case for all conductive materials; increasing copper thickness reduces attenuation capacity because copper has poor magnetic shielding properties.

Pamuk et al. studied the electromagnetic shielding capabilities of fabrics made entirely of carbon. These carbon-based fabrics demonstrated the best shielding performance at various frequencies.⁹⁷ However, carbon has the highest tendency to absorb incoming radiation, but it cannot be used directly on human skin due to its potential to cause skin allergies and its high cost.⁹⁸ Generally, carbon fiber is used for better microwave absorbing properties.^99,100 A composite yarn composed of carbon and stainless steel was prepared. Electromagnetic shielding was tested in single and multiple layers, revealing that both carbon and stainless steel contributed to reducing electromagnetic interference. The shielding effect was also increased with the number of layers of knitted fabrics.¹⁰¹ However, electromagnetic interference generally decreases with an increase in the number of layers. If carbon is present, its ability to absorb radiation improves, so increasing the thickness further enhances radiation absorption.

A fabric knitted from polyamide and silver-coated thread works well in blocking electromagnetic waves between 0.8 and 2.4 GHz. Even after being washed and cleaned 20 times, the fabric’s ability to shield against electromagnetic waves stays the same.¹⁰² Silver coating is widely used today in applications that require electromagnetic shielding. Silver coating provides better electromagnetic shielding compared to copper and stainless steel.¹⁴ However, coating conductive material is an easy method to attenuate electromagnetic radiation, but its effectiveness is limited to a few washes. The main drawback is the reduction in performance over time.

Lin et al. manufactured a knitted fabric from stainless steel (SS)/polyester (PET)/bamboo charcoal (BC) wrapped yarns. The yarns were designated as 0.04W and 0.08W, respectively (0.04 and 0.08 denoting the diameter of stainless steel (SS) wire and W denoting wrapped yarns). The five-layered knits exhibited an optimal electromagnetic shielding (EMSE) of −30 to −50 dB at a frequency of 2250 MHz.⁷⁹ The number of layers increased the electromagnetic shielding (EMSE) value.¹⁰³ In multilayer fabrics, the layering sequence also impacted the electromagnetic shielding (EMSE) effectiveness.¹⁰⁴ Yu et al. recommended a two-layer conductive fabric to protect an individual from electromagnetic (EM) radiation.¹⁰⁵ The different layering angles changed the shielding effectiveness.¹⁰⁶ Taylor et al. investigated the multilayer textile, and concluded that multilayer textiles with 90° intervals produced a higher level of electromagnetic (EM) shielding than those with 0° and 45° stacking angles.¹⁰⁷ The researchers concluded that a double-layer fabric with 90° layering produces good results.¹⁰⁸ However, multilayer fabrics offer excellent electromagnetic shielding properties when they incorporate different structures and materials. Castano and Flatau concluded that the conductivity of knitted fabric was found to change significantly when the percentage of the conductive yarn was increased.^109,110 The thickness and quantity of conductive wires both help to increase the electromagnetic shielding (EMSE) effectiveness.¹¹¹ Ceken and Ozkurt used the two-ply copper wire in its knitted structures. Two-ply copper wire fabric shielded effectively in the low and medium frequency bands.^90,112 At higher frequencies, smaller diameter wires and knitted structures add significant results.¹¹³ However, copper wire is not suitable for shielding against low-frequency electromagnetic radiation, and the cost end product is also high in such cases.

Effect of knitted structures on electromagnetic shielding effectiveness

A summary of weft knitted fabrics for electromagnetic interference shielding application is given in Table 5. Knitted fabrics also have the capability to shield electromagnetic waves effectively.¹¹⁴ A single cone can be used to fabricate knitted fabrics and raveling property from the last end also made it famous when used as a medical sensor as compared to woven.^115,116 However, knitted fabrics were previously avoided for electromagnetic interference shielding applications due to their porous structure. With advancements, it is now possible to control the hole size and attenuate electromagnetic radiation.

Table 5.

Weft knitted structures for electromagnetic shielding.

Knitted structure	Textile material	Shielding material	Maximum shielding achieved	Variable investigated	Reference
Single jersey	Bamboo	Stainless steel, charcoal	30 dB at 2012–2318 MHz (Absorption)	Single structure with different angle stacking sequence	Hwang et al.¹¹⁰
Double pique / Lacoste knit structure	Cotton	Cu/PAC	34 dB at 1160 MHz/ 40 dB at 1175 MHz	Different structures with different yarns	Taylor et al.¹²²
Double jersey (Milano rib)	Cotton	Copper and silver wire	20 dB at 1.7–2.6 GHz	Different knitted structures	Abdulla et al.¹²⁰
Interlock double jersey	Elastomeric yarn	Cobalt and stainless-steel metal yarns (hybrid).	Average 19 dB, between frequency 1160 and 1660 MHz	Knitted structure washing	Kayacan⁸⁸
Pique knitted structure	Cotton	Siro spun with metal core	5 dB. at 0.25 GHz	Presence of tuck stitches	Ortlek et al.⁸¹
Interlock knitted structure	Cotton	Stainless steel, copper, gold	>60 dB. for professional use	Different shielding material	Sancak et al.¹¹¹
Double face pique	Cotton, polyester	10% metal fiber (stainless steel)	30 dB. 4 Hz frequency	Constant percentage of metal yarn	Safarova and Militky¹²⁵
Single jerseys knitted	Cotton	Stainless steel, Cooper	22 dB at 1–5 GHz	One structure with multiple yarns	Tezel et al.⁷³
Interlock and single jersey	Cotton polyester	Cotton and polyester	0.9 dB at 1.5 GHz	Different knitted structure	Palanisamy et al.¹³⁴
Single jersey fabric	-	Stainless steel and copper wires embedded in the structure	30 dB at 1550 MHz	Different plain knitted structures	Ceken and Ozkurt⁹⁰
Half milano rib knitted	Cotton	Stainless steel	45 dB at 0.25 GHz	Different knitted structures	Tunakova et al.¹⁰⁸
Interlock	Cotton	Copper in core of yarn	46–63 dB at 750–1000 MHz	Plain, rib and interlock structure, tightness factor	Perumalraj and Dasaradan⁹⁶
Rib and its derivatives 1 × 1,2 × 1,2 × 1	Basalt	Stainless steel/polyester produced	20–22 dB at 750–3000 MHz	Plain and rib derivatives	Cheng et al.⁸⁰
Plain plaited	Acrylic	Stainless steel	25 dB at 2640 MHz	Different knitted structure	Ceken et al.¹²⁶
In lay 1 × 1 Rib knitted	Cotton	Copper wire use	18–21 dB at 180–300 MHz	Different structures performances at a different frequency	Taylor et al.¹¹⁷
Double knitted tube	Cotton	Steel and copper hybrid yarn	1710–1785 MHz	Plain knit and double-knit structure	Ciesielska-wróbel and Grabowska¹¹⁴
Full milano knit	Cotton	Copper	39 dB. at 0.63 GHz	Rib and milano and plain knitted structure	Hamed et al.⁹⁴
Plain knitted	Cotton	Copper wire	20–40 dB at 27–300 MHz	Different courses and wale density and wire diameter	Soyaslan¹¹²
Plaited knitted	Bamboo, polyester	Bamboo charcoal, polyester, stainless steel wire	-5 dB at 3000 kHz to 3 GHz	Plain and plaited socks on the jacquard sock machine	Yu et al.¹²⁸
Plain knit and 1 × 1 rib knit	Cotton	Nano silver coating plaited yarn	30 dBm at 500–1000 MHz	Plain and rib with different 5- and 7-gauge machine	Kumar et al.¹³³
Single jersey and plaited jersey	Cotton	Silver-coated copper wire	40 dB at 30–250 MHz	Single jersey and derivatives with antimicrobial properties	Rajendrakumar and Thilagavathi¹²⁷

The effectiveness of electromagnetic interference shielding depends on multiple factors, and the structure of the knitted fabric is a key contributor.¹¹⁷ Double jersey structures have a better electromagnetic shielding (EMSE) value than single jersey fabrics.^96,118 However, this is due to the increased ratio of conductive material at per unit area, not the thickness of the material. Kayacan showed that interlock fabric offer higher electromagnetic shielding (EMSE) after washing than plain knitted fabrics, especially in the lower frequency ranges.^88,119 However, the interlock structure has loops positioned directly opposite to each other, so when radiation falls onto the interlock fabric, it is weakened due to multiple internal reflections. Abdulla et al. investigated different double jersey knitted structures. They found that the rib-derived Milano fabric has better electromagnetic shielding (EMSE). This is due to the yarn’s ability to form a loop on the front surface of the fabric and a yarn that splits this loop down the middle on its back side. As a result, the pores on the surface became narrower, and the cloth thickened in certain back portions. This aids in the absorption and reflection of the incident wavese.¹²⁰ However, the produced structure cannot provide electromagnetic interference shielding from both sides of the fabric

The presence of knitted stitches especially miss stitches help to provide better results in shielding. This is because the miss knitted stitches reduce the width of the fabric.^90,94,121 The fabrics with tuck stitches also have a tendency to trap upcoming waves. Taylor et al. showed that the better performance of the lacoste can be attributed to the crosswise orientation of the tuck stitches.¹²² However, a large hole (mesh) cannot perform better in electromagnetic interference shielding. In mesh-based fabrics, the hole boundaries should be conductive.¹²³ The size of the mesh holes and number of holes in a mesh had an impact on the shielding efficiency (SE).¹²⁴ A porous knitted structure with a low bulk is considered ideal for the end-use application of electromagnetic shielding.¹²⁵ However, porous knitted fabric with low bulk has been achieved by applying a conductive coating.

The construction techniques during knitted fabric formation also influence the shielding effectiveness. Ceken et al. concluded obtaining promising results is possible with a single jersey fabric when observed from the reverse side. This is because the arc on the back side of the single jersey covers the loop holes, reducing their size and making them narrower from the back.¹²⁶ However, narrowing the holes is not an effective method to attenuate radiation. If the holes are conductive from the inside, they will perform better than simply having narrow holes.

Rajendrakumar and Thilagavathi reported that in knitted fabrics the “plating” technique provided better electromagnetic shielding results as compare to other single jersey derivatives.¹²⁷ However, when the plated knitted fabrics were converted into multilayers, their electromagnetic interference shielding performance was similar to other double jersey multilayer fabrics.¹²⁸ The knitting parameters are an essential factor for better shielding results.¹²⁹ The fabric made with a smaller loop length had a higher electromagnetic interference shielding results. The course wise and wale wise the conductivities of the knitted fabrics were different, and the wales wise conductivity was significantly greater than the transverse (course wise) electrical conductivity.¹³⁰ However, this is due to the greater number of yarn overlaps in the wale-wise direction compared to the course-wise direction in the knitted structure.

Mohamed et al. created a breathing sensor using different ratios of conductive yarn and various knitting parameters. They found that a single jersey fabric, which had less conductive yarns and a higher number of wales (NW), performed the best as a breathing sensor.¹³¹ The metal base coated knitted fabric also produced good electromagnetic shielding results, which can be used for low-cost applications in replacement of metal wires.¹³² Kumar et al. used nano silver coating on knitted fabrics. All knitted samples showed outstanding EMSE values at 500 and 800 MHz (EMSE above 90%) and excellent value at 1000 MHz (EMSE above 70%).¹³³ However, these coatings oxidize easily; therefore, they are not preferred for long-term applications.¹²⁵

Conclusion

Electromagnetic radiation is constantly present in the environment, and its intensity has increased with the widespread installation of Wi-Fi-connected devices. Every person is exposed to electromagnetic radiation, which has harmful effects on the body. There are many products in the market that protect people and devices from these waves but carrying these products all the time is impractical. There are several coated materials that offer protection from electromagnetic radiation; however, they degrade over time due to oxidation and peeling after use or washing. Prolonged exposure to such radiation has been associated with adverse effects on both human health and the environment. Children are particularly vulnerable, as their developing organs are more sensitive to radiation. Reported health issues include depression, anxiety, headaches, loss of concentration, and an increased risk of cancer.

Various methods are available to protect against electromagnetic radiation; however, some are costly, while others block signals to the extent that they render electronic devices unusable. The majority of these radiation falls within the low-frequency range, commonly used for communication. Therefore, one of the most practical and effective solutions is to shield the human body using clothing designed to attenuate electromagnetic radiation.

The two most common methods used for fabric production are weaving and knitting. Knitted fabrics offer advantages such as extensibility, breathability, cost-effectiveness and used for undergarments. The current knitted structures are insufficient to minimize the effect of electromagnetic radiation. The comfort properties of various material related to EMS is insufficient. There is insufficient published work that deals with EMS characteristics and comfort properties of knitted fabrics. The combination of appropriate conductive substances and knitted structures will significantly improve the EMI shielding effectiveness.

The scope of this review was limited to the literature of conductive knitted fabrics tailored for electromagnetic shielding in the low-frequency range. Specifically, the emphasis is on safeguarding radio and microwaves, given their extensive use in communication. This is particularly relevant as modern devices like laptops and mobile phones heavily rely on these low-frequency electromagnetic radiations.

Critical analysis and future directions

Literature confirms the potential application of conductive knitted fabrics in the field of electromagnetic radiation shielding. Knitted fabrics are particularly suitable for next-to-skin garments due to their structural integrity and comfort. While double jersey structures demonstrate superior shielding performance, they tend to be heavier. In contrast, single jersey structures are lighter and more flexible, making them a more practical choice. However, since single jersey fabrics have distinctly different front and back surfaces, their electromagnetic shielding effectiveness varies between the two sides. Therefore, a specialized structure is required, one that is lightweight and exhibits similar characteristics on both sides to ensure consistent shielding performance.

A significant gap exists in the research and application of conductive knitted fabrics. These fabrics have the potential to reduce the frequency and intensity of radiation emitted by electronic devices. One promising approach involves the use of specialized yarns comprising a conductive core and a sheath made of fibers that are compatible with human skin. Additionally, jacquard knitting structures can be engineered specifically for effective radiation attenuation. The development of cost-effective, wire-based knitted fabrics also presents a viable solution for electromagnetic shielding applications.

Footnotes

ORCID iD

Usman Ahmed

Author contributions

Usman Ahmed: Drafted and wrote the main manuscript. Hafiza Bushra Fayyaz: Identified and elaborated on medical issues related to low-frequency electromagnetic radiation. Naeem Ullah: Selected proper images for the research paper. Tanveer Hussain: Reviewed the complete manuscript and provided guidance for improvement. Shehbaz Ahmad: Compiled and formatted the data into tables. Muhammad Sajjad Khan: Created figures and images in accordance with the requirements of journals.

Funding

The authors received no financial support for the research, authorship, and/or publication of this article.

Declaration of conflicting interests

The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Data Availability Statement

The data is available on special request.*

References

David

(ed.). Knitting technology. 3rd ed. Technomic Publishing Co. Limited, 2013. http://www.nber.org/papers/w16019

Sharma

Knitwear Market Size, Share & Trends Analysis Report By Material Type (Natural, Synthetic, Blended), By Category (Men, Women, Kids), By End-Use (Innerwear, Outerwear, Sportswear), By Distribution Channel (Store Based, Non-Store Based) and By Region (NorthA merica, Europe, APAC, Middle East and Africa, LATAM) Forecasts, 2025-2033. Straitsresearch, 2025; 1.

Pakistan Bureau of Statistics. Annual analytical report on external trade statistics of pakistan fy 2021-22, https://www.pbs.gov.pk/sites/default/files/external_trade/Annual_Analytical_Report_On_External_Trade_Statistics_Of_Pakistan_2021-22.pdf (2023).

Pritha

Maliha

Swati

SS.

Covid-19 and post Covid-19 impact on knit and woven ready-made garment industry of Bangladesh. Int J Text Sci 2023; 2: 27–36.

GOP. Advance release on external trade statistics, https://www.pbs.gov.pk/sites/default/files/external_trade/monthly_external_trade/2022/may-2022/Release_Statement_May_2022.pdf (2022).

ITC. Business T statistics for international. Trademap. ITC, 2024; 2.

(ed.). Advances in knitting technology. 1st ed. Woodhead Publishing Limited, 2011.

David

(ed.). Knitting technology. 3rd ed. Technomic publishing co. limited, 2001. https://www.sciencedirect.com/book/9781855733336/knitting-technology

Ray

(ed.). Fundamental and advances in knitting technology. 3rd ed. Woodhead Publishing Limited, 2012.

10.

Vigneswaran

Kandhavadivu

Development of electromagnetic shielding wearable electronic textiles using core conductive fabrics. Int J Sci Eng Appl 2013; 7560: 65–69.

11.

Hours

Khati

Hamelin

Interference between active implanted medical devices and electromagnetic field emitting devices is rare but real: results of an incidence study in a population of physicians in France. PACE - Pacing Clin Electrophysiol 2014; 37: 290–296.

12.

Gherardini

Ciuti

Tognarelli

, et al. Searching for the perfect wave: the effect of radiofrequency electromagnetic fields on cells. Int J Mol Sci 2014; 15: 5366–5387.

13.

Leskowitz

The energetics of group trance: new research, applications, and implications. Energy Psychol J 2014; 6: 34–43.

14.

Safdar

Ashraf

Javid

, et al. Polymeric textile-based electromagnetic interference shielding materials, their synthesis, mechanism and applications – a review. J Ind Text 2022; 51: 7293S–7358S.

15.

Bhattacharjee

Foundation of electromagnetic waves. Int J Sci Dev Res 2022; 7: 143–148.

16.

Manickavasagan

Jayasuriya

Imaging with electromagnetic spectrum. first edit. Springer, 2014.

17.

Luis

Moncayo

(eds). Electromagnetic theory for microwaves and optoelectronics. 2nd ed. Springer, 1998.

18.

Kesari

Agarwal

Henkel

Radiations and male fertility. Reprod Biol Endocrinol 2018; 16: 118–216.

19.

Kumar

Vats

Pathak

PP.

Harmful effects of 41 and 202 MHz radiations on some body parts and tissues. Indian J Biochem Biophys 2008; 45: 269–274.

20.

Abdel-Rassoul

El-Fateh

Salem

, et al. Neurobehavioral effects among inhabitants around mobile phone base stations. Neurotoxicol 2007; 28: 434–440.

21.

Eger

Jahn

Specific health symptoms and cell phone radiation in selbitz ( Bavaria, Germany )— evidence of a dose-response relationship deutsche zusammenfassung. Electromagn fields 2010; 23: 1–20.

22.

Durusoy

Hassoy

Özkurt

, et al. Mobile phone use, school electromagnetic field levels and related symptoms: a cross-sectional survey among 2150 high school students in Izmir. Environ Health 2017; 16: 1–14.

23.

Mortazavi

Ahmadi

Shariati

Prevalence of subjective poor health symptoms associated with exposure to electromagnetic fields among university students. Bioelectromagnetics 2007; 28: 326–330.

24.

Bortkiewicz

Gadzicka

Szymczak

, et al. Changes in tympanic temperature during the exposure to electromagnetic fields emitted by mobile phone. Int J Occup Med Environ Health 2012; 25: 145–150.

25.

Thomée

Eklöf

Gustafsson

, et al. Prevalence of perceived stress, symptoms of depression and sleep disturbances in relation to information and communication technology (ICT) use among young adults – an explorative prospective study. Comput Human Behav 2007; 23: 1300–1321.

26.

Johnson Liakouris

. Radiofrequency (RF) sickness in the lilienfeld study: an effect of modulated microwaves? Arch Environ Health 2010; 53: 236–238.

27.

Akdag

Dasdag

Evaluation of psychologic parameters in people occupationally exposed to radiofrequencies and microwave. Biotechnol Biotechnol Equip 2014; 8(4): 71–74. https://doi.org/10.1080/13102818.1994.10818812

28.

Pall

ML.

Microwave frequency electromagnetic fields (EMFs) produce widespread neuropsychiatric effects including depression. J Chem Neuroanat 2016; 75: 43–51.

29.

Repacholi

MH.

Low-Level exposure to radiofrequency electromagnetic fields: health effects and research needs. Bioelectromagnetics 1998; 19: 1–19.

30.

WHO. Environmental Health Criteria 137 (electromagnetic fields 300Hz to 300 GHz). WHO. Epub ahead of print 1993: 3.

31.

Söderqvist

Carlberg

Hansson Mild

, et al. Exposure to an 890-MHz mobile phone-like signal and serum levels of S100B and transthyretin in volunteers. Toxicol Lett 2009; 189: 63–66.

32.

Fritzer

Göder

Friege

, et al. Effects of short- and long-term pulsed radiofrequency electromagnetic fields on night sleep and cognitive functions in healthy subjects. Bioelectromagnetics 2007; 28: 316–325. https://doi.org/10.1002/bem.20301

33.

Sale

AJH

. A review of microwaves for food processing. Int J Food Sci Technol 1976; 11: 319–329.

34.

Aldhaeebi

Alzoubi

Almoneef

, et al. Review of microwaves techniques for breast cancer detection. Sensors 2020; 20: 1–38.

35.

Rosen

Stuchly

Vorst

AV.

Applications of microwaves in medicine. IEEE Antennas Propag Mag 2005; 47: 106–107.

36.

Fejes

Závaczki

Szöllősi

, et al. Is there a relationship between cell phone use and semen quality? Arch Androl 2005; 51: 385–393.

37.

Aitken

Bennetts

Sawyer

, et al. Impact of radio frequency electromagnetic radiation on DNA integrity in the male germline. Int J Androl 2005; 28: 171–179.

38.

Erogul

Oztas

Yildirim

, et al. Effects of electromagnetic radiation from a cellular phone on human sperm motility: an in vitro study. Arch Med Res 2006; 37: 840–843.

39.

Avendaño

Mata

Sanchez Sarmiento

, et al. Use of laptop computers connected to internet through Wi-Fi decreases human sperm motility and increases sperm DNA fragmentation. Fertil Steril 2012; 97: 39–45.e2.

40.

Okechukwu

CE.

Does the use of mobile phone affect male fertility. J Hum Reprod Sci 2020; 13: 174–183.

41.

Foster

Moulder

JE.

Review paper wi-fi and health : review of current status of research. Heal Phys Soc 2013; 105: 561–575.

42.

Peyman

Khalid

Calderon

, et al. Assessment of exposure to electromagnetic fields from wireless computer networks (Wi-Fi) in schools; results of laboratory measurements. Health Phys 2011; 100: 594–612.

43.

Khurana

Teo

Kundi

, et al. Cell phones and brain tumors: a review including the long-term epidemiologic data. Surg Neurol 2009; 72: 205–214.

44.

Hardell

Carlberg

Hansson

Epidemiological evidence for an association between use of wireless phones and tumor diseases. Pathophysiology 2009; 16: 113–122.

45.

Goldsmith

Epidemiologic evidence of radiofrequency radiation ( microwave ) effects on health in military broadcastingl and occup. Int J Occup Environ Health 2013; 3525: 47–57. https://doi.org/10.1179/oeh.1995.1.1.47

46.

Hossmann

Hermann

DM.

Effects of electromagnetic radiation of mobile phones on the central nervous system. Bioelectromagnetics 2003; 24: 49–62.

47.

Yakymenko

Sidorik

Risks of carcinogenesis from electromagnetic radiation of mobile telephony devices. Exp Oncol 2010; 32: 54–60.

48.

Kundi

Hutter

Mobile phone base stations — effects on wellbeing and health. Pathophysiology 2009; 16: 123–135.

49.

Fischbein

Zabludovsky

Eltes

, et al. Ultramorphological sperm characteristics in the risk assessment of health effects after radiation exposure among salvage workers in Chernobyl. Environ Health Perspect 1997; 105: 1445–1449.

50.

Intano

McCarrey

, et al. Recovery of a low mutant frequency after ionizing radiation-induced mutagenesis during spermatogenesis. Mutat Res Genet Toxicol Environ Mutagen 2008; 654: 150–157.

51.

Boivin

Bunting

Collins

, et al. Al. International estimates on infertility prevalence and treatment seeking: potential need and demand for medical care. Hum Reprod 2009; 24: 2380–2383.

52.

Kuroda

Usui

Sanjo

, et al. Genetic disorders and male infertility. Reprod Med Biol 2020; 19: 314–322.

53.

Bak

Seok

Song

, et al. Hormonal imbalances and psychological scars left behind in infertile men. J Androl 2012; 33: 181–189.

54.

Oni

Amuda

Gilbert

CE.

Effects of radiofrequency radiation from wifi devices on human ejaculated semen. IJRRAS 2011; 9: 292–294.

55.

Mortazavi

SAR

Taeb

Mortazavi

SMJ

, et al. The fundamental reasons why laptop computers shoud not be used on your lap. J Biomed Phys Eng 2016; 6: 279–284.

56.

Saikhun

Kitiyanant

Vanadurongwan

, et al. Effects of sauna on sperm movement characteristics of normal men measured by computer-assisted sperm analysis. Int J Androl 1998; 21: 358–363.

57.

Agarwal

Deepinder

Sharma

, et al. Effect of cell phone usage on semen analysis in men attending infertility clinic: an observational study. Fertil Steril 2008; 89: 124–128. https://doi.org/10.1016/j.fertnstert.2007.01.166

58.

Usikalu

Akinyemi

ML.

Monitoring of radiofrequency radiation from selected mobile phones. J Appl Sci Res 2007; 3: 1701–1704.

59.

Rsa

, et al. Impact of excessive mobile phone usage on human. J Comput Sci Syst Biol 2016; 09: 173–177. https://doi.org/10.4172/jcsb.1000235

60.

Agarwal

Desai

Makker

, et al. Effects of radiofrequency electromagnetic waves (RF-EMW) from cellular phones on human ejaculated semen: an in vitro pilot study. Fertil Steril 2009; 92: 1318–1325.

61.

Srinivas Belur Veerachari

. Mobile phone electromagnetic waves and its effect on human ejaculated semen : an in vitro study. Int J Infertil Fetal Med 2012; 3: 15–21.

62.

Kumar

Singh

AK.

Impact of environmental factors on human semen quality and male fertility: a narrative review. Environ Sci Eur 2022; 34: 1–13. https://doi.org/10.1186/s12302-021-00585-w

63.

Zhang

Liu

Lightweight electromagnetic interference shielding materials and their mechanisms. In: Han

M-G

(ed.) Electromagnetic materials and devices. Intechopen. 2020, pp.1–20.

64.

Chung

DDL

. Electromagnetic interference shielding effectiveness of carbon materials. Carbon N Y 2001; 39: 279–285.

65.

Khan

SUD

Arora

Wahab

, et al. Permittivity and electromagnetic interference shielding investigations of activated charcoal loaded acrylic coating compositions. J Polym 2014; 2014: 1–7.

66.

González

Pozuelo

Baselga

Electromagnetic shielding materials in GHz range. Chem Rec 2018; 18: 1000–1009.

67.

Ahmad

Hussain

Nawab

, et al. Effect of dielectric and magnetic nanofillers on electromagnetic interference shielding effectiveness of carbon/epoxy composites. J Compos Mater 2022; 56: 69–82.

68.

Afilipoaei

Teodorescu-Draghicescu

A review over electromagnetic shielding effectiveness of composite materials. Multidiscip Digit Publ Inst 2020; 63: 23.

69.

Saini

Arora

Microwave absorption and emi shielding behavior of nanocomposites based on intrinsically conducting polymers, graphene and carbon nanotubes. In: De Souza Gomes

(ed.) New polymers for special applications. IntechOpen, 2012; 71–112. https://www.intechopen.com/books/3043

70.

Wang

Liao

Wan

, et al. Electromagnetic interference shielding materials: recent progress, structure design, and future perspective. J Mater Chem C 2022; 10: 44–72.

71.

Geetha

Satheesh Kumar

Rao

CRK

, et al. EMI shielding: Methods and materials—a review. J of Appl Polymer Sci 2009; 112: 2073–2086.

72.

Kondawar

Modak

PR.

Theory of EMI shielding. In: Joseph

Wilson

George

(eds.) Materials for potential EMI shielding applications. Elsevier Inc, 2020, pp.9–25.

73.

Tezel

Kavuşturan

Vandenbosch

, et al. Comparison of electromagnetic shielding effectiveness of conductive single jersey fabrics with coaxial transmission line and free space measurement techniques. Text Res J 2014; 84: 461–476.

74.

Batool

Bibi

Frezza

, et al. Benefits and hazards of electromagnetic waves, telecommunication, physical and biomedical : a review. Eur Rev Med Pharmacol Sci 2019; 23: 3121–3128.

75.

Chern

JT.

Effect of stainless steel-containing fabrics on electromagnetic shielding effectiveness. Text Res J 2004; 74: 51–54. https://doi.org/10.1177/004051750407400109

76.

Aquino

Holanda

Santos

, et al. Analysis of polymeric knitted fabrics on properties for telecommunications devices application. Fibers Polym 2019; 20: 2348–2354.

77.

Gupta

Abbas

Abhyankar

AC.

Ultra-lightweight hybrid woven fabric containing stainless steel/polyester composite yarn for total EMI shielding in frequency range 8–18 GHz. J Electromagn Waves Appl 2015; 29: 1454–1472.

78.

Bedeloglu

Investigation of electrical, electromagnetic shielding, and usage properties of woven fabrics made from different hybrid yarns containing stainless steel wires. J Text Inst 2013; 104: 1359–1373. https://doi.org/10.1080/00405000.2013.806049

79.

Lin

Jhang

Lin

, et al. Manufacturing techniques, mechanical properties, far infrared emissivity, and electromagnetic shielding effectiveness of stainless steel/polyester/bamboo charcoal knits. Fibers Polym 2017; 18: 597–604.

80.

Cheng

Hsiao

Road

Production and electromagnetic shielding effectiveness of the knitted stainless steel/polyester fabrics. J Textile Eng 2000; 46: 42–52.

81.

Ortlek

Alpyildiz

Kilic

Determination of electromagnetic shielding performance of hybrid yarn knitted fabrics with anechoic chamber method. Text Res J 2013; 83: 90–99.

82.

Gupta

Hybrid woven fabric for EMI shielding. J Fiber to Finish 2017; 56: 26–29.

83.

Lee

ML.

Electromagnetic shielding effectiveness of stainless steel polyester woven fabrics. Text Res J 2001; 71: 42–49.

84.

Wang

Pan

, et al. Analysis of shielding effectiveness in different kinds of electromagnetic shielding fabrics under different test conditions. Text Res J 2019; 89: 375–388. https://doi.org/10.1177/0040517517748490

85.

Erdumlu

Saricam

Electromagnetic shielding effectiveness of woven fabrics containing cotton/metal-wrapped hybrid yarns. J Ind Text 2016; 46: 1084–1103.

86.

Özkan

Telli

The effects of metal type, number of layers, and hybrid yarn placement on the absorption and reflection properties in electromagnetic shielding of woven fabrics. J Eng Fiber Fabr 2019; 14: 1–13.

87.

Lin

Huang

Lin

, et al. The process and property characteristic of electromagnetic shielding functional warp knitted composite fabrics. Adv Mater Res 2011; 287–290: 712–716.

88.

Kayacan Ö. The effect of washing processes on the electromagnetic shielding of knitted fabrics. Tekst ve Konfeksiyon 2014; 24: 356–362.

89.

Ahmed

Hussain

Ahmad

HS.

Advanced mesh knitted curtain fabric for electromagnetic interference shielding. J Eng Fibers Fabr 2025; 20: 1–14. https://doi.org/10.1177/15589250251319323

90.

Ceken

Ozkurt

The electromagnetic shielding properties of copper and stainless steel knitted fabrics. Tekstilec 2011; 60: 321–328.

91.

Ahmed

Hussain

Ahmad

HS.

Study of metal-based conductive knitted fabric enhanced with graphene/iron oxide nanoparticles, and metal-based ink. J Dispers Sci Technol 2025; 26: 4011–4020. https://doi.org/10.1007/s12221-025-01051-7

92.

Perumalraj

Dasaradan

Anbarasu

, et al. Electromagnetic shielding effectiveness of copper core-woven fabrics. J Text Inst 2009; 100: 512–524.

93.

Chen

Lee

Lin

, et al. Comparison of electromagnetic shielding effectiveness properties of diverse conductive textiles via various measurement techniques. J Mater Process Technol 2007; 192–193: 549–554.

94.

Hamed

Saeed

Mohammad

ES.

Investigating the electromagnetic shielding effectiveness of copper / cotton full Milano and 1 1 rib weft knitted fabrics. J Text Inst 2018; 110: 891–900.

95.

Ahmed

Hussain

Shehbaz Ahmad

Novel knitted fabric structures for shielding against electromagnetic and thermal radiation from laptops and mobile phones. Int J Therm Sci 2023; 194: 108594.

96.

Perumalraj

Dasaradan

BS.

Electromagnetic shielding effectiveness of copper core yarn knitted fabrics. Indian J Fibre Text Res 2009; 34: 149–154.

97.

Pamuk

Kayacan

, et al. Electromagnetic shielding effectiveness of carbon yarn-based woven fabrics. J Ind Text 2022; 51: 1143–1160.

98.

Ahmad

Hussain

Nawab

, et al. Effect of various dielectric and magnetic nanofillers on microwave absorption properties of carbon fiber reinforced composites structures. Ceram Int 2022; 48: 19882–19890.

99.

Wrobel

Knockaert

Mey

, et al. Shielding the electromagnetic waves by inserting conductive lightweight materials into woven curtains. J Fashion Technol Textil Eng 2018; s4: 1–4.

100.

Truhla

A new method and apparatus for evaluating the electromagnetic shielding effectiveness of textiles. Text Res J 2016; 86: 44–56. https://doi.org/10.1177/0040517515581587

101.

Krishnasamy

Ramasamy

Das

, et al. Effect of fabric cover and pore area distribution of carbon/stainless steel/polypropylene hybrid yarn-woven fabric on electromagnetic shielding effectiveness. J Electron Mater 2016; 45: 3087–3100. https://doi.org/10.1007/s11664-016-4391-y

102.

Pušić

Šaravanja

Malarić

Electromagnetic shielding properties of knitted fabric made from polyamide threads coated with silver. Materials 2021; 14: 12.

103.

Kenan Ceven

Ahmet Karakucuk

Emir Dirik

. Evaluation of electromagnetic shielding effectiveness of fabrics produced from yarns containing metal wire with a mobile based measurement system Evaluation of electromagnetic shielding effectiveness of fabrics produced. Ind Textila 2017; 68: 289–295. https://doi.org/10.35530/IT.068.04.1372

104.

Lou

Liu

Shiu

, et al. Preparation and evaluation of polyester-cotton/wire blended conductive woven fabrics for electromagnetic shielding. J Ind Text 2022; 51: 7104S–7118S. https://doi.org/10.1177/1528083721997184

105.

, et al. Functional properties and electromagnetic shielding behaviour of elastic warp-knitted fabrics. Fibres Text East Eur 2015; 23: 78–83.

106.

Marciniak

Grabowska

Stempień

, et al. Shielding of electromagnetic radiation by multilayer textile sets. Text Res J 2019; 89: 948–958.

107.

Taylor

Zhang

, et al. Determination of electromagnetic shielding and antibacterial properties of multifunctional warp- knitted fabrics. J Text Inst 2014; 106: 37–41.

108.

Tunakova

Tunak

Bajzik

, et al. Hybrid knitted fabric for electromagnetic radiation shielding. J Eng Fiber Fabr 2020; 15: 1–9.

109.

Castano

Flatau

. Effects of different conductive yarns’ knitting structure on electromagnetic shielding effectiveness. In: Aegean international textile and advanced engineering conference, 2018, p.459.

110.

Hwang

Chen

Lou

, et al. Electromagnetic shielding effectiveness and functions of stainless steel/bamboo charcoal conductive fabrics. J Ind Text 2014; 44: 477–494.

111.

Sancak

Akalin

Usta

, et al. The effects of fabric and conductive wire properties on electromagnetic shielding effectiveness and surface resistivity of interlock knitted fabrics. Fibers Polym 2018; 19: 843–853.

112.

Soyaslan

DD.

Investigation of the effect of conductive amount electromagnetic shielding performance in knitted fabrics. World J Text Eng Technol 2018; 4: 31–34.

113.

Asghar

Ahmad

Yahya

, et al. An alternative approach to design conductive hybrid cover yarns for efficient electromagnetic shielding fabrics. J Ind Text 2018; 48: 38–57.

114.

Ciesielska-wróbel

Grabowska

Estimation of the EMR shielding effectiveness of knit structures. Fibers Text East Eur 2012; 2: 53–60.

115.

Winterhalter

Teverovsky

Wilson

, et al. Development of electronic textiles to support networks, communications, and medical applications in future U.S. military protective clothing systems. IEEE Trans Inf Technol Biomed 2005; 9: 402–406.

116.

Maghrabi

Vijayan

Wang

, et al. Design of seamless knitted radiation shielding garments with 3d body scanning technology. Procedia Technol 2015; 20: 123–132.

117.

Taylor

Soyaslan

Çömlekçi

, et al. Determination of electromagnetic shielding performance of plain knitting and 1X1 rib structures with coaxial test fixture relating to ASTM D4935. J Text Inst 2010; 101: 37–41.

118.

Maity

Singha

Debnath

, et al. Textiles in electromagnetic radiation protection. J Saf Eng 2013; 2: 11–19.

119.

Abbas

Ahmad

Rashid

, et al. Thermal characterization of interlock structural hybridizations; de novo design approach for orchestrated performance. Therm Sci Eng Prog 2023; 38: 101658.

120.

Abdulla

Delihasanlar

Kizilcay Abdulla

, et al. Electromagnetic shielding characterization of conductive knitted fabrics. Prog Electromagn Res M 2017; 56: 33–41.

121.

Louris

Sfiroera

Priniotakis

, et al. Evaluating the ultraviolet protection factor (UPF) of various knit fabric structures. In: (UNIWA) U of WA (ed) Aegean International Textile and Advanced Engineering Conference, Mytilene, Lesvos island, Greece, 2018, p.5.

122.

Taylor

Çeken

Kayacan

, et al. The electromagnetic shielding properties of some conductive knitted fabrics produced on single or double needle bed of a flat knitting machine. J Text Inst 2011; 103: 37–41.

123.

Yin

Gao

, et al. A review of electromagnetic shielding fabric, wave-absorbing fabric and wave-transparent fabric. Polymers 2022; 14: 1–18.

124.

Xiao

Shi

Wang

, et al. The electromagnetic shielding and reflective properties of electromagnetic textiles with pores, planar periodic units and space structures. Text Res J 2014; 84: 1679–1691.

125.

Safarova

Militky

Lightweight and flexible structures for electromagnetic interference shielding-present state. In: 2015 38th International conference on telecommunications and signal processing, TSP 2015, 2015, pp.257–261.

126.

Ceken

Pamuk

Kayacan

, et al. Electromagnetic shielding properties of plain knitted fabrics containing conductive yarns. J Eng Fiber Fabr 2012; 7: 81–87.

127.

Rajendrakumar

Thilagavathi

A study on the effect of construction parameters of metallic wire/core spun yarn based knitted fabrics on electromagnetic shielding. J Ind Text 2013; 42: 400–416.

128.

Han

, et al. Processing and electromagnetic shielding properties of multifunctional metal composite knitted fabric used as socks. MATEC Web Conf 2016; 67: 0–5.

129.

Gokarneshan

Varadarajan

Sentil kumar

, et al. Engineering knits for versatile technical applications: some insights on recent researches. J Ind Text 2012; 42: 52–75.

130.

Zhu

XY.

Study on the warp and weft direction conductivity of anti-radiation knitted fabric. Sci Res Essays 2014; 9: 407–409.

131.

Mohamed

Ezzat

Abdel Megeid

, et al. Suitability of conductive knit fabric for sensing human breathing. J Sci Res Sci 2016; 33: 359–369.

132.

Palanisamy

Tunakova

Militky

Fiber-based structures for electromagnetic shielding – comparison of different materials and textile structures. Text Res J 2018; 88: 1992–2012.

133.

Kumar

Rosunee

Bradshaw

Measuring electromagnetic shielding efficiency of 1×1 plain knitted fabrics. Int J Clothing Sci Technol 2017; 29: 525–538.

134.

Palanisamy

Tunakova

Militky

, et al. Effect of moisture content on the electromagnetic shielding ability of non-conductive textile structures. Sci Rep 2021; 11: 110.

Human health and electromagnetic radiation: The role of knitted yarns,fabrics,and garments – a critical review

Abstract

Keywords

Introduction

Theoretical background

Knitted fabrics and their classification

Application of knitted fabric in technical textile

Electromagnetic radiation (EMR)

Effect of EMR on electronic equipment and human health

Infertility due to usage of laptop and mobile phones

Importance of (EMI) shielding

Mechanism of electromagnetic interference (EMI) shielding

Parameters of electromagnetic interference shielding effectiveness

Reflection loss

Multiple reflection

Absorption loss mechanism

Skin depth

Electrical conductivity and loss tangent

Loss tangent

Measurement techniques of EMI shielding

Literature review

EMI shielding materials used for fabric manufacturing

Effect of knitted structures on electromagnetic shielding effectiveness

Conclusion

Critical analysis and future directions

Footnotes

ORCID iD

Author contributions

Funding

Declaration of conflicting interests

Data Availability Statement

References