Microwave burns are burn injuries caused by thermal effects of microwave radiation absorbed in a living organism. In comparison with radiation burns caused by ionizing radiation, where the dominant mechanism of tissue damage is internal cell damage caused by free radicals, the primary damage mechanism of microwave radiation is by heat.
A burn is a type of injury to skin, or other tissues, caused by heat, cold, electricity, chemicals, friction, or radiation. Most burns are due to heat from hot liquids, solids, or fire. While rates are similar for males and females the underlying causes often differ. Among women in some areas, risk is related to use of open cooking fires or unsafe cook stoves. Among men, risk is related to the work environments. Alcoholism and smoking are other risk factors. Burns can also occur as a result of self harm or violence between people.
Injury, also known as physical trauma, is damage to the body caused by external force. This may be caused by accidents, falls, hits, weapons, and other causes. Major trauma is injury that has the potential to cause prolonged disability or death.
Microwaves are a form of electromagnetic radiation with wavelengths ranging from about one meter to one millimeter; with frequencies between 300 MHz (1 m) and 300 GHz (1 mm). Different sources define different frequency ranges as microwaves; the above broad definition includes both UHF and EHF bands. A more common definition in radio engineering is the range between 1 and 100 GHz. In all cases, microwaves include the entire SHF band at minimum. Frequencies in the microwave range are often referred to by their IEEE radar band designations: S, C, X, Ku, K, or Ka band, or by similar NATO or EU designations.
Microwave damage can manifest with a delay; pain or signs of skin damage can show some time after microwave exposure.
The depth of penetration depends on the frequency of the microwaves and the tissue type. The Active Denial System ("pain ray") is a less-lethal directed energy weapon that employs a microwave beam at 95 GHz; a two-second burst of the 95 GHz focused beam heats the skin to a temperature of 130 °F (54 °C) at a depth of 1/64th of an inch (0.4 mm) and is claimed to cause skin pain without lasting damage. Conversely, lower frequencies penetrate deeper; at 5.8 GHz (3.2 mm) the depth most of the energy is dissipated in the first millimeter of the skin; the 2.45 GHz frequency microwaves commonly used in microwave ovens can deliver energy deeper into the tissue; the generally accepted value is 17 mm for muscle tissue.
The Active Denial System (ADS) is a non-lethal, directed-energy weapon developed by the U.S. military, designed for area denial, perimeter security and crowd control. Informally, the weapon is also called the heat ray since it works by heating the surface of targets, such as the skin of targeted human subjects. Raytheon is currently marketing a reduced-range version of this technology. The ADS was deployed in 2010 with the United States military in the Afghanistan War, but was withdrawn without seeing combat. On August 20, 2010, the Los Angeles Sheriff's Department announced its intent to use this technology on prisoners in the Pitchess Detention Center in Los Angeles, stating its intent to use it in "operational evaluation" in situations such as breaking up prisoner fights. As of 2014, the ADS was only a vehicle-mounted weapon, though U.S. Marines and police were both working on portable versions. ADS was developed under the sponsorship of the DoD Non-Lethal Weapons Program with the Air Force Research Laboratory as the lead agency. There are reports that Russia and China are developing their own versions of the Active Denial System.
A microwave oven is an electric oven that heats and cooks food by exposing it to electromagnetic radiation in the microwave frequency range. This induces polar molecules in the food to rotate and produce thermal energy in a process known as dielectric heating. Microwave ovens heat foods quickly and efficiently because excitation is fairly uniform in the outer 25–38 mm(1–1.5 inches) of a homogeneous, high water content food item; food is more evenly heated throughout than typically occurs in other cooking techniques.
As lower frequencies penetrate deeper into the tissue, and as there are fewer nerve endings in deeper-located parts of the body, the effects of the radio frequency waves (and the damage caused) may not be immediately noticeable. The lower frequencies at high power densities present a significant risk.
The microwave absorption is directed by the dielectric constant of the tissue. At 2.5 GHz, this ranges from about 5 for adipose tissue to about 56 for the cardiac muscle. As the speed of electromagnetic waves is proportional to the reciprocal of the square root of the dielectric constant, the resulting wavelength in the tissue can drop to a fraction of the wavelength in air; e.g. at 10 GHz the wavelength can drop from 3 cm to about 3.4 mm.
In biology, adipose tissue, body fat, or simply fat is a loose connective tissue composed mostly of adipocytes. In addition to adipocytes, adipose tissue contains the stromal vascular fraction (SVF) of cells including preadipocytes, fibroblasts, vascular endothelial cells and a variety of immune cells such as adipose tissue macrophages. Adipose tissue is derived from preadipocytes. Its main role is to store energy in the form of lipids, although it also cushions and insulates the body. Far from being hormonally inert, adipose tissue has, in recent years, been recognized as a major endocrine organ, as it produces hormones such as leptin, estrogen, resistin, and the cytokine TNFα. The two types of adipose tissue are white adipose tissue (WAT), which stores energy, and brown adipose tissue (BAT), which generates body heat. The formation of adipose tissue appears to be controlled in part by the adipose gene. Adipose tissue – more specifically brown adipose tissue – was first identified by the Swiss naturalist Conrad Gessner in 1551.
Cardiac muscle is one of three types of vertebrate muscles, with the other two being skeletal and smooth muscles. It is an involuntary, striated muscle that constitutes the main tissue of the walls of the heart. The myocardium forms a thick middle layer between the outer layer of the heart wall and the inner layer, with blood supplied via the coronary circulation. It is composed of individual heart muscle cells (cardiomyocytes) joined together by intercalated discs, encased by collagen fibres and other substances that form the extracellular matrix.
The layers of the body can be approximated as a thin layer of epidermis, dermis, adipose tissue (subcutaneous fat), and muscle tissue. At dozens of gigahertz, the radiation is absorbed in the top fraction to top few millimeters of skin. Muscle tissue is a much more efficient absorber than fat, so at lower frequencies that can penetrate sufficiently deep, most energy gets deposited there. In a homogeneous medium, the energy/depth dependence is an exponential curve with the exponent depending on the frequency and tissue. For 2.5 GHz, the first millimeter of muscle tissue absorbs 11% of the heat energy, the first two millimeters together absorb 20%. For lower frequencies, the attenuation factors are much lower, the achievable heating depths are higher, and the temperature gradient within the tissue is lower.
The tissue damage depends primarily on the absorbed energy and the tissue sensitivity; it is a function of the microwave power density (which depends on the distance from the source and its power output), frequency, absorption rate in the given tissue, and the tissue sensitivity. Tissues with high water (resp. electrolyte) content show higher microwave absorption.
Power density is the amount of power per unit volume.
The degree of the tissue damage depends on both the achieved temperature and the length of exposure. For short times, higher temperatures can be tolerated.
The damage can be spread over a large area, when the source is a relatively distant energy radiator, or a very small (though possibly deep) area, when the body comes to a direct contact with the source (e.g. a wire or a connector pin).
The epidermis has high electrical resistance for lower frequencies; at higher frequencies, the energy penetrates through by capacitive coupling. Damage to epidermis has low extent unless the epidermis is very moist. The characteristic depth for lower-frequency microwave injury is about 1 cm. The heating rate of adipose tissue is much slower than of muscle tissue. Frequencies in millimeter wave range are absorbed in the topmost layer of skin, rich in thermal sensors. At lower frequencies, between 1–10 GHz, most of the energy is however absorbed in deeper layers; the threshold for cellular injury there lies at 42 °C while the pain threshold is at 45 °C, so a subjective perception may not be a reliable indicator of a harmful level of exposure at those frequencies.
Exposure to frequencies common in domestic and industrial sources rarely leads to significant skin damage; in such cases, the damage tends to be limited to upper limbs. Significant injury with erythema, blisters, pain, nerve damage and tissue necrosis can occur even with exposures as short as 2–3 seconds. Due to the deep penetration of these frequencies, the skin may be minimally affected and show no signs of damage, while muscles, nerves, and blood vessels may be significantly damaged. Sensory nerves are particularly sensitive to such damage; cases of persistent neuritis and compression neuropathy were reported after significant microwave exposures.
Microwave burns show some similarities with electrical burns, as the tissue damage is deep rather than superficial. Adipose tissue shows less degree of damage than muscles and other water-rich tissues. (In contrast, radiant heat, contact burns and chemical burns damage subcutaneous adipose tissue to higher extent than deeper muscle tissue.) Full-thickness biopsy of the area between burned and unburned skin shows layers of more and less damaged tissue ("tissue sparing"), layers of undamaged fat between damaged muscles; a pattern that is not present in conventional thermal or chemical burns. Cells subjected to electrical burns show microscopic nuclear streaming on histology examination; this feature is not present with microwave burns. Microwaves also deposit more energy to areas with low blood supply and to tissue interfaces.
Hot spots may be formed in the tissue, with a consequent higher absorption of microwave energy and even higher temperature achieved, with localized necrosis of the affected tissue following.Sometimes, the affected tissue can even be charred.
Muscle tissue destruction can lead to myoglobinuria, with renal failure following in severe cases; this is similar to burns from electric current. Urinalysis and serum CPK, BUN and creatine tests are used to check for this condition.
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Cases of severe conjunctivitis were reported after technicians looked into powered waveguides.
Microwave-induced cataracts have been reported.Experiments on rabbits and dogs, mostly in the UHF range of frequencies, shown that the ocular effects are confined to eyelids and conjuctiva (as e.g. anterior segment keratitis or iritis). Cataracts were observed at several workers exposed to radiofrequency radiation, but in some of the cases the cause was unrelated to the RF exposure and in the other cases the evidence was incomplete or inconclusive. Some sources however mention incidence of microwave-related injuries of ocular lens and retina and the possibility of thermal effects to cause cataracts or focal tissue burns (incl. keratitis).
For the near field 2.45 GHz frequency, the minimum power density to cause cataracts in rabbits was found to be 150 mW/cm2 for 100 minutes; a retrolental temperature of 41 °C was necessary to be achieved. When the eye temperature was kept low by external cooling, cataracts were not produced by higher field intensities; that supports the hypothesis of a thermal mechanism being involved.
Sensory nerves are particularly sensitive to microwave damage. Cases of persistent neuritis and compression neuropathy were reported after significant microwave exposures.
When the temperature of the brain is raised to or above 42 °C, the blood–brain barrier permeability increases.
A neuropathy due to peripheral nerve lesion, without visible external burns, can occur when the nerve is subjected to microwaves of sufficient power density. The damage mechanism is believed to be thermal. Radiofrequency waves and ultrasound can be used for temporary blocking of peripheral nerves during neurosurgical operations.
The thermal effects of microwaves can cause testicular degeneration and lower sperm count.
Pulmonary burn can be present when lungs are exposed; chest x-ray is used for diagnosing.
Exposure of abdomen may lead to bowel obstruction due to stenosis of the affected bowel; flat and upright abdominal x-ray is used to check for this condition.
Household microwave ovens have shielding around the inside of the oven that prevents microwaves from leaking out, as well as safety interlocks that prevent the oven from operating when the door is open. Therefore, burns due to direct exposure to microwave energy (as opposed to touching hot food) should not occur under normal circumstances.
There are several cases of child abuse where an infant or child has been placed in a microwave oven. The typical feature of such injuries are well-defined burns on the skin nearest to the microwave emitter, and histology examination shows higher damage extent in tissues with high content of water (e.g., muscles) than in tissues with less water (e.g., adipose tissue).
One such case involved a teenage babysitter who admitted to having placed a child in the microwave oven for approximately sixty seconds. The child developed a third degree burn to the back, measuring 5 inches x 6 inches. The babysitter later took the child to the emergency department, where multiple skin grafts were placed on the back. There were no signs of lasting emotional, cognitive or physical effects. CT scan of the head was normal, and there were no cataracts.
Another case involved a five-week-old female infant that had multiple full-thickness burns totaling 11% of the body surface area. The mother claimed the infant had been near a microwave oven, but not inside it. The infant survived but required amputations of parts of one leg and one hand.
Also, there have been three alleged infant deaths caused by microwave ovens.In all these cases, the babies were placed within microwaves and died of subsequent injuries.
A case of nerve damage by an exposure to radiation from a malfunctioning 600 watt microwave oven, operated for five seconds with the door open, with both arms and hands exposed, was reported. During exposure, there was a pulsating, burning sensation in all fingers. Erythema appeared on the back sides of both hands and arms. Four years later, denervation of median nerve, ulnar nerve, and radial nerve in both arms was shown on an electromyography test.
The first microwave oven injury was reported in 1973. Two women operated a microwave oven in a department store snack bar. After several years, the oven showed a malfunction manifesting by burning the food. The first woman noticed burning sensations in her fingers and very little pain or tenderness when nearby to the operating oven. A small lesion appeared on her left index finger, near the base of the fingernail. In the next four weeks, three fingers of her right hand became affected as well. Transverse ridging and deformations close to the nail base appeared on her fingernails. After five months since the initial symptoms, she visited a doctor; the examination found no abnormalities other than the nails. Topical steroid cream used over six weeks led to gradual improvement. The second woman experienced nail deformation at the same time as the first one, with the same clinical findings. The oven was returned to the manufacturer before the involvement of the doctor, and the amount of leakage could not be assessed.
On July 29, 1977, H.F., a 51-year-old teacher, was attempting to remove a casserole dish from her new 600-watt microwave oven. The oven signaled the end of the heating cycle, but the light and the cooking blower were on. During retrieval of the dish, she inserted two thirds of her bare forearms into the oven, for a total time of about five seconds. The oven was still operating. She felt "hot pulsating sensation" and burning in fingers and fingernails and a sensation of "needles" over the exposed areas. Jabbing pain, swelling, and red-orange discoloration of dorsal sides of both hands and forearms appeared shortly afterwards. The next day she sought medical help. Since then, she has undergone treatment with oral and topical cortisone, Grenz rays, ultrasound, and later acupuncture, without relief. Symptoms persisted, including high sensitivity to radiant heat (sun, desk lamp, etc.) and growing intolerance to pressure of clothes and to touch in hands and forearms. Neurological examinations in 1980 and 1981 did not yield a definite diagnosis. Neuronal latencies were within norm. Electromyography discovered denervation in the median nerve, ulnar nerve, and radial nerve on both arms. Severe reduction of number of sweat glands in the finger pulps, in comparison with a random control, was also found. The injury was determined to be caused by the full power of the magnetron; the pulsating sensation was caused either by the stirrer (a mechanical mirror distributing the microwave beam across the oven space to prevent formation of hot and cold spots), or by the arterial pulsation in combination with increased nerve sensitivity. Damage to the A beta fibers, A delta fibers, and group C nerve fibers was the cause of the burning sensation. The increased hypersensitivity to radiant heat is caused by the damage to the A beta, A delta, and polymodal nociceptors (the group C fibers); this damage is induced by a single-time overheating of the skin to 48.5–50 °C, and the resulting sensitivity persists for a long time. Degeneration of the alpha motor neurons is also caused by the exposure to heat and radiation. Most of the major nerve trunks were not affected. Damage to the A beta fibers (located in the skin), discovered by the two-point discrimination test, is permanent; the Pacinian corpuscles, Meissner corpuscles, and Merkel nerve endings, which degenerated after denervation, do not regenerate. The sympathetic nervous system was involved as well; the reduction in active sweat glands was caused by destruction of their innervation, the initial edema and reddening was also caused by sympathetic nerve damage.
In 1983, a 35-year-old male was heating a sandwich in a microwave oven at work. After opening the door, the magnetron did not shut off and his right hand was exposed to microwave radiation as he retrieved the sandwich. After exposure, his hand was pale and cold; 30 minutes later the man presented himself to a doctor, with paresthesia in all fingers and the hand still pale and cold. An Allen's test showed a return to normal color after 60 seconds (normal is 5 seconds). By 60 minutes after exposure the hand was normal again, and the patient was discharged without treatment. A week later there was no paresthesia, motor weakness nor sensory deficit.
An engineer replaced a woodpecker-damaged feed horn of a high-power microwave antenna, a 15-meter dish at an Earth station of a television network, using a cherry picker. After finishing, he sent his technician to power up the transmitter, and attempted to lower the cherry picker down. The engine failed and the engineer was stuck next to the antenna, outside of its main lobe but well within the first sidelobe. The technician, unaware that the engineer was still close to the antenna, powered it up. The engineer was exposed to an intense microwave field for about three minutes, until the error was realized. There were no immediate symptoms; the next morning the engineer detected blood and solid matter in his urine, and visited a doctor, who found blood in stool and massive bowel adhesions. The engineer's medical problems lasted for many years.
Dielectric heating (diathermy) is used in medicine; the frequencies used typically lie in the ultrasonic, shortwave, and microwave ranges. Careless application, especially when the patient has implanted metal conductors (e.g. cardiostimulator leads), can cause burns of skin and deeper tissues and even death.
Microwave damage to tissues can be intentionally exploited as a therapeutic technique, e.g. radiofrequency ablation and radiofrequency lesioning. Controlled destruction of tissue is performed for treatment of arrhythmia.Microwave coagulation can be used for some kinds of surgeries, e.g., stopping bleeding after a severe liver injury.
Microwave heating seems to cause more damage to bacteria than equivalent thermal-only heating.However food reheated in a microwave oven typically reaches lower temperature than classically reheated, therefore pathogens are more likely to survive.
Microwave heating of blood, e.g. for transfusion, is contraindicated, as it can cause hemolysis and hyperkalemia.
Microwave heating is one of the methods for inducing hyperthermia for hyperthermia therapy.
High-energy microwaves are used in neurobiology experiments to kill small laboratory animals (mice, rats) in order to fix brain metabolites without the loss of anatomical integrity of the tissue. The instruments used are designed to focus most of the power to the animal's head. The unconsciousness and death is nearly instant, occurring in less than one second, and the method is the most efficient one to fix brain tissue chemical activity. A 2.45 GHz, 6.5 kW source will heat the brain of a 30 g mouse to 90 °C in about 325 milliseconds; a 915 MHz, 25 kW source will heat the brain of a 300 g rat to the same temperature in a second. Special devices designed or modified for this purpose have to be used; use of kitchen-grade microwave ovens is condemned.
Safety limits exist for microwave exposure. The U.S. Occupational Safety and Health Administration defines energy density limit for exposure periods of 0.1 hours or more to 10 mW/cm2; for shorter periods the limit is 1 mW-hr/cm2 with limited excursions above 10 mW/cm2. The U.S. Food and Drug Administration (FDA) standard for microwave oven leakage puts limit to 5 mW/cm2 at 2 inches from the oven's surface.
For 5.8 GHz, exposure to 30 mW/cm2 causes increase of facial skin temperature by 0.48 °C, corneal surface heats by 0.7 °C, and the temperature of retina is estimated to increase by 0.08–0.03 °C.
Exposure of skin to microwaves can be perceived as a sensation of heat or pain. Due to lower penetration of higher frequencies, perception threshold is lower for higher frequencies as more energy is dissipated closer to the body surface. When the entire face is exposed to 10 GHz microwaves, the feeling of heat is evoked at energy densities of 4–6 mW/cm2 for 5 or more seconds, or about 10 mW/cm2 for a half second. Experiments on six volunteers exposed to 2.45 GHz microwaves shown perception thresholds on forearm skin to be at the average of 25–29 mW/cm2, ranging from 15.40 to 44.25 mW/cm2. The sensation was indistinguishable from heat delivered by infrared radiation, though the infrared radiation required about five times lower energy density. Pain threshold for 3 GHz was demonstrated to range from 0.83–3.1 W/cm2 for 9.5 cm2 of exposed area, depending on length of the exposure; other source says the dependence is not directly on the power density and exposure length, but primarily on the critical skin temperature.
Microwave energy can be focused by metal objects in the vicinity of the body or when implanted. Such focusing and resultant increased heating can significantly lower the perception, pain and damage thresholds. Metal-framed glasses perturb microwave fields between 2–12 GHz; individual components were found to be resonant between 1.4 and 3.75 GHz.
A security guard with a metal plate in his leg experienced heating of the plate when patrolling near tropospheric scatter transmitter antennas; he had to be removed from their vicinity.
In the 30–300 GHz band, dry clothing may serve as an impedance transformer, facilitating more efficient energy coupling to the underlying skin.
Pulsed microwave radiation can be perceived by some workers as a phenomenon called "microwave hearing"; the irradiated personnel perceive auditory sensations of clicking or buzzing. The cause is thought to be thermoelastic expansion of portions of auditory apparatus. MHz to at least 3 GHz. In the tests, repetition rate of 50 Hz was used, with pulse width between 10–70 microseconds. The perceived loudness was found to be linked to the peak power density instead of average power density. At 1.245 GHz, the peak power density for perception was below 80 mW/cm2. The generally accepted mechanism is rapid (but minuscule, in the range of 10−5 °C) heating of brain by each pulse, and the resulting pressure wave traveling through skull to cochlea.The auditory system response occurs at least from 200
Some vacuum tubes present in microwave installations tend to generate bremsstrahlung x-rays. Magnetrons and especially hydrogen thyratrons tend to be the worst offenders.
As the energy of radio frequency waves and microwaves is insufficient to directly disrupt individual chemical bonds in small or stable molecules, the effects are considered limited to thermal. Energy densities that are not sufficient to overheat the tissues are not shown to cause lasting damage[ citation needed ]. To clarify, the deep-red lightbulb in a black-and-white photographic darkroom produces a higher-energy form of radiation than microwaves. Like a microwave, this lightbulb can burn, particularly if touched, but the burn is only possible due to too much heat. A study of 20,000 radar technicians of the US Navy, who were chronically exposed to high levels of microwave radiation, did not detect increased incidence of cancer. Recent epidemiologic evidence also led to the consensus that exposure to electromagnetic fields, e.g. along power lines, did not raise incidence of leukemia or other cancers.
A common myth among radar and microwave communication workers is that the exposure of the genital area to microwaves renders a man sterile for about a day. The power density necessary for this effect is however sufficient to also cause permanent damage.
The electromagnetic spectrum is the range of frequencies of electromagnetic radiation and their respective wavelengths and photon energies.
In physics, radiation is the emission or transmission of energy in the form of waves or particles through space or through a material medium. This includes:
At sufficiently high flux levels, various bands of electromagnetic radiation have been found to cause deleterious health effects in people. Electromagnetic radiation can be classified into two types: ionizing radiation and non-ionizing radiation, based on the capability of a single photon with more than 10 eV energy to ionize oxygen or break chemical bonds. Extreme ultraviolet and higher frequencies, such as X-rays or gamma rays are ionizing, and these pose their own special hazards: see radiation and radiation poisoning. The last quarter of the twentieth century saw a dramatic increase in the number of devices emitting non-ionizing radiation in all segments of society, which resulted in an elevation of health concerns by researchers and clinicians, and an associated interest in government regulation for safety purposes. In the United States, this has resulted in legislation such as the Radiation Control for Health and Safety Act of 1968 and the Occupational Safety and Health Act of 1970. By far the most common health hazard of radiation is sunburn, which causes over one million new skin cancers annually in United States.
Radio frequency (RF) is the oscillation rate of an alternating electric current or voltage or of a magnetic, electric or electromagnetic field or mechanical system in the frequency range from around twenty thousand times per second to around three hundred billion times per second. This is roughly between the upper limit of audio frequencies and the lower limit of infrared frequencies; these are the frequencies at which energy from an oscillating current can radiate off a conductor into space as radio waves. Different sources specify different upper and lower bounds for the frequency range.
The microwave auditory effect, also known as the microwave hearing effect or the Frey effect, consists of the human perception of audible clicks, or even speech, induced by pulsed or modulated radio frequencies. The communications are generated directly inside the human head without the need of any receiving electronic device. The effect was first reported by persons working in the vicinity of radar transponders during World War II. In 1961, the American neuroscientist Allan H. Frey studied this phenomenon and was the first to publish information on the nature of the microwave auditory effect. The cause is thought to be thermoelastic expansion of portions of the auditory apparatus, although competing theories explain the results of holographic interferometry tests differently.
Radio waves are a type of electromagnetic radiation with wavelengths in the electromagnetic spectrum longer than infrared light. Radio waves have frequencies as high as 300 gigahertz (GHz) to as low as 30 hertz (Hz). At 300 GHz, the corresponding wavelength is 1 mm, and at 30 Hz is 10,000 km. Like all other electromagnetic waves, radio waves travel at the speed of light. They are generated by electric charges undergoing acceleration, such as time varying electric currents. Naturally occurring radio waves are emitted by lightning and astronomical objects.
A microwave radiometer (MWR) is a radiometer that measures energy emitted at millimetre-to-centimetre wavelengths known as microwaves. Microwave radiometers are very sensitive receivers designed to measure thermal electromagnetic radiation emitted by atmospheric gases. They are usually equipped with multiple receiving channels in order to derive the characteristic emission spectrum of the atmosphere or extraterrestrial objects. Microwave radiometers are utilized in a variety of environmental and engineering applications, including weather forecasting, climate monitoring, radio astronomy and radio propagation studies.
Diathermy is electrically induced heat or the use of high-frequency electromagnetic currents as a form of physical therapy and in surgical procedures. The earliest observations on the reactions of high-frequency electromagnetic currents upon the human organism were made by Jacques Arsene d'Arsonval. The field was pioneered in 1907 by German physician Karl Franz Nagelschmidt, who coined the term diathermy from the Greek words dia and θέρμη therma, literally meaning "heating through".
A heating pad is a pad used for warming of parts of the body in order to manage pain. Localized application of heat causes the blood vessels in that area to dilate, enhancing perfusion to the targeted tissue. Types of heating pads include electrical, chemical and hot water bottles.
Dielectric heating, also known as electronic heating, radio frequency heating, and high-frequency heating, is the process in which a radio frequency (RF) alternating electric field, or radio wave or microwave electromagnetic radiation heats a dielectric material. At higher frequencies, this heating is caused by molecular dipole rotation within the dielectric.
A radiation burn is damage to the skin or other biological tissue as an effect of radiation. The radiation types of greatest concern are thermal radiation, radio frequency energy, ultraviolet light and ionizing radiation.
Bioelectromagnetics, also known as bioelectromagnetism, is the study of the interaction between electromagnetic fields and biological entities. Areas of study include electrical or electromagnetic fields produced by living cells, tissues or organisms, including bioluminescent bacteria; for example, the cell membrane potential and the electric currents that flow in nerves and muscles, as a result of action potentials. Others include animal navigation utilizing the geomagnetic field; the effects of man-made sources of electromagnetic fields like mobile phones; and developing new therapies to treat various conditions. The term can also refer to the ability of living cells, tissues, and organisms to produce electrical fields and the response of cells to electromagnetic fields.
Electrosurgery is the application of a high-frequency alternating polarity, electrical current to biological tissue as a means to cut, coagulate, desiccate, or fulgurate tissue.. Its benefits include the ability to make precise cuts with limited blood loss. Electrosurgical devices are frequently used during surgical operations helping to prevent blood loss in hospital operating rooms or in outpatient procedures.
Heat therapy, also called thermotherapy, is the use of heat in therapy, such as for pain relief and health. It can take the form of a hot cloth, hot water bottle, ultrasound, heating pad, hydrocollator packs, whirlpool baths, cordless FIR heat therapy wraps, and others. It can be beneficial to those with arthritis and stiff muscles and injuries to the deep tissue of the skin. Heat may be an effective self-care treatment for conditions like rheumatoid arthritis.
Susceptor is the name of a material used for its ability to absorb electromagnetic energy and convert it to heat. The electromagnetic energy is typically radiofrequency or microwave radiation used in industrial heating processes, and also in microwave cooking. The name is derived from susceptance, an electrical property of materials that measures their tendency to convert electromagnetic energy to heat.
Hyperthermia therapy is a type of medical treatment in which body tissue is exposed to higher temperatures in an effort to treat cancer.
Non-ionizingradiation refers to any type of electromagnetic radiation that does not carry enough energy per quantum to ionize atoms or molecules—that is, to completely remove an electron from an atom or molecule. Instead of producing charged ions when passing through matter, non-ionizing electromagnetic radiation has sufficient energy only for excitation, the movement of an electron to a higher energy state. Ionizing radiation which has a higher frequency and shorter wavelength than nonionizing radiation, has many uses but can be a health hazard; exposure to it can cause burns, radiation sickness, cancer, and genetic damage. Using ionizing radiation requires elaborate radiological protection measures which in general are not required with nonionizing radiation.