US20110030113A1

US20110030113A1 - Preventing Traumatic Brain Injury

Info

Publication number: US20110030113A1
Application number: US12/536,927
Authority: US
Inventors: Timothy J. Imholt; John L. Tomich; Julius F. Bogdanowicz
Original assignee: Raytheon Co
Current assignee: Raytheon Co
Priority date: 2009-08-06
Filing date: 2009-08-06
Publication date: 2011-02-10

Abstract

According to one embodiment, a helmet is adapted to be worn on the head of a human wearer. An absorbing layer is adjacent to the helmet. The absorbing layer is configured to absorb at least a portion of a radio-frequency (RF) electromagnetic pulse. This RF electromagnetic pulse may originate from an explosion event, such as detonation of an Improvised Explosive Device (IED).

Description

TECHNICAL FIELD

This invention relates generally to the field of content management systems and more specifically to generating modified schemas.

BACKGROUND

A helmet is a form of protective gear worn on the head to protect it from injuries. The oldest use of helmets was by Ancient Greek soldiers, who wore thick leather or bronze helmets to protect the head from sword blows and arrows. Goggles are forms of protective eyewear that may enclose or protect the eye area in order to prevent objects, particulates, water or chemicals from striking the eyes. The Eskimos carved goggles from caribou antler, as well as wood and shell, to prevent snow blindness.

SUMMARY OF THE DISCLOSURE

According to one embodiment, a helmet is adapted to be worn on the head of a human wearer. An absorbing layer is adjacent to the helmet. The absorbing layer is configured to absorb at least a portion of a radio-frequency (RF) electromagnetic pulse. This RF electromagnetic pulse may originate from an explosion event, such as detonation of an Improvised Explosive Device (IED).
Certain embodiments of the invention may provide one or more technical advantages. A technical advantage of one embodiment may include the capability to reduce the probability of traumatic brain injury following an explosion event. A technical advantage of one embodiment may also include the capability to reduce the severity of brain injuries following an explosion event. A technical advantage of one embodiment may also include the capability to protect a human's eyes, ears, and cranium from radiation following an explosion event.
Various embodiments of the invention may include none, some, or all of the above technical advantages. One or more other technical advantages may be readily apparent to one skilled in the art from the figures, descriptions, and claims included herein.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention and its features and advantages, reference is now made to the following description, taken in conjunction with the accompanying drawings, in which:

FIG. 1 shows a table explaining how pressure is affected by volume, temperature, and amount of gas, according to the ideal gas law;

FIG. 2 illustrates the overpressure and underpressure regions of a blast wave as a function of time;

FIG. 3 shows a protection system according to one embodiment;

FIG. 4 shows a pair of protective goggles according to one embodiment;

FIG. 5 shows a face mask according to one embodiment; and

FIG. 6 shows an example protection system featuring elements from FIGS. 3-5.

DETAILED DESCRIPTION OF THE DRAWINGS

It should be understood at the outset that, although example implementations of embodiments of the invention are illustrated below, the present invention may be implemented using any number of techniques, whether currently known or not. The present invention should in no way be limited to the example implementations, drawings, and techniques illustrated below. Additionally, the drawings are not necessarily drawn to scale.
Since the start of Operation Iraqi Freedom (OIF) and Operation Enduring Freedom (OEF), Improvised Explosive Devices (IEDs) have been responsible for a greater number of injuries than any other kind of weapon. American forces have responded by providing additional armor protection on previously unarmored vehicles. In addition, armor may be required for many types of troops that were previously unexposed to combat situations.
In addition to an increased number of casualties, IEDs have caused injuries that have never before been considered due to increases in efficient armor systems, which allow soldiers to be closer to these bombs than ever before and survive. One example of such an injury is a traumatic brain injury (TBI). Traumatic brain injuries are caused by a variety of mechanisms with little or no protection being fielded today. Accordingly, teachings of certain embodiments recognize the ability to provide protection mechanisms that prevent TBI.

Traumatic Brain Injury

Traumatic brain injuries are injuries to the brain. TBIs are sometimes called intracranial injuries, or more simply, head injuries. TBI occurs in the civilian world all the time by people hitting their heads and suffering a concussion.
The cost of treating TBI patients varies wildly depending on the extent of the injury. A Harvard medical school study shows that, over a lifetime, a patient suffering from the range of TBI typical in a military environment may accrue from $500,000 to $10,000,000, in medical expenses over the life of the patient. Although this is merely a monetary value, one should not forget the human factor cost as well.
There are two subsets of TBI: closed head injuries and penetrating head injuries. A closed injury occurs when the skull is not breached, while a penetrating injury occurs when an object pierces the skull and enters the brain. In a combat environment, penetrating injuries are easy to diagnose quickly. However, closed head injuries are not always easy to diagnose, and some symptoms may not be immediately evident (some symptoms are). The more obvious symptoms may not manifest for days to weeks, and soldiers may be sent back out into the field while suffering from some sort of TBI symptom. For example, one symptom of TBI is delayed reaction time, which could be fatal to a soldier who is redeployed into a combat situation.
Head injuries can be subdivided into mild, moderate and severe TBI to help predict long-term outcome of the patient. One common classification is based on the Glasgow Coma Scale and duration of post-traumatic amnesia (PTA) and loss of consciousness (LOC). Prognosis for the patient worsens with the severity of injury, but mild TBI is more poorly defined and prognosis is not as generally clear.
With mild TBI, the patient may not even lose consciousness immediately following injury, or the patient may only lose consciousness for a few seconds. For mild TBI, the symptoms include, but are not limited to:

- Decreased reaction time
- Decreased coordination
- Trouble with memory
- Difficulty concentrating
- Changes in personality, behavioral, or mood
- Changes in sleep pattern
- Fatigue or lethargy
- Continued bad taste in mouth
- Continued ringing in the ears
- Double vision, blurred vision
- Dizziness
- Mental Confusion
- Chronic Headaches

Mild TBI is also commonly called a concussion. Recovery rates for concussion are usually very good; a portion of people may suffer lasting problems associated with the injury, such as post-concussion syndrome. A patient who receives a second or third concussion before symptoms have healed from the first is at risk for developing a very rare but deadly condition called second-impact syndrome in which the brain swells catastrophically even after a mild blow.
With moderate or severe TBI, the patient may never fully recover from the sustained injuries. The patient may show all the same symptoms as with mild TBI. Additional TBI symptoms may include:

- Loss of consciousness
- Personality change
- Severe, persistent or worsening headache
- Repeated vomiting or nausea
- Seizures
- Dilation of Pupils
- Slurred Speech
- Weakness or numbness in extremities
- Loss of coordination
- Increased confusion, restlessness or agitation
- Abnormal posturing
- Vomiting
- Loss of motor skills
- Loss of memory
- Loss of cognitive skills

In some cases, the damage from TBI may be confined to just one area of the brain; in others, TBI damage may be spread over a larger portion. TBI damage caused by IED explosions tends to be localized behind the eyes and ears in the skull. Behind the eyes and the ears the human anatomy has either no bone or a much different kind of bone, allowing TBI damage to penetrate further.
Diffuse trauma to the brain is usually associated with concussion or coma. Localized injuries may be associated with neurobehavioral manifestations, hemiparesis, or other focal neurologic deficits. Types of focal brain injury may include bruising of brain tissue (a contusion) and intracranial hemorrhage or hematoma (heavy bleeding inside the skull without any external physical manifestations). Hemorrhage due to rupture of a blood vessel in the head can be extra-axial (meaning within the skull but outside the brain) or intra-axial (occurring within the brain). Extra-axial hemorrhages may also include subdural hematoma, which involves bleeding into the area between the skull and the dura.
Unlike most forms of traumatic death, a large percentage of the people killed by TBI do not die right away, but instead linger for days to weeks after the event. Some patients do improve after being hospitalized; however, approximately forty percent of TBI patients deteriorate. Primary injury is not adequate to explain this degeneration. Rather, the deterioration is caused by secondary injury, a set of biochemical cascades that occur in the minutes to days following the trauma and contribute to morbidity and mortality from these injuries. These secondary injury events are poorly understood form a medical perspective but are thought to include brain-swelling, alterations in cerebral blood flow, a decrease in the tissues pH, free radical overload, and exitocity. These secondary processes damage neurons that were not directly harmed by the primary injury.
The results of a traumatic brain injury in a patient vary widely in type and duration. A patient may experience physical effects in the trauma such as headaches, movement disorders (like during Parkinson's), seizures, difficulty walking, sexual dysfunction, lethargy or coma. Cognitive symptoms include changes in judgment or ability to reason or plan, memory problems, and in many patients loss of mathematical ability. Emotional problems include mood swings, poor impulse control, agitation, low frustration threshold, self-centeredness, clinical depression, hallucinations and delusions.
According to the AMA there are six abnormal states of consciousness that can result from a TBI, these include: stupor, coma, persistent, vegetative state, minimally conscious state, locked-in syndrome, and brain death.
There are many health complications that may occur in the period immediately following a TBI. The risk of these complications being seen in a patient increases with the severity of the trauma. These complications include: seizures, hydrocephalus (post-traumatic ventricular enlargement), cerebrospinal fluid leaks, infections, vascular injuries, and criminal nerve injuries. Pain, in the form of headaches, is a very common complication following a TBI. Serious complications may include pressure sores of the skin, pneumonia, and progressive multiple organ failure.
Disabilities resulting from TBI depend on the severity of the injury, location of injury, age and general health of the patient. Common disabilities include problems such as:

- Cognition
  - Attention
  - Calculation
  - Memory
  - Judgment
  - Insight
  - Reasoning
- Sensory processing
  - Sight
  - Hearing
  - Touch
  - Taste
  - Smell
- Communication
  - Language expression
  - Understanding
- Social function
  - Empathy
  - Capacity for compassion
  - Interpersonal social awareness
- Mental health
  - Depression
  - Anxiety
  - Personality changes
  - Aggression
  - Acting out
  - Social inappropriateness

The cognitive disabilities resulting from TBI may be especially troublesome, as TBI can cause cognitive disabilities including the permanent loss of higher-level mental skills. Memory loss occurs in 20-80% of people with closed head trauma depending on the severity of the injury.
Patients with mild to moderate head injuries may become easily confused or distracted and have problems with concentration and attention. They may also have problems with higher-level executive functions such as planning, organizing, abstract reasoning, problem solving, and making judgments. These symptoms may make it difficult to resume pre-injury activities. Recovery from cognitive deficits is greatest within the first six months and more gradual to non-existent after that.
Patients with moderate to severe TBI have more problems with cognitive deficits than patients with mild TBI. However a history of several mild TBIs may have an additive or multiplicative effect.
Language and communication problems are common disabilities in TBI patients. Some may experience aphasia, defined as difficulty with understanding and producing spoken and written language. Other patients may have difficulty with the more subtle aspects of communication, such as body language and emotional, non-verbal signals. TBI patients may have problems with spoken language if the part of the brain that controls speech muscle control is damaged.
Many TBI patients have sensory problems, especially associated with vision. Patients may not be able to register what they are seeing or may be slow to recognize objects. TBI patients often have difficulty with hand-eye coordination. Poor hand-eye coordination could be especially problematic of soldiers who must be able to shoot and hit targets during combat situations. Because of this these patients during recovery may be clumsy or unsteady. Other sensory deficits may include problems with hearing, smell, taste or touch. Some TBI patients develop tinnitus, a ringing or roaring in the ears. A person with damage to the part of the brain that controls the sense of touch may cause a TBI patient to develop persistent skin tingling, itching, or pain. These conditions are very hard to treat.
TBI may cause emotional or behavior problems, including personality changes. These may also fall under the category of psychiatric health. These problems may persist for one half year to two years after the injury and may include irritability, suicidal thoughts, insomnia, and loss of the ability to experience pleasure from previously enjoyable experiences. Other problems in this regard may include apathy, anxiety, anger, paranoia, confusion, frustration, agitation, and mood swings. One quarter of people with TBI may suffer from clinical depression. Additionally, as many as 50% of patients with penetrating head injuries may develop post-traumatic seizures. People with early seizures, those occurring within a week of injury, have an increased risk of post-traumatic epilepsy.
Medical personnel assess the patient's conditions by measuring vital signs and reflexes through a neurological examination. They assess the patient's level of consciousness and neurological functioning using various measurement scales.
Imaging tests are vital in determining the diagnosis and prognosis of a TBI patient. For moderate to severe cases, a computed tomography (CT) scan may be used. A CT scan creates a series of cross-sectional x-ray images of the head and brain. CT scans can show abnormalities such as bone fractures, hemorrhage, hematosis, contusions, brain tissue swelling and tumors. In addition, medical practitioners may use magnetic resonance imaging (MRI), which can show more detail than x-rays or CT scans. Although CT scans and MRI technology are in wide use in TBI diagnosis, other imaging techniques are commonly used as confirmation techniques.
Medical treatment usually begins with first responders or emergency medical technicians arriving on the scene of the occurrence of the injury. There is very little that can be done to reverse the initial brain damage caused by the trauma; thus, medical personnel try to stabilize the patient and focus on the prevention of further trauma. Primary treatment may include simple procedures such as insuring proper oxygen supply, maintaining adequate blood flow, and controlling blood pressure.
Sometimes when the brain is injured, swelling occurs and fluids accumulate within the space in which the brain is contained. When an injury occurs inside the skull-encased brain, there is very little if any place for the swollen tissues to expand and no adjoining tissues to absorb excess fluid. This leads to an increase in pressure within this skull. This is called intracranial pressure (ICP). High ICP can cause delicate brain tissue to be crushed or parts of the brain to literally herniate across the structures within the skull. This herniatiation can lead to severe damage.
During the acute stage of rehabilitation, moderately to severely injured patients may receive treatment and care in an intensive care unit of a hospital followed by movement to a step down unit or to a neurosurgical ward. Once medically stable, the patient may be transferred to a long-term acute care facility.
After discharge from the inpatient rehabilitation treatment unit, the outpatient phase of care begins. Goals often will shift from assisting the person to achieve independence in basic routines of daily living to treating broader psychosocial issues associate with long-term adjustment and community reintegration. An additional goal of the rehab program for these patients may include prevention of further medical complications.

The Explosive Sequence of an IED

In the war on terror, one of the primary threats facing troops is the IED. IEDs present new and complex mechanisms for harming soldiers. These include shrapnel, heat, electromagnetic pulse, and blast pressure, all of which will be discussed briefly below. But first, an explanation of the initiation of these threats (explosions) will be given.

Explosions Generally

An explosion is a rapid increase in volume and rapid release of energy. This will be accompanied by:

- Generation of high temperatures
- Release of gas
- High pressure zones
- Electromagnetic pulse
- Shrapnel at high speeds.

Usual explosives are chemical in nature are typically oxidation reactions. There are many non-chemical types of explosives; however, to date only chemical explosives have been seen in IEDs. Teachings of certain embodiments recognize the importance of protecting soldiers from each of the signatures seen from these devices. Teachings of certain embodiments also recognize that protection may be configured for each mission based on the type of IED known in the area, as well as the frequency of their occurrence.

Shrapnel

Bullets are not the only threat that must be designed into our military armor's ability to protect soldiers. We must also be concerned with shrapnel, such as from IED explosions. Shrapnel is a term used to describe metal fragments and debris thrown by an exploding device such as a roadside bomb.
The physics of bullet and shrapnel fight are inherently different, and one design of armor sufficient to stop a bullet may not necessarily stop shrapnel. The ease of stopping a bullet comes from its symmetry. If the penetration mechanics is known beforehand, armor can be designed to that penetration mechanics. In the case of shrapnel, the projectile can take on any shape and size. Accordingly, symmetry tricks may not necessarily be used in the protection of soldiers. These pieces of shrapnel can be any shape, weigh upwards of kilograms, and move at several times the speed of sound, making them incredibly energetic. This energy must be dissipated in such a way as to not only stop penetration and puncture wounds but also limit the level of blunt trauma that occurs where the piece of shrapnel has struck. In other words, if the blunt trauma is sufficient to cause fatal injury, no amount of armor protecting from puncture wounds will prevent the fatality.

Heat

Many burn injuries are reported when IEDs explode in close proximity to soldiers. Accordingly, teachings of certain embodiments recognize that armor should incorporate mechanisms to mitigate heat-related injuries. However, teachings also recognize that not all soldiers and not all missions require heat-prevention armor, and such armor would add unwanted weight to the uniform. Accordingly, teachings of certain embodiments recognize the ability to configure armor based on intelligence information on threats in the area. In some embodiments, such heat-prevention armor would reduce the frequency of first, second, and/or third degree burns.

Blast Pressure

Although humans cannot see air, there are molecules all around, and they have weight. There are miles of air above in the atmosphere, and it is constantly weighing down on the earth's surface. However, humans are not aware of this weight because human bodies have gas inside that provides an equal and opposite force to the atmospheric force, in accordance with Isaac Newton's equal and opposite force law. Human bodies are made to live in this environment. This phenomenon is the driving force behind astronauts requiring spacesuits. In space, there is not a large amount of air weighing down, and thus the astronaut's body would not be able to cope. The air within the body would want to expand outwards and cause it to explode. A space suit provides the astronaut an environment that simulates the atmospheric forces experienced on earth.
This weight causes a force over a given area, or “pressure.” At sea level, air has a pressure of approximately 14.7 pounds per square inch (psi). Thus, in normal conditions, a surface area that is 1 inch by 1 inch will feel 14.7 pounds of force. Overpressure occurs when that surface feels anything more than 14.7 pounds, while underpressure exists when there is less than 14.7 pounds. For example, humans deep underwater experience overpressure because of the large amount of water weighing down. On the other hand, humans in space without a spacesuit experience underpressure because outer space exerts less force than on earth.
Pressure may be characterized by absolute pressure or gauge pressure. Absolute pressure is the actual force over a given area. When atmospheric pressure was referred to as 14.7 psi, this value was the absolute pressure. The gauge pressure is the difference of absolute pressure relative to the atmosphere. For example, if the gauge pressure is said to be 35.3 psi, the absolute pressure would be 50 psi (atmospheric pressure+gauge pressure=14.7 psi+35.3 psi=50 psi). Whenever people refer to a pressure reading, they are almost always referring to the gauge pressure. The remainder of this disclosure will refer to pressure values according to gauge pressure readings because gauge pressure easily distinguishes between normal pressure, overpressure, and underpressure: any negative value is underpressure, a zero value is normal atmospheric pressure, and any positive value is overpressure.
In order to understand how an explosion causes pressure changes, it is important to understand what factors influence pressure. These effects can be seen in the ideal gas law:
P·V=n·R·T (1)
wherein P is pressure, V is volume, n is the amount of gas, R is a constant, and T is temperature.
The ideal gas law illustrates how pressure relates to volume, temperature, and the amount of gas. These relationships are illustrated in FIG. 1. For example, without changing the temperature, compressing a given amount of gas (decreasing the volume) will force the pressure to increase. From the equation, one can see that P·V=Constant (when n and T do not change). Thus, if the volume lowers, the pressure must rise.
Similarly, temperature can also be related pressure. At hotter temperatures, a gas wants to expand. This causes the gas to push harder against the objects around it. Thus, if a given sample of gas is heated and not allowed to expand, it will have a higher pressure. From the equation, you can see that P/T=Constant (when n and V do not change). If temperature rises, pressure must also rise.
Lastly, if the quantity of air changes, it will effect the pressure. If more gas is added, it is similar to compressing the volume. If the volume and temperature are not changed, and more gas is added, the pressure will increase. From the equation, one can see that P/n=Constant (when V and T do not change).
Underpressure as well as overpressure can have independent, yet serious impacts on the human body. Humans experience underpressure when on an airplane during takeoff. The gas inside the human's ear is at a higher pressure than the air around the human. In order to equalize the pressures, the gas inside the human's ear escapes and causes the ears to “pop.” Likewise, when a plane lands, a human will feel the impact of overpressure: the gas inside the human's ear is now at a much lower pressure than the surrounding environment, and air rushes in.
Now imagine that, instead of takeoff lasting a minute, the entire takeoff happens in a fraction of a second. The air rushing out of the human's ear will be so dramatic that it will cause the eardrum to rupture. Likewise, the blood vessels in the human's brain and lungs will explode outwards causing concussions and potentially even death. The fluid in the human's eyes could even burst outwards, causing blindness. Now imagine that the plane quickly lands in a fraction of a second. Similar effects happen with the overpressure. Instead of gas and fluid exploding outwards, they will now be crushed. For example, the blood vessels in the lungs will collapse, restricting the body's flow of oxygen.
Any exposed fluid/gas organ will be susceptible to damage. Three of the primary pressure injuries occur at the ears, eyes, and lungs. Both underpressure and overpressure have similar primary injuries that include ear drum ruptures, lung damage, and blindness. These may lead to additional injuries, such as loss of consciousness, central nervous system damage, and death.
Blast waves for virtually all military munitions contain both overpressure and underpressure regions which can both inflict massive amounts of harm to a human. In some cases, the combination of both overpressure and underpressure may be worse than one or the other individually. When an explosive goes off, it imparts a large amount of energy into compressing the air in the immediate vicinity. This compression forms the basis for the first part of a blast wave, the shock wave. The compression of the air puts it in an overpressure state (see FIG. 1). Human ear drums begin to rupture at 5 psi. Above 50 psi, other organs, particularly the lungs, become severely damaged. Often times, shock waves from explosions can be well above 100 psi, resulting in immediate death.
However, the compressed air of the shock wave did not materialize from nothing. It came from the region following the shock wave. This region is now lacking that air resulting in underpressure.
FIG. 2 illustrates the overpressure and underpressure regions of the blast wave as a function of time. FIG. 2 displays the data obtained by a sensor that was placed nearby an explosion. Initially a shock wave hits the sensor causing the extremely high pressure spike. This pressure then quickly decays and a region of very low pressure, the underpressure, follows it. All of this occurs over an extremely small time frame. The scale on FIG. 2 is in microseconds, μs (1,000,000 microseconds=1 second).

Electromagnetic (E&M) Energy

Detonation of explosive material encased in metallic structures can cause an induced E&M field of sufficient strength to cause hazards to nearby personnel. E&M power flows within the near field zone is highly complex. Higher order field geometries can result in seemingly paradoxical effects such as circulation of the E&M Poynting vector around then back into the reactive near field. This implies that power amplitudes and hence field intensities are many times higher in the near field than in the far field. Additionally the near field reactive zone allows for the excitation of localized, bound, or local environment surface (such as ground surface) guided fields that have large longitudinal components for the electric field and complex power propagation. These localized bound surface waves generally do not propagate to the far field hence making their detection and measurement problematic but the threat to personnel no less real.
Longitudinal oriented electric fields and other non-traditional electromagnetic field configurations are induced in the near field or an even more complex region within the near field known as the extreme reactive near field zone. In the far-field region the electric and magnetic components that constitute the E&M wave are essentially at right angles to the flow of power. This condition of power flowing oriented parallel to a time varying electric field changes the coupling characteristic of the wave and could easily penetrate metallic enclosures (such as armored vehicles). Such reactive/extreme near field complex E&M field patterns and higher order patterns are almost always neglected in E&M engineering and analysis to reduce the complexity of that analysis. However, the end result can be significantly higher electric field values in the near field resulting in higher levels of ionizing radiation, which is very dangerous to living tissue according to many known reports in open medical literature.
Albert Einstein noted that for accurate descriptions of electromagnetic field structure and the interactions with materials at least the first five terms in the expansion are needed to accurately account for power flow and interactions with matter (rather it be metallic shielding or human nerves). The implications are that the higher order Einstein and Sommerfeld type electromagnetism is required to accurately describe the power flow, absorption and material effects. The common perturbation theory approach will give incorrect predictions in the E&M field inducing near field conditions, all of which may apply during an IED detonation.
Gabriel Kron's subsequent applications of those most sophisticated electromagnetic theories to practical electrical engineering have the only completely physical accurate description of anomalous effects in rotating electrical machines requiring the presence of far more complex geometric structures in the E&M field than is assumed in simple electrodynamics. Such complex field structures could very well be intense with a high explosive event as many IEDs are known to be. It should be noted that high explosives are those with supersonic shock fronts. Low explosives are those with subsonic shock fronts.

Radio-Frequency (RF) Effects on Biological Tissue

In nearly all regimes of the RF spectrum, any work that has been done has found biological effects, most often pathological neurological effects created by a variety of mechanisms in the human nervous system under the presence of E&M fields. Effects can include induction of dangerous EMF's and voltage transients in sensitive nerves, such as low frequency VLF or ELF driven transport of calcium and other ions across the blood brain barrier. This type of damage is potentially permanent, as the cell structure can be damaged either by large field transients or pathologic ion transport of electrochemical effects created by such strong fields.
Unfortunately, bio-effects data related to the higher order electrodynamics terms as reported by Einstein, Kron, and others, is not available. The most rigorous research available is small portions of vast amounts of RF weapons related work performed in the former Soviet Union. These data are of particular concern as it revealed a variety of E&M induced nerve trauma that has not been studied in the USA. For example, Soviet research revealed that nerve trauma could and will arise from the following areas:

- Fields intense enough to induce heating effects
- Dielectric breakdown along nerve pathways but at much lower amplitudes than expected (20 dB breakdown level).
- Trauma that manifested as either permanent or very long recovery period nerve injury known as “nerve crimping.”
  Tests in the former Soviet Union verified that animal nerves would undergo a literal crimping or bending and folding. This was sufficient to induce effects from paralysis in severe cases to lack of coordination in less severe cases. Also associated with such exposure were noted apparent severe physical fatigue in the test animals, indicating that nerve trauma has created an overall reduction in body somatic function and immune system function.

Electromagnetic Radiation

Electromagnetic radiation is a self-propagating wave in space—the phenomenon sensed by the human eye as light (provided the radiation is in the correct wavelength range as discussed below). E&M radiation comprises an electric and magnetic field, which oscillate perpendicular to each other with the two fields in phase, and they travel in the direction of energy propagation. E&M radiation is typically classified into types according to the frequency of the wave. These various types are generally divided into and referred to as: radio waves, microwaves, terahertz radiation, infrared radiation, visible light, ultraviolet radiation, X-rays, and gamma rays. These categories are listed in decreasing wavelength (or increasing frequency); radio waves have the longest wavelengths, and Gamma rays have the shortest.
E&M fields are known to comply with the properties of superposition, so fields due to particular particles or time-varying electric fields contribute to the fields due to other causes. These fields are also (simultaneously) vector fields and all of the field values will obey the laws of vector addition. These properties will collectively cause various phenomena including refraction and diffraction (known behavior of all E&M radiation, including light).
Interestingly, a traveling E&M wave, which is incident upon an atom if it is of proper wavelength and energy that wave, will cause an oscillation in the atoms. This will cause these atoms to emit their own E&M waves. These emissions have been shown to (through vector addition) to cause changes in the incident wave.
E&M radiation (of all forms) oscillate. This radiation is not affected by traveling through static, electric, or magnetic fields in a linear medium (vacuum is a prime example of a linear medium). In nonlinear media (cages of wire, crystal structures, etc) interactions can occur between the incident radiation and static, electric, and magnetic fields. These interactions include such widely researched affects such as the Faraday effect (as in Faraday Cage) and the Kerr effect.
When considering the phenomena of refraction, a wave will cross from one medium to another. The different densities alter the speed and direction of the radiation upon entering the new medium. Snell's law can determine the degree to which this refraction takes place. One example of refraction to which everyone is familiar is light passing through a prism. Teachings of certain embodiments recognize that refraction principles may be used to divert harmful E&M energy away from a human being. For example, some embodiments recognize that a refractive material may be placed on a soldier's shooting glasses or other equipment as a coating. This coating may cause some of the energy from the electromagnetic wave incident on the soldier away from the soldier's eyes, prohibiting the E&M waves from entering the brain from behind the eyes. Similarly, an absorptive layer can be added to the soldier's equipment.
The scientific principles of E&M radiation are known as electrodynamics, which is a subfield of electromagnetism. E&M radiation is known to exhibit both wave and particle properties. This is commonly referred to as wave-particle duality. The wave characteristics are more apparent when E&M radiation is measured over larger timescales or large distances. The particle characteristics are much easier to see when measuring small distances and very small timescales. Both of these characteristics are not in doubt by the scientific community, having been predicted theoretically and confirmed in a large number of experiments.
An important characteristic to understand about any E&M wave is frequency. The frequency of any wave is merely the rate at which it oscillates. Frequency may be measured in hertz, which may be equal to one oscillation per second.
If one wave were to be analyzed in isolation, one would see successive troughs and crests. The distance between two adjacent crests or troughs is called the wavelength. Waves in the E&M spectrum vary in length from very long radio waves to very short gamma rays. The frequency of a wave is inversely proportional to the wavelength and can be determined by the following equation:
v=fλ (2)
wherein v is the speed of the wave (e.g., v=c, which is the speed of light in vacuum, which is less in other medium), f is the frequency, and λ is the wavelength.
As waves cross the boundary between one medium and another their speeds change but their frequencies remain constant.
Interference is the superposition of two or more waves resulting in a new wave pattern. If the fields have components in the same direction, they constructively interfere; by the same mechanism, opposite direction components cause destructive interference.
Energy in any E&M wave is referred to as quantized. In the particle examination of radiation a wave comprises discrete packets of energy or quanta called photons. The frequency of the wave is proportional to the magnitude of the particle's energy. Moreover because photons are emitted and absorbed by charged particles they act as transporters of energy. The energy per photon can be calculated from what is known as the Planck equation:
E=hf (3)
wherein E is energy, h is Planck's constant, and f is frequency. This relationship of photon-energy is a particular case of the energy levels of the more general electromagnetic oscillator whose average energy, which is used to obtain Planck's radiation law. This can be shown to differ sharply from that predicted by the equipartition because of the quantum effects at low temperature.
When a photon of sufficient energy is incident upon and absorbed by an atom, it excites an electron raising it to a higher energy level. If the energy is high enough when the electron jumps to a high enough energy level, it will be released from the atom. This entire process is referred to as photoionisation. An electron when it descends to a lower energy level of electrons in atoms are discrete, each elements emits and absorbs its own characteristic frequencies.
Any electric charge, which accelerates, or a changing magnetic field (such as charged metals coming out of an IED) produces electromagnetic radiation. Electromagnetic information about the charge travels at the speed of light. When any wire (or other conducting object such as an antenna) conducts alternating current, electromagnetic radiation is propagated at the same frequency as the electric current.
In general, E&M radiation collectively is referred to as the E&M spectrum. This spectrum is divided by wavelength into electric energy, radio, microwave, infrared, visible light, x-rays and gamma rays. The behavior of this radiation depends on its wavelength. Higher frequencies have shorter wavelengths and lower frequencies have longer wavelengths. When considering E&M radiation interacts with single atoms and molecules its behavior depends on the amount of energy per quantum carried.

Electromagnetic Near-Field Radiation

Inside of electromagnetic radiation are two different types of fields. One is far field radiation, which behaves as discussed above. The other is near field radiation. Near field radiation is generally considered to be radiation in the physical area that is one-half wavelength or less from the radiative source. In other words, for radiation featuring a wavelength of ten meters, the near field would be the first 5 meters from the source.
Inside the electromagnetic near field, the electric and magnetic portions of the wave are not yet coupled. In this region the electric field values will be much higher than in the far field. This will cause this type of radiation to have more ionization potential than in the far field, which can be very dangerous for any living tissue, including soldiers situated in this region.

Electromagnetic Radiation and the Impact on Health

E&M radiation can be classified into ionizing and non-ionizing radiation. Which subcategory it falls into is dependent on if it is capable of ionizing atoms and breaking chemical bonds. Ultra-violet and higher frequencies are ionizing. These, in addition to electromagnetic energy in the near field condition, are especially dangerous for humans because neurons in the brain are negatively charged. If these neurons are in their positive or neutrally charged state, they are much more easily damaged. For example, in the case of a soldier within close proximity to an IED, ionizing waves may push the neurons into a positive or neutrally charged state right before the soldier is hit with a high pressure wave from the IED, which may cause extensive damage to the already-weakened positive or neutral neurons.
Non-ionizing radiation is also known to come from IED events and is known to be associated with two major potential hazards, electrical and biological. Additionally, in a military environment, induced electric current caused by non-ionizing radiation can generate sparks and create a fire or explosive hazard. Given how much a typical military vehicle carries in the form of munitions, this can be especially dangerous.
The changing electric and magnetic fields will induce an electric current in any conductor through which it passes. Strong radiation can induce current capable of delivering an electric shock. It can also overload and destroy electrical equipment.
Very high power E&M radiation can cause electric currents strong enough to create sparks when an induced voltage exceeds the breakdown voltage of the surrounding medium. In most cases this surrounding medium is air. These sparks can then ignite any flammable material or gases, which in some cases may lead to an explosion. This can be a particular hazard in the vicinity of military grade explosives.
One of the well understood biological effect of E&M fields is to cause dielectric heating. For example, touching an antenna while a transmitter is in operation has been known to cause severe burns in some cases. The overall heating effect varies with the frequency and power level of the E&M energy. The eyes are particularly vulnerable to RF energy in the microwave range. Each frequency in the spectrum is absorbed by living tissue at a different rate, called the specific absorption rate (usually shortened to SAR). This rate is typically written in units of watts per kilogram (W/kg). The IEEE and many national governments have published safety limits for exposure to various frequencies of electromagnetic energy based on SAR.
In addition, complex biological effects of weaker, non-thermal E&M fields may exist. This may include weak EMP fields, as well as modulated RF and microwave fields.

RF Shielding Material

The relative static permittivity (or static relative permittivity) of a material under some set of conditions is a measure of the extent to which that material concentrates electrostatic flux. The number is obtained from the ratio of the amount of stored electrical energy when a potential is applied, relative to the permittivity of a vacuum.
The relative static permittivity is represented mathematically as ε_rand is defined as
ε_r=ε_s/ε₀ (4)
wherein ε_sis the static permittivity of the material, and ε₀is the dielectric constant.
The relative static permittivity can be measured for static electric fields as follows: first the capacitance of a test capacitor C₀is measured with vacuum between its plates. Then, using the same capacitor and distance between its plates, the capacitance C_xwith dielectric between the plates is measured. The relative dielectric constant can be calculated from these measurements by
Relative static permittivity=C₀/C_x (5)
Time variant electromagnetic fields of this quantity are always frequency dependant and, in general, called relative permittivity.
The dielectric constant is a piece of information when designing capacitors and in other circumstances where a material might be expected to introduce some capacitance into a circuit. In the case of a material with a high dielectric constant is placed in an electric field, the magnitude of that field will be measurably reduced within the volume of the dielectric.
Dielectrics are used in RF transmission lines as well. For instance, in a coaxial cable, polyethylene can be used between the center conductor and outside shield. It can also be placed in waveguide systems to act as a shield. Optical fibers are examples of dielectric waveguides. They comprise dielectric materials that are purposely doped with some kind of impurity to artificially alter the relative permittivity to some desired value.

Use of RF Absorbing Materials for Prevention of Injuries

Teachings of certain embodiments that, because the brain is encased inside the skull, there are many ways in which RF absorbing materials may be useful in preventing RF pulses from having an impact on or adding to the level of TBI in a human.
The brain itself has neurons, and these neurons once damaged do not regenerate, as other types of human tissue will do. For example, broken bones will heal, broken neurons will not. These neurons in their natural state are negatively charged. Once neurons are neutral or positively charged they are easier to damage by being placed under pressure. As explained above, the RF pulse comes out of an IED at the time of explosion, but due to its velocity being equal to the speed of light, will reach the soldier's brain first, which could remove some electrons from these neurons and leave them neutral or positive; then some number of milliseconds later, a very large pressure wave hits the soldier. These two things combined could serve to cause a larger level of TBI than either one could do.
Accordingly, teachings of certain embodiments recognize the ability to shield the head from these injuries using RF absorbing materials, such as a dielectric material.
In some embodiments, the weakpoints on the head may be the most heavily protected or even the only areas protected. These weakpoints may include the eyes and the ears. Teachings of certain embodiments recognize that protecting those points may give the largest impact to the number of soldiers wounded. After these points, the entire head may be shielded using the proper dielectric material.
Embodiments recognize that stopping the RF will not stop these injuries and the pressure wave will still cause damage; however, embodiments also recognize that the number and severity of these types of injuries will be greatly reduced. In other words, some embodiments may include the capability to reduce the severity of potential injuries from being traumatic to being something closer to mild concussions in many cases.
Teachings of certain embodiments recognize that protective materials may be incorporated into any suitable armor (ballistic, blast, etc.). Examples follow.
FIG. 3 shows a protection system 100 according to one embodiment. The protection system 100 features a human wearer 105 wearing a helmet 110, a chinstrap 120, and a visor 130. In some embodiments, the helmet 110 may feature an absorbing layer configured to absorb an RF electromagnetic pulse. For example, in some embodiments, the helmet 110 may be configured to absorb an electromagnetic pulse that has a frequency of less than twenty gigahertz. Embodiments of the absorbing layer may include any suitable material, such as a dielectric material. Some embodiments of the absorbing layer may comprise carbon allotropes or other known non-toxic dielectric material.
In some embodiments, the helmet 110 may be configured to cover the ears of the human wearer 105. In some embodiments, the helmet 110 may feature the visor 130, which may be configured to shield the eyes of the human wearer 105. In some embodiments, the visor 130 may feature a coating configured to reflect, refract, or absorb energy from an RF electromagnetic pulse and away from the eyes of the human wearer 105. In some embodiments, the coating may be configured to reflect, refract, or absorb microwave electromagnetic energy away from the eyes of the human wearer 105.
FIG. 4 shows a pair of protective goggles 140 according to one embodiment. In some embodiments, the goggles 140 may be configured to be worn with the helmet 110 of FIG. 3 and cover the eyes of the human wearer 105. In some embodiments, the goggle lenses may feature a coating configured to reflect, refract, or absorb energy from an RF electromagnetic pulse away from the eyes of the human wearer 105. In some embodiments, the coating may be configured to reflect, refract, or absorb microwave electromagnetic energy away from the eyes of the human wearer 105. In some embodiments, the goggles are transparent or translucent in at least the 400-700 nanometer wavelength range (known as the visible light spectrum).
FIG. 5 shows a face mask 150 according to one embodiment. In some embodiments, the face mask 150 may be configured to couple to the helmet 110 of FIG. 3 and cover the jaw of the human wearer 105. In some embodiments, the face mask 150 may feature an absorbing layer configured to absorb an RF electromagnetic pulse.
FIG. 6 shows an example protection system 200 according to another embodiment. The protection system 200 features the human wearer 105 of FIG. 3 wearing the helmet 110, the goggles 140, and the face mask 150 of FIGS. 3-5. In this embodiment, the human wearer 105 is also aiming a weapon 160 while wearing protective items 110, 140, and 150.
Modifications, additions, or omissions may be made to the systems and apparatuses described herein without departing from the scope of the invention. The components of the systems and apparatuses may be integrated or separated. Moreover, the operations of the systems and apparatuses may be performed by more, fewer, or other components. The methods may include more, fewer, or other steps. Additionally, steps may be performed in any suitable order. Additionally, operations of the systems and apparatuses may be performed using any suitable logic. As used in this document, “each” refers to each member of a set or each member of a subset of a set.
Although several embodiments have been illustrated and described in detail, it will be recognized that substitutions and alterations are possible without departing from the spirit and scope of the present invention, as defined by the appended claims.
To aid the Patent Office, and any readers of any patent issued on this application in interpreting the claims appended hereto, applicants wish to note that they do not intend any of the appended claims to invoke paragraph 6 of 35 U.S.C. §112 as it exists on the date of filing hereof unless the words “means for” or “step for” are explicitly used in the particular claim.

Claims

1. A system for protection against traumatic brain injury, comprising:

a helmet adapted to be worn on the head of a human wearer;

a layer of dielectric material adjacent the helmet, the layer of dielectric material configured to absorb at least a portion of a radio-frequency (RF) electromagnetic pulse with a frequency of less than twenty gigahertz originating from an Improvised Explosive Device (IED) detonation, wherein the absorbing layer is configured to cover the ears of the human wearer;

a visor coupled to the helmet and configured to shield the eyes of the human wearer;

a coating adjacent to the visor, the coating configured to:

reflect, refract, or absorb energy from the RF electromagnetic pulse away from the eyes of the human wearer, and

reflect, refract, or absorb microwave electromagnetic energy away from the eyes of the human wearer;

a face mask coupled to the helmet and configured to cover the jaw of the human wearer; and

a second absorbing layer adjacent the face mask, the absorbing layer configured to absorb the RF electromagnetic pulse.

2. A system for protection against traumatic brain injury, comprising:

a helmet adapted to be worn on the head of a human wearer; and

an absorbing layer adjacent the helmet, the absorbing layer configured to absorb at least a portion of a radio-frequency (RF) electromagnetic pulse.

3. The helmet system of claim 2, wherein the RF electromagnetic pulse has a frequency of less than twenty gigahertz.

4. The helmet system of claim 2, the absorbing layer comprising a dielectric material.

5. The helmet system of claim 2, the absorbing layer comprising carbon allotropes.

6. The helmet system of claim 2, the absorbing layer configured to absorb at least a portion of a RF electromagnetic pulse originating from an explosive event.

7. The helmet system of claim 6, wherein the explosive event is an Improvised Explosive Device (IED) detonation.

8. The helmet system of claim 2, wherein the RF electromagnetic pulse is a near-field RF electromagnetic pulse.

9. The helmet system of claim 2, wherein the absorbing layer is configured to cover the ears of the human wearer.

10. The helmet system of claim 2, further comprising:

a visor coupled to the helmet and configured to shield the eyes of the human wearer; and

a coating adjacent to the visor, the coating configured to reflect, refract, or absorb energy from the RF electromagnetic pulse away from the eyes of the human wearer.

11. The helmet system of claim 2, further comprising:

a coating adjacent to the visor, the coating configured to reflect, refract, or absorb microwave electromagnetic energy away from the eyes of the human wearer.

12. The helmet system of claim 2, further comprising:

a second absorbing layer adjacent the face mask, the absorbing layer configured to absorb at least a portion of the RF electromagnetic pulse.

13. The helmet system of claim 2, further comprising a goggle apparatus, the goggle apparatus comprising:

a goggle frame, the goggle frame adapted to be worn by the human wearer with the helmet;

one or more goggle lenses coupled to the goggle frame, the one or more goggle lenses configured to cover the eyes of the human wearer; and

a coating adjacent to the one or more goggle lenses, the coating configured to reflect, refract, or absorb energy from the RF electromagnetic pulse away from the eyes of the human wearer.

14. The helmet system of claim 2, further comprising a goggle apparatus, the goggle apparatus comprising:

a coating adjacent to the one or more goggle lenses, the coating configured to reflect, refract, or absorb microwave electromagnetic energy away from the eyes of the human wearer.

15. A system for protection against traumatic brain injury, comprising:

a goggle frame, the goggle frame adapted to be worn by a human wearer;

a coating adjacent to the one or more goggle lenses, the coating configured to reflect, refract, or absorb energy from a radio-frequency (RF) electromagnetic pulse away from the eyes of the human wearer.

16. The system of claim 15, the coating further configured to reflect, refract, or absorb microwave electromagnetic energy away from the eyes of the human wearer.