How do helmets protect our fragile brains?

On July 6th, Beijing time, head injuries and concussions could have dire consequences and may even affect lifelong. Can we find a panacea for brain safety? The brain is our fragile and valuable asset, encased in the thick, boneshell shell of the skull. To a large extent, the skull protects the brain from all possible harms in our daily lives. Beneath this “armored shield”, there are also multiple layers of protective film and cerebrospinal fluid that provide a buffer to the brain.

How do helmets protect our fragile brains?

Helmets are everywhere in our daily lives, how do they protect our fragile brains?

However, it is not enough to have time to protect bones. A heavy blow to the head can cause the skull to break, damaging the brain inside. Heavy blows can also cause the soft organ to wiggle back and forth within the skull, and when the brain hits the hard skull, its soft tissue can easily be damaged.

How do helmets protect our fragile brains?

Our brains are fragile organs protected by hard skulls, but sometimes require extra protection.

Collisions on the playground, bicycle accidents, falls or slips on construction sites, and injuries on the battlefield all pose more threats to the brain than everyday behavior, so we need extra protection for the brain. Helmets are the most common form of protection. However, the helmet cannot just thicken the protective case, but must match the use scene while providing the best possible protection.

With the advent of advanced new materials and creative thinking, a new generation of protective helmets is making our fragile brains safer.

Bike Helmet

The main function of bicycle helmets is to prevent direct collisions between the head and the ground. We rarely need helmets, but when they are needed, they are likely to be life-saving straws. However, the debate over whether it is necessary to wear a helmet continues in cycling circles. Some studies have shown that drivers get closer to helmet-wearing cyclists when driving, while others have found that cyclists are more aware of safety when they wear helmets. After carefully studying the actual effects of helmets in the event of an accident, Donal McNally, a bioengineer at the University of Nottingham in the UK, came to the unquestionable conclusion.

How do helmets protect our fragile brains?

Busy road conditions can expose cyclists to a variety of hazards if they fall or collide with a vehicle

McNally said: “I’ve done quite a bit of experiments to simulate real-world cycling impacts and the results show that helmets have a very good protective effect, especially for children. “

Although most cycling helmets are light in weight, they work very well. The housing of the helmet is made of hard materials, such as carbon fiber or polycarbonate, that disperse the impact force. Helmets are often designed to be “eggshell” shapes that sink when impacted, absorbing energy like a car’s impact buffer. Inside the helmet is a layer of foaming polystyrene that permanently deforms and absorbs energy during impact, further reducing the impact on the wearer’s skull. Foaming polystyrene, commonly known as Paulilong, is a high-quality version of polystyrene – the ubiquitous disposable foam lunch box is made from polystyrene.

McNally has experienced first-hand the role of bicycle helmets. In 2010, he was seriously injured when he was hit by a car while riding his bike. Based on his findings, McNally believes his injuries would have been worse without a helmet. He showed students pictures of broken helmets in class. “That helmet saved my life,” McNally said.

In terms of the impact of the brain, the rotational motion caused by an angle impact is quite a special challenge, which causes the brain to rotate and distort it in a short period of time. This is devastating. This is also why knockdowns in boxing are more likely to come from side or lower attacks, as unlike straight punches, these angled punches cause the head to spin.

“In many cases, this is not a factor, but for certain types of impacts, such as when hit by the truck’s rear view mirror, the damage to rotational motion can be very serious,” McNally said. “

Many of the new helmets are now equipped with a “multi-directional collision protection system” that helps prevent damage caused by rotational motion. The helmet was originally developed and tested by Swedish neurosurgeons in 2000. When the helmet is hit, a layer of material between the helmet’s shell and the lining slides, causing the outside of the helmet to rotate about a centimeter, diverting some of the potential impact on the brain.

Another new helmet safety technology, called WaveCel, uses a honeycomb structure. In the event of an impact, several layers of material in the helmet liner move and bend independently, absorbing the rotational motion and the force of the impact. The developers of the technology conducted a set of tests that showed a 59 percent chance of rotating damage from a standard helmet, a Mips helmet reducing the likelihood of damage to 34 percent, and a WaveCel helmet at 1.2 percent. However, the makers of Mips helmets say the data are controversial. An independent review by Virginia Tech found that the mips helmet was designed to provide a slightly better protective effect.

However, while current bicycle helmets may be very effective in protecting the skull, the problem of facial injury has not been resolved. A 2019 study by the Hannover School of Medicine found that 14 percent of bike accidents involved facial injuries, and whether or not to wear a helmet had no effect. The authors suggest that future bike helmets should include some form of facial protection. Currently, some extreme off-road cyclists wear helmets with armor or masks, but as always, it’s not easy for the public to wear them on everyday rides.

Helmet

Yellow hard hats are everywhere on construction sites, and visiting politicians wear them for photos. The hard hat is designed to prevent impact son-in-fall objects, as well as collisions or scrapes of low beams and other construction site hazards. The hard hat is usually made of thermoplastic or polycarbonate and has a suspended top strap inside, keeping the head and cap case 30 mm in clearance, reducing the chance of impact passing to the skull.

However, on sweaty construction sites, these hard hats can get hot, making staff uncomfortable, and some people take off their helmets as a result. Adding vents also weakens the housing of the hard hat. So a team at the Wellor Institute of Technology in India hopes to solve this problem with some built-in air conditioners. They designed a hard hat that included a radiator made from a phase-changed material based on paraffin. At the same temperature as the body temperature, the heating material melts and absorbs heat, keeping the wearer cool for a few hours.

Another team at the university is working on alternative materials for shock absorption. Hard hats are usually made from polymeric resins reinforced with synthetic fibers such as kevlar fibers or carbon fibers, but researchers are working to replace them with natural fibers that are more readily available and produced more environmentally friendly. They found that jute fibers, commonly used in sacks, ropes and carpets, had great potential as an alternative to increasing the strength of the hard hat.

Cricket Helmet

Cricket poses an extraordinary threat to a person’s head. Cricket weighs about 160grams and its centre is a cork ball, the outermost layer wrapped in leather, and can hit speeds of up to 161km/h in a match. Being hit by such a ball can easily lead to a fractured skull or a broken jaw, and if the impact is not in the right place, it can lead to blindness. In the most severe cases, it can even result in death. All this means that helmets and masks are essential in cricket. Modern cricket helmets include a cage-like mask and a hard cap to protect the skull.

In 2013, the UK introduced a new standard for testing projectiles for protective masks. Now, cricket helmet manufacturers like Masuri will use air cannons to fire crickets at helmets to prove their performance. They also strengthened facial protection and found that deflecting the ball was more effective than stopping the ball’s impact entirely.

How do helmets protect our fragile brains?

Hitting a cricket speed of up to 160km/h in the head or face can cause fatal injuries

“The batsman moves naturally to avoid any impact on the ball,” said Sam Miller, Masuri’s chief executive. “

They installed a double-rod grille on the mask, just below the eyeliner, with one column slightly lower than the other. “The back post forces the ball up and into the solid part of the cap, keeping the ball away from the player’s face,” Miller said. This design provides a high level of protection without hindering sight and making it increasingly popular among international cricketers. However, while the reinforced plastic shell protects the skull, there is a need for additional protection, especially if the ball may fly from behind.

In 2014, Australian cricketer Phillip Hughes died two days later after being hit in the neck by an irregularly bouncing cricket while trying to hook his batting. His death prompted the cricket helmet to be fitted with neck protection to provide extra protection for areas such as the back of the brain. For example, the Stemguard developed by Masuri is an accessory clamped behind the helmet grille to protect the back of the head and neck. Stemguard is made of thermoplastic polyurethane honeycomb and also uses crushed foam to enhance impact cushioning.

For now, however, this neck protection is just an additional option. Australian cricketer Steve Smith was not wearing a neck shield when he was hit by a 148km/h pitch in the recent Ashes Cup (series match between England and Australia). This example highlights one of the biggest challenges of the various head protection technologies: they don’t work unless people are persuaded to wear them.

Perhaps the biggest reason why cricketers don’t want to wear helmets is the heat and humidity. Helmets are usually ventded to help cool down, but optimization is another scientific challenge. Some researchers have experimented with special “sweating dummies” to compare different designs. Today, researchers can embed temperature and humidity sensors in their helmets to get real-time maps of “hot spots” and “wet spots” during the race. Such research will eventually make helmets cooler and more acceptable to athletes even on the hottest days.

Solve the problem of wrestling

Participation in American football has declined in recent years, in part because studies have shown long-term brain damage to players. This status quo has also prompted researchers to work to develop better head protection equipment. Unlike bicycle helmets, football helmets tend to consist of hard shells and foam liners because they cannot be replaced after each collision.

“Most helmets do a good job of reducing power transfer. That’s why skull fractures are rare in football,” said Alan Aruda, a mechanical engineer at the University of Michigan. Energy dissipation is essential to reduce the impact on the brain. “

How do helmets protect our fragile brains?

There is growing debate about how to protect AFL players from concussions and long-term brain damage

Alan Aruda’s team is working on a new helmet design to solve the problem. “Our approach treats the entire helmet as a composite structure, including one or more viscous layers,” she said. “

Adhesive elastic materials are very special, although they are solid, but in some ways like liquids, can flow and dissipate energy. The new helmet will use a synthetic viscous elastic polymer specially developed to respond to impacts in rugby matches. “Our design reduces the force and impact that passes to the skull and brain, thereby mitigating the impact,” Aruda said.

Some companies are also looking at ways to improve traditional helmet designs. Vicis’s Zero1 helmet has a deformable thermoplastic shell that reacts much like hard rubber when hit and absorbs some of the impact energy. Inside the helmet is a spring-like “column element” that absorbs shocks from different directions. Like the Mips design for bicycle helmets, this helps reduce the rotational force.

Spin injury is a special risk in American football, but it can reduce the force of impact to the head by smoothing the helmet. A team at Simon Fraser University in Canada is testing stickers that can be applied to the outside of helmets. The sticker consists of several layers of film, and a single oblique impact causes the outer layer to slide freely, reducing the rotation effect by up to 74%. However, the sticker needs to be replaced after a severe impact.

Protection on the battlefield

In 2018, two police officers opened fire on a group of U.S. soldiers at Camp Maywande in eastern Afghanistan, killing an Army chief of staff. Another soldier wounded in the ambush may also have been killed that day.

Sergeant Steven McQueen was hit in the back of the head at close range by a machine gun in the back of a pickup truck, knocking him to the ground. Amazingly, a few seconds later he stood up again and resumed the fight. The bullet hit his McQueen’s helmet, which absorbed the impact and stopped the bullet. The soldier survived in large part because of the helmet on his head that was remarkably resilient. The helmet is known as the “Head Integrated Protection System”.

How do helmets protect our fragile brains?

Modern combat helmets are strong enough to withstand bullets.

Like soldiers on the battlefield, military helmets face a unique and ever-changing challenge, including small, dense and high-speed objects, especially shell fragments and bullets.

In the early 20th century, soldiers wore helmets. Later in the 1970s and 1980s, helmets were replaced by Kefra helmets, but ancient and modern Kefra materials have been replaced by polyethylene. It’s not low-density polyethylene on beverage bottles and sandwich packaging, it’s super-high molecular weight polyethylene. The material can even intercept large-calibre rifle bullets at close range.

“The UHMWP is currently the best material for helmets,” said Lt. Gen. Ginger Whitehead, product manager for U.S. Army Soldiers Protective Equipment. “

UHMWP is made up of molecules a hundred times larger than ordinary polyethylene, which can be woven into fibers that look and feel similar to nylon, but are bulletproof.

“What makes us military helmets for the U.S. is 3M,” said Vasilyos Brahos, senior manager of defense product development at 3M, which makes military helmets for the U.S. “

The term “toughness” here is a technical term that includes both the force required to stretch the material and the stretch distance of the material before it breaks. UHMWP is a good interceptor of bullets precisely because it has strong stretching properties and absorbs a lot of energy without breaking.

The U.S. Army will adopt an improved helmet next year as the next generation of combat helmets, and better protective materials are being developed. “UHMWP is still relatively young and not fully utilized,” Brahos said. “

However, even if the helmet blocks the bullet, the wearer may still suffer blunt bruising. Marta Boroma, an engineer at the University of Technology in Valencia, Spain, said: “It’s very similar to other blunt bruises, such as injuries from hammers. “It’s just that in the case of a shooting, blunt bruising is caused by an object that can reach a speed of several hundred meters per second.

When the helmet is hit by a bullet, it deforms and bends inwards. If the deformation is greater than the distance between the inner surface of the helmet and the head, the bullet passes through the helmet and hits the head, causing relatively severe trauma. If the helmet is stronger and less deformed, the risk of trauma may be reduced, but this increases the chance of a bullet passing through the helmet. “From our point of view, the importance of preventing helmets from being pierced by bullets far outweighs the risk of any blunt bruising,” Brahos said.

The risk of a partial blunt bruising is considered the best trade-off at the moment. Marta Boroma’s team is working to identify the danger and set standards, including advising helmets for larger heads not to reduce the thickness of the liners. They believe the size of the helmet should be increased according to the proportion of the wearer’s head. Other researchers are also developing better shock-absorbing materials to try to further reduce head injuries.