Tag: humans

Invisalign: A Perfect Alternative to Traditional Dental Braces?

Did you ever have dental braces as a child, or perhaps later in life?

If so, then you were experiencing biomechanical forces in motion within the confines of your own mouth! The mechanical basis of dental braces is actually quite simple: brackets and wires apply forces and moments to your teeth in order to push, pull, or rotate them into their proper positions. Since 1998, the “Invisalign” technology has offered the aesthetically pleasing alternative of clear (invisible) retainer trays in order to satisfy a growing societal distaste for the visual appearance of traditional braces. Perhaps those who remember the social anxiety that came with having braces (especially at a younger age) might be jealous of this new alternative! But is this technology just as effective as traditional treatment?

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Wreckage Before the Real Crash: The Biomechanics of Crash Test Dummies

Every 25 seconds, someone is killed in a car accident, resulting in more than 1.25 million deaths worldwide each year.

Two fully assembled crash test dummies seated in car awaiting testing
Photo by Wikimedia Commons, Dynamic Test Center

As a result, dummies are an important tool used in many safety tests for car crashes, and they help to inform many design decisions for automobile manufacturers. Since these dummies are used to assess human behavior in many types of situations involving collisions, swerving, and other performance measures, the primary goal for dummy creators is to imitate human response as closely as possible using artificial means.

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Therefore, biomechanics plays an integral role in dummy design, from choosing materials that accurately reflect limb stiffness, to assembling ball-and-socket joints that sever when undergoing a certain threshold stress or strain. There are many techniques that researchers use – from computational models to in-field testing – to ensure these dummies reflect the parameters and properly inform the design decisions they are a part of.

Cross section diagram of dummy illustrating the assembly of different body parts
Photo by National Highway Traffic Safety Administration

      Manufacturers routinely spend millions of dollars each year to develop and fine-tune the dummies (or more technically known as anthropomorphic test devices or ATDs) that they implement in their testing procedures. Its history can be traced all the way back to 1949, where the US Air force implemented a dummy for test ejection seats, while they were first implemented commercially by General Motors more than 30 years later. They have undergone many advancements in terms of their accuracy and manufacturing efficiency, arriving at the now ubiquitous Hybrid-III model, which resembles a 50th percentile adult “family man” male that is used in almost all testing simulations. Although many cadever models have been explored, these artificial models offer the most consistent and reliable solution to testing needs, which involves blunt head-on crashes, various types of rollovers, and other rear-based and side-based collisions. By equipping dummies with different kinds of sensors, primarily consisting of MEMs accelerometers and other force transducers, dummies provide predictive power on the impact of different simulation parameters on driver safety and other outcomes.

Demonstration of the head drop test set-up described in the main text body
Photo by National Geographic on Youtube

            Dummy performance analysis can be found both in creation of the dummies, ensuring the dummies have the correct human mechanical properties, and in dummy testing, anticipating damages in crashes. Both see a heavy cross-section in biology and mechanics, best illustrated by the head-drop test in the initial development stage. Here, a dummy head undergoes a drop from a predetermined height, and sensing systems ensure the model has optimal weight and damping properties in comparison to in vivo concussion testing. This way, when the commonly used QMA Series 3 DoF Force Transducer later measures neck whiplash force (the most common cause of car crash injury), testing models can be confident such data will reflect real-world collisions. These kinds of before and after tests are used in all parts of the dummy, from parts as large as the lower back, to parts as small as the hinge joint in a finger knuckle. Such precision is needed in all areas to increase the predictive power of dummies, since details like Young’s Modulus (a measure of stiffness) in the chest area affects steering wheel impact displacement, while the coating paint consistency affects the skin abrasions associated with friction and rubbing. Each part of the dummy is crafted meticulously, and as such, the manufacturing and design process of the dummies involves a fast knowledge of physics, biology, and everything in between. Some additional overviews and readings can be found here and here.

How Lower Body Mechanics Unlock Performance in the Pitching Delivery

Why can some pitchers throw 105 mph and some only 85? Baseball players are continuously trying to throw the ball faster and hit the ball further. The lower body muscles, especially the gluteus maximus/medius, adductors and and other pelvic movers, are essentially what power the throw and what can directly increase pitch velocity. Learning how to efficiently use the muscles in the lower body while pitching will allow players to optimize their performance, train correctly off the field, and prevent injuries.

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Pacific Rim In Real Life?

How Close are we to a Pacific Rim Reality?

A picture of a kaiju infected robot
A photo from the movie Pacific Rim 2

Remember those giant hybrid kaiju-fighting robots from Pacific Rim where the brain of a kaiju (strange beast in Japanese) has successfully infected the mechanical brain of the robots and turned human’s greatest defense against them ? Well, it turns out, the boundary between science fiction and reality isn’t as far as we thought. A researched field “Necrobotics” has taken the world by storm and it is so new that Google is still highlighting “Necrobotics” as red. Imagine a world where nature’s most complex design is integrated into human’s innovation, leading to the most incredible biohybrid systems. If you are drawn the future application of this field or the potential harmony between biology and robotics, you’re in for a treat. In this blog post, we’ll be exploring the existing researches within Necrobotics and the future outlook on this unique field.

Necrobotics, a term derived from “Latinized form of Greek nekros” (relating to death ) and “robotics,” may sound a tad bit eerie, but it’s far from sinister. In fact, it’s all about bringing life to machines. The heart of the research is focused on producing biohybrid system that utilizes the intricate abilities of a living organism while combining with the precision and flawless decision making skills of a robot. Similar to our natural world, it draws inspiration from our environment such as the symbiotic relationship of Bees feeding on a flower’s nectar while carrying its pollen from plant to plant.

So, why should you be interested in this intersection of biology and technology? The applications are nothing short of astounding. One day, we will have biohybrid robots aiding in disaster relief events, enhancing our healthcare capabilities and assisting us in answering humankind most complex questions. These robots are able to mimic natural organism abilities, making them more adaptable, versatile, and resilient than conventional robots. From robotic limbs that respond to neural signals in the body to machines that slither like snakes, Necrobotics are in prime position to push humankind to the next level.

Gecko skin adhering to smooth surfaces
Photos from the article “Evidence for van der Waals adhesion in gecko setae”

Scientists and engineers have developed a variety of technology by studying organisms that have evolved over millennia of evolution. These technology include surface wettability modification based on lotus leaves and Namib beetles, adhesion mechanisms that mimic gecko toes, and even sensing for smart materials by imitating the color-changing chameleon and the humidity-sensitive pine cone. In order to inform the design of robots and actuators, researchers have also taken inspiration from the locomotion of aquatic and terrestrial animals, such as starfish, jellyfish, and cephalopod. Here is a famous example of dead spider corpse used as a mechanical claw.

In conclusion, these scientific topics may have been initially perceived as science fiction but it has quickly garnered attention and are becoming a crucial step for mankind to take. Future discoveries in this field will have the potential to redefine countless industries while acknowledge nature’s design. So if you’ve ever imagined a time where science and nature coexist, now is the perfect time to get excited about necroboticsᅳthe future is here, and it’s amazing.

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You’re En Pointe! Biomechanics and Ankle Injury Risk in Ballet Dancers

Dancing in pointe shoes raises the risk of injury for female ballerinas. Complex balletic movements require elevated muscular efforts and can put excessive stress loads on the ankle bones. Not many biomechanical studies focus on ballet, even as findings could contribute to decreased injury risk for dancers. A number of factors, such as ground reaction forces, ankle sway, and shoe flexibility can affect a dancer’s injury risk. But which factors contribute most? 

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Strengthening the Spine with Pedicle Screws

How are pedicle screws being used to strengthen the vertebrae in spinal fusion surgeries?

Xray of human spine with misaligned vertabrae. Then shows same spine that is aligned using pedicle screws.
Image from Seattle Neuro. Pedicle screws are inserted in the right image to align the unstable vertebrae originally shown left.

In the US alone, over 300,000 spinal fusion surgeries are performed every year to correct for fractures, deformations, or spinal instabilities. These surgeries are often performed by inserting a pedicle screw into the damaged vertebrae to increase the strength of the fusion. These screws are most often used in cases where the bone in the surrounding area is already weak, which decreases the likelihood of success in the surgery. Essentially, pedicle screws are used in damaged bones to increase their strength, in turn increasing the likelihood of success in a high-risk patient.

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Pressed and stressed: How understanding tumor biomechanics may be the future for treating patients with triple-negative breast cancer

Despite unstinting interventions such as chemotherapy and surgical tumor removal, approximately 40% of patients with stage I-III triple-negative breast cancer (TNBC) will experience tumor recurrence. Fortunately, not all hope is lost. The advent of immune checkpoint blockade (ICB) immunotherapy—a type of therapy that uses one’s own immune cells to kill the cancer—has shown great promise for the treatment of TNBC. However, as Dr. Azra Raza says in her book, The First Cell: And the Human Costs of Pursuing Cancer to the Last, these “immune approaches are not universally curative and, at present, help very few patients.”

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Sensing tension in the brain tumor microenvironment

According to Azra Raza, a Professor of Medicine at Columbia University in New York, high-grade brain cancer called glioblastoma is “one of the most aggressive, ruthless killers known to mankind”. Indeed, despite recent advances in cancer therapies, glioblastoma remains incurable with a median survival of 15 months which has not improved substantially in the last 20 years. This poor prognosis is, in part, due to the highly immunosuppressive microenvironment that allows tumors to evade anti-tumor immune response and promotes resistance to immunotherapy – a kind of therapy that uses your body’s own immune system to find and eliminate tumor cells.

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