The pirates of prosthetics peg legs and hooks – lesson – teachengineering electricity off


Students are introduced to prosthetics—history, purpose and benefits, main components, main types, materials, control methods, modern examples—including modern materials used to make replacement body parts and the engineering design considerations to develop prostheses. They learn how engineers and medical doctors work together to improve the lives of people with amputations and the challenges faced when designing new prostheses with functional and cosmetic criteria and constraints. A PowerPoint® presentation and two electricity worksheets grade 6 worksheets are provided.

Human bodies are able to withstand great forces and destroy unwanted foreign bacteria. However, the body can only handle so much. Sometimes, the effects of car accidents, war, animal attacks and bacterial infections cause excessive trauma with the only means of saving a person’s life being amputation. Biomedical engineers and doctors work together to continually improve and creatively invent amazing prosthetic devices to enable people to complete daily life tasks efficiently and effectively.

In addition to working together to continually enhance the design of replacement body parts—which includes dentures, eyes, facial bones, hips, knee joints, arms and legs—biomedical engineers and medical doctors are creatively innovating radical new ideas online electricity bill payment for prostheses. For example, they are able to attach muscles to electrodes connect to the prostheses. The muscles send information to the prosthesis, such as contracting or relaxing, and the prosthesis performs the movements, making it seem as though it is a functioning and communicating part of the body. And, this is just the beginning of future prosthetic design—for example, tissue engineering may someday enable us to regenerate entire replacement limbs.

(slide 2) Whether due to car accidents, wars, animal attacks (shark!), birth defects or bacterial infection, sometimes body parts, including major limbs, are damaged, missing or amputated to save peoples’ lives. Classic images of prostheses include Captain Hook from Peter Pan and other pirates with peg legs. The history of replacement body parts, or prostheses, can be traced to the ancient Greeks, Romans and Egyptians; for example, 3000-year-old mummies have been found with prosthetic toes and fingers. Before the 1840s, most people did not survive the amputation process due to the side-effects of shock, infection and blood loss. The medicine and tools at the time were limited, and prosthetic supplies were scavenged from whatever was available. Starting in 1842, anesthesia was used during surgery gas oil ratio, which enabled more precise surgeries and resulted in better prosthetic fits. The great number of amputees from the two World Wars in the 20th century increased the demand for more and better prosthetic designs.

What design challenges do engineers face in creating prostheses? One consideration is the location of the amputation. Does the replacement device need to include a movable joint, such as a knee or elbow? Will the prosthesis be designed to improve appearance only (cosmetic), such as an eye or ear, or does it need to perform some of the lost functions of the original limb, such as vision and hearing? The location on the body determines the necessary functions of the prosthesis so as to enable the person to resume daily life activities. Another consideration is the strength of the prosthesis compared to its weight. The material needs to be strong enough to perform the necessary functions and hold body weight if necessary but light enough to be moved easily. Another consideration is the attachment. How will the prosthesis be attached to the body? How do we keep it from falling off? Another consideration is cost. What materials are available to use? How much do they cost? Is the cost reasonable so that patients can afford the prostheses? These considerations and requirements become what engineers call the design criteria and constraints.

(slide 4) If we examine a simple prosthetic limb, such as one for a leg, we can see it is composed of four basic parts: interface, components, foot and cover. The interface, or socket, is where the prosthetic device meets the remaining part of the limb. This part usually includes a suspension system that uses some kind of attachment method, one of three techniques: 1) a suction valve that forms a seal with the limb, 2) a locking pin, or 3) a belt and harness. Another basic part is the components or pylon, which are the internal working parts of the prosthesis. The third basic part is the foot, which is an attachment that simulates the lost limb and helps with walking la gastritis and balancing. Of course, for an arm prosthesis, this would be a hand. The fourth basic part is a cover, which is an outer covering to make it look more lifelike.

(slide 5) Let’s talk about the four main types of artificial limbs. Transradial is a type that replaces an arm below the elbow including the wrist, hand and fingers. The transhumeral type replaces an arm above the elbow including the elbow, wrist, hand and fingers. The transtibial type replaces a leg below the knee, including the ankle, foot and toes. The transfemural type replaces a leg above the knee, including the knee, ankle, foot and toes. The more joints that are included in a prosthesis, the more complicated the design must electricity transmission efficiency be in order to provide the complexity of movements and functions.

(slide 6) One huge prosthetic advancement is the evolution of modern materials, which can make artificial parts stronger, lighter and more realistic in appearance and use. Some of the materials that have improved the designs are advanced plastics, carbon fiber composites and electronic components for control. Microprocessor-controlled knee prostheses help people climb stairs (left) and run races (right).

Copyright © (left) 2009 U.S. Army via Wikimedia Commons; (right) 2009 Tim Hipps, U.S. Army via Wikimedia Commons

(slide 7) What are different categories or types of modern prostheses? If we examine some examples, we can see the advancement of materials and corresponding increase in possibilities for patients. In specialty prostheses, carbon fiber can be used to enable people to run like they were able to before amputations. The carbon fiber is light enough for the patient to move it quickly and easily, yet strong enough to hold more the than the weight of the person. It also gives the person a slight bounce, just like our feet do. In functional prostheses, electronic systems can be utilized to enable a person to pick up items and catch balls during sports.

(slide 9) The future of prostheses lies in the level of functional capabilities provided by the inventions and their electronic systems. In the 1950s, cable control systems were often used for people with transradial prostheses. Different body motions—such as a shrug or arm extension—caused the external cable to move, resulting in the hand moving as desired. Today, we use electrodes that are attached or implanted in the residual limb. These electrodes sense the muscles and are able to know how the hand should move as if it were attached. If the residual limb is from a transhumeral amputation, more muscles are needed for the electrodes to understand how the hand should move. Engineers are also working with medical doctors to implant electrodes electricity vampires in the brain to utilize neuron signals to control residual limb muscles. This approach has great potential to result in prostheses that enable people to have fully functional moving limbs again.

(slide 10) To accomplish their goals when designing prostheses, biomedical and mechanical engineers rely j gastroenterol on their thorough understanding of a variety of subjects including anatomy, neurology, biomechanics, and sensor motor control. Applying what they know about these subjects enables engineers to design prostheses and other medical devices that can improve body mobility and function for patients.

• A Zombie Got My Leg Challenge: Making Makeshift Legs – Students experience the engineering design process as they design and construct lower-leg prostheses in response to a hypothetical zombie apocalypse scenario. Working as engineers, they consider project criteria and constraints, use limited supplies and barter for additional materials. Teams test their finished prostheses and make five-minute class presentations.

Prostheses have evolved throughout the years from simple pieces of wood to complex designs using composite materials enabling amputees to run or snowboard with no disadvantages. The world is constantly adapting to the knowledge humans gain and the new materials designed. In the future, it is possible that entire new limbs may be regenerated or prostheses will be fully electronically integrated with the body’s neurons, giving amputees the use of limbs as if they were never lost.