prosthetics

prosthesis (from Ancient Greek prósthesis, “addition, application, attachment”) is an artificial device that replaces a missing body part lost through trauma, disease, or congenital conditions.

• history of prosthetics from peg legs to the FlexFoot

Implant – a medical device manufactured to replace a missing biological structure, support a damaged biological structure, or enhance an existing biological structure. Medical implants are man-made devices. Material such as titanium, silicone or apatite are used depending on what is the most functional. In some cases implants contain electronics e.g. artificial pacemaker and cochlear implants.

Bionics – the replacement or enhancement of organs or other body parts by mechanical versions. Bionic implants differ from mere prostheses by mimicking the original function very closely, or even surpassing it.

There are a number of initiatives to improve prosthetics and reduce cost to produce

• Helping hand (video 4:05) – Daniel is a normal boy, he likes dinosaurs and tractors. But something makes him very special: curiosity, courage and an arm designed just for him.

• Prosthetics shouldn’t cost an arm and a leg – The Open Prosthetics Project is producing useful innovations in the field of prosthetics and freely sharing the designs. This project is an open source collaboration between users, designers and funders with the goal of making our creations available for anyone to use and build upon.

• Amputees can now program their own bionic hands. The latest i-limb comes with iPhone or iPad app that allows Koger to reprogram his hand with the touch of a stylus. He demonstrated by gripping an orange, a baseball and a can of soda. The i-limb allows fingers and thumbs move independently to conform around certain objects, said Ryan Spill, a prosthetist for Advanced Arm Dynamics’ new office in Philadelphia, who is working with Koger. The thumb is also motorized, not passive, as in previous prostheses.

• cochlear implant – a device that restores hearing to individuals with profound deafness. Cochlear implants are especially effective for children. If a person can’t hear during the first few years of life, the brain can’t fully equip itself to understand and acquire speech. Today, about 60% of implants worldwide go to children; those who live in an industrialized nation routinely receive them between age 1 and 2 years.

I want to hold your hand

Prosthetic tentacle – The limb would be able to grip many different objects by curling up with the help of a simple motor. It’s actually a pretty simple invention. The controls on the limb tell the motor to curl or uncurl, and there is no ‘hardwire’ link to the nervous system, as seen in some of the most advanced robotic or artificial limbs in development. The prosthetic functions as an assistant to the dominant functioning hand. The prosthetic needed to be both flexible and adjustable in order to accommodate a variety of different grips.

• Ask – What functionality would be really useful? How simple can it be?
• Imagine – What are some simple examples from nature that can do these tasks?

The motor winds one cable while releasing the other, causing the arm to curl. Releasing the cable will return the arm to its normal position.

• Design, Build – How can the prosthesis be operated? How can this device be activated? What materials are needed? How can the device be attached to the user?
• Improve – What changes would make the device easier to use? How can the device be more robust?

That’s engineering

• Apatite – a group of phosphate minerals. It is one of a few minerals produced and used by biological micro-environmental systems. Hydroxyapatite is the main component of tooth enamel and bone mineral.
• Titanium – a very strong metal. It does not corrode, and is resistent to sea water and chlorine. It is used in making the strongest and lightest parts of modern fighter jet planes and medical devices.

Engineering ideas

• adaptive, control, dexterity, grip

Do it
Now it is your turn. Here are some challenges for you to work on…
Mechanical hand project – made from drinking straws. Build a fully functional hand using only straws. The assembly is pretty simple. Yet, this design achieves fully mechanical hand that rebounds back to its original state when the tendons release their tension.

• Yorick, an interactive bionic skeleton that displays various implantable devices.
• Bionic Arm Design Challenge – Design and test a bionic arm, and see how it performs. A bionic arm combines robotics, biotechnology, and electronics to recreate the functions of the human arm. Advances in bionics can improve the lives of millions of people with lost limbs. In this challenge you will virtually design and test a robotic arm, and learn how engineers create working artificial arms. Discover the different components used to make a bionic arm. Test your arm against several criteria commonly used in the construction of real robotic arms. Work with a budget to choose the components you think will create the best arm, and see how it performs. requires Shockwave
• look at how animals handle objects. Design a prosthetic device that would use similar motions.

• ‘Terminator’ arm is world’s most advanced prosthetic limb (video 3:15) – hi-tech bionic hand – so precise he can type again. Terminator-like carbon fibre mechanical hand is controlled with movements in his upper arm. The bebionic3 myoelectric hand, which is also made from aluminium and alloy knuckles, moves like a real human limb by responding to muscle twitches. The robotic arm is so sensitive, he can touch type on a computer keyboard, peel vegetables, and even dress himself for the first time in six years.

Learn more…

• A Foot in Two Worlds – 3-D printing is creating new opportunities – and raising intriguing questions – as digital and physical realms meld – a 3-D scan of a Ugandan’s severed limb can be sent within seconds to another part of the world where a prosthetist can digitally design a replacement, sending that file back to Africa to be printed. Printers are increasingly sophisticated, capable of using a wide range of resins and polymers to create three-dimensional objects.
• Scientific advances in prosthetic limbs – Mind-controlled arm and hand, bionic knees and ankles. Engineered components used include actuators, gyroscopic sensors, load-sensing, artificial intelligence.
• simple biomechanical finger fabricated out of spare bicycle parts

• Prosthetic tentacle
• Revolutionizing Prosthetics – DARPA program developed two anthropomorphic advanced modular prototype prosthetic arm systems, including sockets, which offer increased range of motion, dexterity and control options.