• prosthetic leg

    SOURCE

    September 2016

    (Nanowerk News) The carbon fibre legs or “blades” used by lower limb amputee runners have arguably become one of the most iconic symbols of the Paralympic Games. Although different lower-limb sports prostheses are used for running, jumping and other activities, they share a single common aim: they are designed to help Paralympians run faster, jump higher or further than other competitors. Form follows function.

    For those who have prostheses for more everyday uses, however, their replacement limbs need to be able adapt to different scenarios and perform a variety of functions, not just excel in one discipline – just like an actual leg. So how can we make prostheses feel more like the real thing rather than a specialist tool?Whereas modern running blades have a distinctive hook shape, one of the most promising engineering approaches for everyday prostheses is to closely model the biological design of a leg, ankle and foot. This approach is referred to as “biomimicity” (“Biomimetics: lessons from nature–an overview”).A “passive” ankle-foot prosthesis generally uses elastic like a spring to replicate the behaviour of the Achilles tendon, storing elastic energy and releasing it before ankle push-off. “Active” prostheses additionally use an actuator or motor to make up for the power previously provided by the calf muscle at every step. Such prostheses have been shown to help users walk more like a non-amputee and improve symmetry between the biological and the artificial limb. At the moment, this mainly applies to walking overground at steady speeds rather than activities such as climbing stairs

    Simple design, advanced technology

    Other ways to make a prosthesis more like a biological leg and improve the user’s comfort are more simple. They also illustrate how important it is to involve the amputee in the design process. One user of the most advanced bionic ankle currently available told me its greatest feature was not that it provided a powered push-off or that it allowed them to walk more like a non-amputee. Instead it was that the foot dropped flat on the ground when sitting with an outstretched leg, rather than sticking up awkwardly at a 90-degree angle (as is the case for the majority of prosthetic feet).Another issue is how the prosthesis is controlled. Active prostheses now include on-board computers to control the motors and emulate human walking. Prostheses are effectively becoming more and more like wearable robots. What’s more, we can even use interfaces that read signals from the brain or muscles (“Robotic Leg Control with EMG Decoding in an Amputee with Nerve Transfers”) so that the user can operate the prosthesis like a real leg just by thinking and moving in their normal way (“Volitional control of ankle plantar flexion in a powered transtibial prosthesis during stair-ambulation”).


    An amputee feels rough or smooth textures in real-time — with his phantom hand — using an artificial fingertip connected to nerves in the arm. The advancement will accelerate the development of touch enabled prosthetics.
    The next step being trialled is the use of implantable electrodes that send signals to the brain to give the user tactile feedback so they can feel the contact on the prosthesis as if it were their biological limb, closing the human-machine loop.These technological and scientific advances connect the amputee more intimately with their prosthetic limb, meaning we can now focus more on how the prosthesis is embodied. In other words, to what extent does the prosthetic limb feel like part of the biological body? Does your brain treat it as such?We have a good understanding of how our body is mapped in our brain. Both our motor cortex – the movement control centre, if you like – and the somatosensory cortex where we process a wide range of touch sensations are organised somatotopically (“Somatic Motor and Sensory Representation in the Cerebral Cortex of Man as Studied by Electrical Stimulation”). This means each area of our body corresponds to a specific area of the primary motor and sensory cortices. Importantly, this mapping does not disappear after the loss of a limb.This means we have an opportunity to connect prostheses, through muscles and peripheral nerves, to the parts of the brain that would have controlled and sensed the biological body part. But it may also allow us to measure embodiment (“Engineered embodiment: Comment on “The embodiment of assistive devices—from wheelchair to exoskeleton” by M. Pazzaglia and M. Molinari”), how successfully the brain accepts the prosthesis as part of the body.Ultimately this line of research, bringing together cognitive neuroscience and biomedical engineering, is not only important for designing better prostheses. It is a unique window for understanding how our brain creates and maintains the image of our bodies – mechanisms that apply equally to amputees and non-amputees.

    Source: By Oliver Alan Kannape, Assistant Lecturer, University of Central Lancashire via The Conversation

    Read more: Artificial limbs are becoming more like wearable robots (w/video)

     
     

    No comments

    Be the first one to leave a comment.

    Post a Comment


     

     

    Latest Posts

    Latest Video

     
     

    LATEST POSTS

    Chinese company Jala Group using 3D printed skin to test cosmetics for Asian market

    SOURCE Jala Group, a Chinese cosmetics company, has used 3D bioprinting technology to print artificial “Asian skin,” complete with dermis and…

    Historic HIV vaccine efficacy study underway in South Africa

    The first HIV vaccine efficacy study to launch anywhere in 7 years is testing whether an experimental vaccine safely prevents…

    When Pot Meets Pain and Insomnia: Why Many Fibromyalgia Patients Swear by Medical Marijuana

      Fibromyalgia is a painful condition that over three million Americans suffer from. It causes widespread muscle pain and tenderness…

    Nanoarray sniffs out and distinguishes multiple diseases

    SOURCE “Diagnosis and Classification of 17 Diseases from 1404 Subjects via Pattern Analysis of Exhaled Molecules” ACS Nano Before modern…

    Cardiac stem cell infusion could be effective therapy for the most common type of heart failure

    SOURCE Cardiac stem cells could be an effective treatment for a common but difficult-to-treat type of heart failure, a new…

    Outer layer of human heart regrown using stem cells

    Human stem cells have been used to regenerate the cells that cover the external surface of a human heart(Credit: DarioStudios/Depositphotos) SOURCE…

    Gastrogenomic delights: A movable feast

    SOURCE The complete genome sequences of Escherichia coli and Helicobacter pylori provide insights into the biology of these species Recently,…

    Glaucoma gene therapy on positive trajectory using CRISPR-Cas9

    SOURCE May 02, 2016 Seattle—Results from a series of preclinical studies are providing proof of principle that gene targeting using…