• Question: Would a metal robotic limb harm your body?

    Asked by MrTomTheNewABomb to Ted, S. S., Laura, Kevin, Ellen, Andrea on 4 Mar 2019.
    • Photo: Andrea Pacheco

      Andrea Pacheco answered on 4 Mar 2019:

      Our bodies are designed to muffle small impacts when we move. If we walk liquid cushions in our joints will smooth the impact and give a little freedom to the bones to move.

      A robotic limb might be too heavy and hard, but if you manage to make it smart enough with plenty of springs to cushion the movement and if you manage to make it translate by its own (meaning you do not need to pull and push) it could work.

      It is always better to mimic our body structure since it would be also easier for us to adapt to the device.

    • Photo: Laura Farina

      Laura Farina answered on 4 Mar 2019:

      Every thing we “connect” or implant in out body should be compatible with it. Our body should feel it as “natural”. Metal could not be the best solution because it can cause inflammation, but engineering today has made materials that can well integrate with our body.
      So I would say that part of the limb can be metal (not a heavy one) but other parts no and that would be fine.

    • Photo: Ted Burke

      Ted Burke answered on 4 Mar 2019:

      I think Andrea and Laura have answered your question, but I just wanted to add a couple of things you could look up if you’re interested in this area. There’s a whole emerging area called “soft robotics” in which we use soft, squidgy, pliable, flexible or bendy parts to build robots that can interact with people and with their surroundings in a safer way. In some cases, even the “actuators” (the components that produce the physical movement) are made of soft materials. This area may help with the development of future prostheses.

      Another interesting thing to look at is what they call “osseointegration”. This is a way of grafting a titanium rod directly onto the bone in an amputated limb (usually a leg). The metal rod extends out the end of the stump and a prosthetic limb can be attached to it. The surface of the metal rod has a specially designed porous surface so that the skin can heal properly about it. The massive advantage of this approach is that the weight of the person standing on the prosthetic limb is transferred directly to the skeleton, which is much more comfortable that resting your weight on the skin that covers the stump in a normal prosthesis. This has only become possible in recent years due to advances in how they engineer the surface of the metal implant.

    • Photo: Kevin OBrien

      Kevin OBrien answered on 5 Mar 2019:

      This isn’t really my area of expertise.
      I thought there were certain techniques that allowed bone to fuse to certain types of metals.
      There are also coatings that can be applied to make metals biocompatible, such as in the case of implanted devices, which are hermetically sealed in a metal can.

      I think that if a particular metal was selected as the ideal material for a robotic limb for a structural or other reason, the other issue could be overcome.

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