Transcript - Functionally graded prosthetic liners - Ben Oldfrey

I'll be giving a quick overview of our project, 'Algorithmic design of functionally graded prosthetic liners', which is a collaboration between groups at University College London, University of Southampton and Radi devices. So in prosthetics and orthotics, the use of digital manufacturing is rapidly accelerating -  really exciting things are happening. However, it's still focused on the rigid material, prosthetic componentry that's available. And the thing is that, that we're soft. And we're interested in what we can do in terms of soft technology. The interface between the residual limb and the socket, or as it's often called the stub-socket interface, it still presents a lot of challenges around comfort, fit. And more and more people ubiquitously are wearing softer, less (indistinguisable) liners between the socket and the limb, that help to reduce shear stress on the skin, increas comfort, and they just put particular areas that give a high cushioning effect on the bony prominences. But how could these be improved? Particularly maybe, thinking about people that have residual limbs with troublesome topologies that, shapes that are difficult to fit for prosthetists and might be heavy scar tissue, or the residual limb volume varying greatly. I mean, they do daily, they do seasonally. But what can be done? So next slide, please. So looking to nature, let's think about those tissues that are actually in the residual limb, or other parts of the body or the parts of nature, well, Nature creates these incredible interfacing mediums between hard and soft materials in the body, by grading between the connecting tissues, for different reasons in different places. And thinking about our problem, well, this grading of tissue, what it does is it spreads the stresses being translated to rather than concentrating stress at a specific point, it spreads it across that interface, which, has potential to increase the possible front force transfer at an interface and reduce the tolerance to damage because it isn't creating these maximum stress, or  the interface between different components within the device, and then on to the residual.  So additive manufacturing allows for us to think about these things with multi material, printing structurally complex products that we couldn't previously create. And so we're really interested if we can incorporate these ideas into the technology for the stumps interface. We want to look at ways of potentially making bespoke optimised material properties across the interface that could be created for the various tissues of the residual limb. So this could be grading perpendicular to the interface, although thin. That's one area that we were really interested in exploring, potentially really creating very, very soft materials up against the residual limb. And otherwise something more akin to the  socket at the other side. But we want to explore whether that's  the right question to be asking. And also,  if there's parallel to the limb, if there's different tissue properties around the surface of the residual limb. But really exciting is to be able to think about programming the material properties of the liner interface, dictated by the local properties of the residual limb, the needs of the user, and their use type. Running, for example, presents different problems within the socket, as opposed to walking or otherwise. And so really, along with these new ways of manufacturing, across the board, for all components, really, we need newly applicable repair strategies, we need to devise these if we're not really going to be exacerbating what is also a real problem in the repairability of these devices. For liners, repair barely happens at all. And that's okay, maybe in some settings, but for the liners, these are replaced once or twice a year, it could be more more frequent than that; this adds up to a great amount of waste and expense over the lifetimes of users. And if we're thinking about more advanced technologies, we need to be reducing  the value in the cost that we're putting into that;  we need to be fixing these things, rather than just throwing away something more expensive. And at the simpler end of simply allowing a product to be available to somebody in low resource settings, well this continued use of the device, it puts up huge barriers to potential users in low resource settings. And if we can be fixing something and creating efficiencies and costs and that can open up line of technologies in these settings and it also has a knock on effect to other socket technologies, for example, that require a liner to work. So, therefore building on the materials development work that we've done at UCL and soft materials structures and liner technology, and exciting predictive socket design and modelling work that's been done at University of Southampton, and the now spin out company Radi Devicesevices, we aim for the following with this project:  we want to model and produce new functionally graded material interfaces, for improved comfort to the socket interface, along with developing repair strategies to match these advanced manufacturing techniques. The objectives are to fabricate a set of novel graded patches, model the socket interface with respect to optimising the stress profile, develop a device-level custom testing line at implementing these developments, and finally, look at a repair and maintenance techniques appropriate to the material structures. That's our team there - myself, and Alex and Alison and Joshua will report back when we've made some progress. Thanks very much.