Developing bespoke breathable prosthetic liners with growth tracking & active cooling

The interface between a residual limb and a prosthetic requires a liner material that ensures the transmission of forces while ensuring comfort and preventing skin damage. This is a considerable engineering challenge because a prosthetic wearer's body changes size and shape throughout the day. In the case of children there is another complicating factor, growth, which over time changes the fit of the prosthetic and the liner. Skin damage occurs due to a number of factors including temperature, exertion, hydration levels, and shear & pressure forces due to poorly fitting liners, slippage and misalignment. 

Our proposed solution is a bespoke silicone liner that is printed using a multi-print head 3D syringe printer, which does not require any intermediary moulds to be produced, thereby reducing the time and material cost of manufacture. The liner will be printed in one piece containing breathable porous structures throughout the liner, along with active cooling channels that can circulate coolant/water to exterior heat dispersion panels. The extra complexity this implies is one of the reasons to use this 3D  printing technology, because once digitally designed, it is no more complicated to print than any other object. In the liner stages of the project we will also include a grid of concentric stretch sensors that can monitor both the daily change in size and volume of the stump, but also the long-term growth of a child’s stump to inform update scheduling of refitting prosthetic devices. The liner will be algorithmically designed using surface 3D scans of the child’s stump, which can be done extremely quickly compared to making a mould. This scan will then inform the digital topology on to which our composite silicone design can be mapped and printed in one piece. Potentially this could reduce the whole manufacture process to less than a day. Such active intelligent liners managed by prosthetists could lead to better fit and better management of comfort and skin health of the prosthetic wearers.

This project is being jointly led by researchers and clinicians at UCL and the Royal National Orthopaedic Hospital in Stanmore. The team includes Prof Mark Miodownik (UCL Mechanical Engineering/Institute of Making), Dr Catherine Holloway (UCL Computuer Science), Prof Rui C.V. Loureiro (UCL Institute of Orthopaedics and Musculoskeletal Science), Dr Imad Sedki (Consultant in Rehabilitation Medicine, Royal National Orthopaedic Hospital), Mark Croysdale (Senior Prosthetist, Royal National Orthopaedic Hospital), and Ben Oldfrey (PhD student, UCL COMPLEX). It is an extension of Ben Oldfrey's research on Developing bespoke flexible sensors for prosthetic and orthotic liners. This new research is funded by the Starworks Innovation Project - a young people’s prosthetics research collaboration which brings children and their families together with key opinion leaders from the NHS, Industry, Clinical Academia and leading National Research Centres with capabilities in child prosthetics.