Developing bespoke flexible sensors for prosthetic and orthotic liners.

The interface between a residual limb and a prosthetic or an orthotic requires a liner material that ensures mechanical transmission of forces while ensuring comfort and preventing skin damage. This is a considerable engineering challenge because the body changes size and shape throughout the day due to a number of factors including temperature, exertion, hydration levels, ect. These lead to a change in the pressure and shear forces acting on the skin which can cause a range of skin disorders and lead to chronic skin problems. This project aims to address these problems by providing a liner material that can sense these forces providing this data as realtime feedback to the user allowing them to prevent their skin becoming damaged and to manage their condition.

Our technology combines existing stretchable sensors with realtime computation to create an intelligent system that adapts to the user allowing them to monitor the vulnerability of their skin to damage. We have preliminary data that shows this approach has real potential, and this grant will allow us to produce a prototype of the technology in collaboration with the Global Disability Innovation Hub (www.disabilityinnovation.com). The grant will also allow us to make available online a fully open source toolkit to allow others in the Vulnerable Skin Network to build upon and apply this system to other applications.

Our approach is to create a smart liner material for a prosthetic or orthotic that can measure complex stress states giving realtime feedback to the user. There are two major problems holding back production of such a material. Firstly, the damaging forces are 3D comprising normal pressure, stretch & shear stresses, however existing technology is currently unable to capture this complex stress state in real time. Secondly, liners must be bespoke for each user, so the intelligence in the liner must also be bespoke to that user which is technically extremely challenging.

This six-month project is funded by the Medical Devices and Vulnerable Skin Network, and led by PhD student Ben Oldfrey (UCL COMPLEX), the project also works collaboration with Prof Mark Miodownik (Institute of Making), Dr Cathy Holloway (UCL Computer Science) and the Global Disability Hub.