Dynamic mechanical assessment of prosthetic running blades using CNT fabric-based strain sensors

Running blades are sports prostheses used by individuals with lower limb amputation, constructed from fiber-reinforced polymer composites for superior strength-to-weight characteristics. These blades are designed to compress and decompress easily, enhancing athletic performance. However, a significant challenge in their design and use is the difficulty in precisely assessing their mechanical behaviour in vitro. This study explores the use of carbon nanotube (CNT) fabric-based strain sensors to dynamically measure strain on prosthetic blades. A sensor array and signal conditioning circuitry were developed and integrated into a C-shaped blade. The mechanical performance was tested under various conditions, using ANSYS simulations to identify critical stress points. Dynamic data acquisition was achieved through Wi-Fi modules, allowing for detailed analysis of strain distribution during different activities. Sensors were mounted on heel, toe and middle regions of prosthetic blade to test its performance. Various striking trials were performed for different strike locations to imitate different human motions. The results demonstrate that CNT fabric-based sensors provide insights into the strain behaviour of prosthetic blades. Our findings indicate that the strain distribution varies with strike location, with the middle section experiencing the highest strain during flat base strikes while heel and toe strikes exhibit relatively lower strain levels. This strain analysis paves the way for improved design optimisation and customisation of running blades.