High Density Surface Profiling of Multi-layer Soft Actuator Arrays for Use in Prosthetic Sockets

The fit of a prosthetic socket is a critical factor in designing a comfortable socket. The socket fits depend primarily on residual limb volume fluctuation and pressure distribution over the residual limb. Using soft actuator arrays is a recent method to improve the socket fit by compensating for the residual limb volume fluctuation and controlling pressure distribution over the residual limb. However, there is currently no study to investigate the design of an inexpensive soft actuator array and measure the surface deformation field of the soft actuator array when it comes in contact with the residual limb.In this study, we propose a multi-layer soft actuator array to be embedded into the prosthetic socket. We used a new sub-pixel image registration algorithm to measure the soft actuator array surface deformation with 50 μm accuracy. We measured 90 different soft actuator array surface deformations by changing the actuator input pressures and actuating different actuator layers of soft actuator arrays.Our study demonstrated that soft actuator arrays can control the pressure distribution over the residual limb, and the input pressure to the actuators can be used to compensate for residual limb volume fluctuations.