In the case of lower-limb amputation, peripheral sensations are severely attenuated through an artificial prosthetic limb during gait. While crude pressure sensations can be detected between the residual limb and socket interface, this feedback is imprecise compared to a healthy limb. A sensory feedback system has been developed to provide a form of auxiliary lower limb sensory feedback. It is believed that this technology can impact gait by providing feedback regarding changing prosthetic plantar pressures during each step.

This system was composed of (1) flexible force sensor system to monitor plantar pressures at the prosthetic foot, (2) system control electronics, software and pneumatics and (3) pneumatically controlled silicone balloon actuators to provide tactile feedback to the user. Sensory feedback is provided via mechanical deformation of the skin and the stimulation of slowly adapting mechanoreceptors to resist effects of sensory adaptation. Actuators were arranged to provide a sensory mapping of the prosthetic foot about the residual limb.

Human perceptual testing was performed to optimize and validate actuator design feasibility, where it is shown that 12 mm diameter balloon elements can be detected with high accuracy. Biomechanical gait analysis was performed to evaluate the research hypothesis: the application of this sensory feedback system will provide quantifiable impacts to the gait performance of subjects of lower-limb amputation. Seven unilateral transtibial amputee subjects were analyzed using infrared positional markers while wearing the sensory feedback system in two conditions: baseline and with feedback. An analysis of recorded gait measurements yielded statistically significant effects on subject gait. These effects include, increased walking velocity and cadence, increased weight bearing on the prosthetic limb, reduced walking stance asymmetry, and effects on joint (hip, knee, ankle) angles and moments. These findings suggest that the application of intuitive sensory feedback system can impact the walking performance of persons with lower-limb amputation.