Theoretical Evaluation of DE-AFO-1550: A Comfortable Robotic Ankle Exoskeleton for Children with Cerebral Palsy Powered by Advanced Stacked Dielectric Elastomer Actuators.

Cerebral palsy (CP), the most prevalent motor disorder in children, significantly impairs gait, often due to deficiencies in ankle control. Traditional ankle-foot orthoses (AFOs) used in CP management provide passive support but restrict natural ankle motion, resulting in muscle atrophy and limited adaptability. Powered AFOs, while offering propulsion assistance, are frequently bulky and uncomfortable, hindering long-term use. We designed an innovative, biomimetic AFO in our most recent study. Named DE-AFO, this device employs artificial muscles made from an electroactive polymer actuator called dielectric elastomer (DEA) to assist ankle movements in the sagittal plane. DE-AFO features a gait-phase detection controller that synchronizes the artificial muscles with the user's natural gait cycle, mimicking the behavior of biological muscles while maintaining a lightweight, compact, and silent design. This study builds upon the initial DE-AFO model by incorporating the latest version of the commercially available and stacked configuration of DEA (SDEA-1550), which offers enhanced force and displacement capabilities. Testing was expanded to include three participants with spastic diplegic CP to theoretically test and evaluate the updated DE-AFO's (DE-AFO-1550's) effectiveness in compensating for ankle moment deficits. The DE-AFO-1550 could fully compensate for dorsiflexion deficits (100 %) during the swing phase and address 75 % of plantarflexion deficits during the pre-swing. These findings highlight the DE-AFO-1550's potential as a nextgeneration, user-centered robotic AFO, capable of significantly improving mobility and quality of life for individuals with CP.