Assist-Knee: Energy Harvesting for Sit-to-Stand-to-Sit Transitions

PROJECT SUMMARY This SBIR Phase I project will create and evaluate a novelproof of concept low tech Energy Harvesting Knee Prosthesisor Assist Knee Prosthesiscapable of helping geriatric individuals with transfemoral limb loss more effectively and safely perform sit to stand to sit transitionsTransitioning from a sitting to a standing position is much more difficult for an individual with transfemoral limb lossespecially within the geriatric populationdue to declining or absent knee and ankle musculatureWhen rising from a chairthese individuals heavily rely on their sound limb and upper limb strength to lift their body weightGeriatric prosthesis userswho often have marginal and declining strengthcould retain their independence if a prosthetic knee was capable of assisting with sit to stand to sit transitionsUnfortunatelythe current designs of most commercially available prosthetic knees do not assist with the sit to stand to sit transitiona task that is fundamental for normal activities of daily livingThe Assist Knee design harvests the prosthesis userandapos s potential energy during the stand to sit transition and appropriately returns that energy to assist with the sit to stand transitionWhile harvesting energyAssist Knee provides a resistive knee extension moment that imitates eccentric contraction of the quadriceps muscles for a controlled stand to sitThe return of energy provides knee extensionimitating concentric activity of the quadriceps musclesfor an assisted sit to standThe technological innovation of this design does not require a large motorbatteryor complex system to provide external power for knee extension assistOur low costlightweight design is an alternative to externally powered prosthetic devicesSince external power is not being added to the systemAssist Knee is not intended to replicate maximum moment output at the knee but to provide a useful percentage of knee extension moment to assist with initiation of the sit to stand transitionThe specific aims of this project involvedesigning and constructing Assist Kneeperforming bench testing of the deviceand evaluating the proof of concept Assist Knee in prosthesis usersSuccessful design and implementation of the proof of concept Assist Knee will enable geriatric individuals with transfemoral limb loss to more easily complete sit to stand to sit transitionsincrease independence by reducing the need for caretaker assistanceand help control the lowering of a user during the stand to sit maneuverThe commercial application of Assist Knee is a low costlightweight prosthetic alternative to assist individuals with transfemoral limb loss within the geriatric population to independently complete activities of daily living PROJECT NARRATIVE Geriatric individuals with transfemoral limb loss often have difficulty performing the sit to stand to sit transition and could benefit from assistance at the knee joint to make activities of daily living easierWe propose a novellow tech energy harvesting knee prosthesisor Assist Kneeto help these individuals by harvesting the prosthesis userandapos s potential energy during the stand to sit transition and appropriately returning that energy to assist with the sit to stand transitionThis Assist Knee project will enable geriatric transfemoral prosthesis users to more easily complete sit to stand to sit transitionsincrease independence by reducing the need for caretaker assistanceand help control the lowering of a user during the stand to sit maneuver