SBIR-STTR Award

This project seeks to develop an orthotic knee joint system that includes a non-linear torsion spring coupled with a novel concept called Morphological Switching (MorS) that changes the mechanical properties of the joint in response to user behavior. The research objectives are to prototype and functionally test the medial side of a Morphological Switched Orthotic Joint (MSOJ) assembly. Tasks include: a) fabricate and test prototypes of all joint components; b) mechanically integrated all prototype joint components and functionally test the MSOJ with control algorithms; and c) the MSOJ will be tested to assess functional benefits. Telemetry data will be collected during 200 steps at slow, medium and fast walking speeds and descending 200 stairs and be processed with a program that assesses biomechanical benefits. We expect the results to provide convincing quantitative proof of the ability of the MSOJ to create an energy efficient knee brace. The intellectual merit of the proposed project stems from the application of MorS to take the springs in the system, which are clearly passive, and allow the user to perceives the springs as having a dynamic stiffness whose behavior changes dependent on what the user does. The broader impact / commercial potential of this project stems from its impact on the estimated worldwide population of 150 million people who have mild/moderate walking dysfunction not currently addressed by any existing orthosis device. MSOJ offers new biomechanical benefits to this population group including adapting to whatever leg strength the user provides, adapting to the user selected speed and step length, reducing the effort needed to walk, providing complete torso support while ascending and descending stairs and preventing falls due to knee collapse resulting from insufficient leg strength. Novel technologies introduced include a synthesis methodology for designing non-linear hardening spring, actuators that need no battery energy to generate holding forces, sensors for measuring gait parameters and a distributed fault tolerant electronics architecture. The orthoses created with MOSJ would be the first assistive appliance that stores all sensor data and enables real time and/or background access of the data. These joints are expected to allow rehabilitation therapy to be delivered and monitored in remote settings during all Activities of Daily Living. MOSJ components will also be made available to researchers to allow fabrication of custom appliances for their rehabilitation research.

This Small Business Innovation Research (SBIR) Phase II project aims to create a leg brace that addresses the underlying causes of mild/moderate walking dysfunction affecting 150 million people worldwide. Novel brace elements called Morphologically Switched Orthotic Joints combine field-adjustable, non-linear torsion springs with microprocessor controlled clutches to change the brace's mechanical state dynamically according to the user's gait. Internet updatable software, executing under a multi-processor, fault tolerant brace operating system, samples the brace's 40 sensors to monitor leg posture and activate clutch state transitions. Novel brace concepts include soft/flexible tissue interfaces that adapt to brace misalignment, a joint configuration that provides greater range of motion compared with existing braces, and a fitting scheme with potential for self-fitting capability. Three research objectives are planned: optimize the brace design for comfort level while minimizing interference with Activities of Daily Living (ADL); build/test five prototype braces; and conduct human subjects testing with disabled volunteers to assess brace safety and benefits. Primary biomechanical benefits include dynamically adapting to the user's leg strength to provide full support at all knee angles and reducing the total force across the knee joint by up to an order of magnitude during mobility activities. The broader impact/commercial potential of this project stems from creating a brace that offers biomechanical benefits that substantially surpass those of existing devices without interfering with non-mobile ADL. Anticipated benefits include: allowing Knee Osteoarthritis (KOA) patients to walk with less pain; improving walking/stair-descent safety; adapting to the user's preferred step-length/walking-speed; reducing the effort needed to walk; and allowing a full day of mobile ADL (including a 20-mile walk) on a single battery charge. This will have a transformative effect on the existing leg brace market (120K offloading braces/yr alone) and improve Quality-of-Life for as much as 40% of the world's population suffering mobility dysfunction. The benefit for KOA patients includes a new treatment alternative for multicompartmental or obese KOA patients or for patients who cannot have knee replacement surgery. The benefit for walking/stair-descent safety includes potential for reducing the incidence of falls. Falling accounts for two thirds of accidental deaths and is the leading cause of restricted activity days amongst America's elderly; persons with leg weakness have a four- to fivefold increased risk for falls; directly addressing leg weakness therefore has potential to increase longevity and reduce healthcare spending.