Summer 2025: Design and Results of a Variable Stiffness AFO with a Tunable Joint Mechanism

Affiliations: College of Engineering and Computer Science
Team Leader:
Sy Nguyen
sy.nguyen@ucf.edu
Mechanical Engineering PhD
Faculty Mentor:
Hwan Choi, PhD
Team Size:
3
Open Spots: 1
Team Member Qualifications:
Third year of mechanical and aerospace engineering
Description:
The overall objective of this proposal is to finalize the engineering of such a dynamic, adaptive and next-generation AFO where we hypothesize that the proposed expandable mechanism based AFO’s device will provide equivalent assistive performance to traditional coil-spring AFOs, with the added benefit of adaptive tunability and a lighter overall weight. Our long-term goal is to demonstrate the efficacy of the developed orthotic solution through mediated clinical trials, using the resulting data to support our efforts bringing it to market. Orthomerica Products Inc. (OPI) is a Florida small business, which will support this effort with their 35+ years of orthotics manufacturing experience. Their expertise in manufacturing orthotics and prosthetic devices is enhanced by their commitment to hiring experienced O&P clinicians. To bring novel research to the marketplace, OPI has established partnerships with R1 research faculty who have developed a next-generation assistive device for AFOs. Co-PIs Charles Didier, Ph.D. (OPI) and Hwan Choi, Ph.D. (University of Central Florida, UCF) lead the project. Dr. Didier’s industrial experience at OPI, combined with his prior academic research experience, and Dr. Choi’s Rehabilitation Engineering and Assistive Device Lab (REAL), position the team to develop the proposed novel AFO that meets the necessary requirements to address a marketplace gap, while incorporating critical input from key clinical personnel. This Phase I study focuses on two primary aims to facilitate the successful translation of this research into the marketplace: Aim 1: High-energy efficient, compact and light weight adjustable stiffness AFO. We will develop an AFO which enables prompt stiffness changes with compact size and lightweight by adopting simple expandable mechanism that overcomes the bulky, heavy, and slow stiffness adjustment speed state-of-the-art AFOs. To determine optimal design that maximizes the range of stiffness and the level of energy return, we will use a structural finite element-machine learning based design optimization. Our developed energy recycling mechanism allows for a compact, variable stiffness AFO, with a highly efficient energy return which we will assess using our Ankle Assistive Device Stiffness (AADS) test. Led by PI Drs. Choi Aim 2: Integration of saddle spring into to AFO towards feasibility manufacturing. In concert with Aim 1, we will adapt the elastic beam design for scalable, and feasible manufacturing. Key clinical personnel at OPI will engage with the PIs to evaluate the expandable mechanism based AFO prototypes for their current efficacy, as well as for their requirements to implement in an AFO manufacturing setting. Additionally, the team will produce initial commercial-style prototypes for preliminary evaluation, and eventual use in Phase II. Led by PI Dr. Didier. The expected outcome of this Phase I STTR is the establishment of translational manufacturing specifications for prototype AFOs. A Phase II STTR will then focus developing the AFO care framework, through machine learning-based algorithms neuromuscular rehabilitation with the developed AFO. As a result, clinical trials will be conducted to assess the effectiveness of the AFO care framework in assisting patients with neurological disorders who have walking mobility issues. The proposed AFO technology herein has significant potential for broad impacts on individuals with walking difficulties.