FES Brace with Variable Resistance Hinge for Dropfoot
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Solution Overview
Problem
Conventional treatments for drop foot, such as rigid ankle/foot braces and Functional Electrical Stimulation (FES), suffer from limitations like joint immobilization, muscle degeneration, and muscle fatigue, necessitating a more practical and effective solution for consistent stimulation and adjustable resistance.
Innovation Solution
A wearable FES brace with embedded sensors and a controller that provides controlled, intermittent stimulation of the peroneal muscles based on foot-ground interaction, featuring adjustable resistance and automatic locking to prevent fatigue, allowing for easy application and use without a physical therapist's intervention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a rigid ankle/foot brace is used to maintain the ankle in a neutral position, then the ankle stability is improved, but the ankle function is interfered with and soft tissue contracture risk increases
Solution Approach 1:
The brace incorporates a movable joint instead of a fixed rigid connection, allowing the ankle to dynamically adjust its position. The joint can be locked when stability is needed and unlocked to allow natural movement, resolving the contradiction between stability and function.
Solution Approach 2:
The brace uses periodic locking and unlocking mechanisms to provide stability during weight-bearing phases and allow movement during non-weight-bearing phases, enabling both stability and function through time-dependent control.
2Stability of the object's composition
If the ankle is fixed by the brace, then the ankle stability is improved, but the peroneal muscles degenerate and lose viability
Solution Approach 1:
The dynamic joint allows the ankle to move within certain ranges, providing mechanical stimulation to the peroneal muscles while maintaining stability when needed. This prevents muscle atrophy while ensuring joint stability during weight-bearing activities.
Solution Approach 2:
The brace incorporates sensors that detect ankle position and provide feedback to control the joint locking mechanism, ensuring the ankle remains stable during weight-bearing while allowing movement during non-weight-bearing phases to stimulate muscle activity.
3Reliability
If conventional FES is used to stimulate peroneal muscles, then muscle function is improved, but muscle fatigue occurs quickly
Solution Approach 1:
The FES system uses periodic stimulation patterns with rest intervals between stimulation cycles. This allows muscles to recover and avoid fatigue while maintaining functional improvement through repeated stimulation over time.
Solution Approach 2:
The system incorporates sensors to detect muscle activation levels and adjusts FES intensity accordingly, reducing stimulation intensity when fatigue indicators are detected to prevent muscle exhaustion while maintaining effectiveness.
4Device complexity
If conventional FES is used without microprocessor control, then the device complexity is reduced, but the stimulation consistency and optimization are insufficient
Solution Approach 1:
The brace incorporates automated electrode placement mechanisms and self-adjusting FES parameters that adapt to user needs without requiring manual adjustment or complex external control systems, maintaining simplicity while improving precision.
Solution Approach 2:
The system automatically adjusts FES parameters such as intensity and frequency based on detected muscle response and user activity level, optimizing stimulation effectiveness without requiring complex manual control mechanisms.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables improved ambulatory function by maintaining muscle condition and stability, allowing for rehabilitation through regular activities like walking, while preventing muscle fatigue and joint instability.
Implementation Method 1
a solenoid for locking the joint of the brace
Implementation Method 2
Functional Electrical Stimulation (FES) is a well-established field of research and its foundation is based on the fact that a muscle can be externally stimulated to contract by passing a current having a specific shape, strength and frequency through skin-electrodes overlying the muscle
Data Source
AI summary
A functional electrical stimulation brace responsive to various positions of an intended wearer's foot. The device includes a plurality of sensors positioned at different locations under the intended wearer's foot to detect the current position of the foot. Outputs from the sensors are fed to a controller that uses logic to activate an electrical stimulation unit that stimulates the peroneal muscles of a patient at the appropriate times during the patient's gait. The device may also employ mechanical stabilization of the ankle in addition to the functional electrical stimulation by means of an ankle foot orthosis with a variable resistance hinge. The electrodes are embedded in fixed locations in the brace upper portion so that optimal location of the electrodes relative to the peroneal muscles is maintained every time the device is applied. Also provided is a method for assistance and rehabilitation for a patient by electrical stimulation of the peroneal muscles. In the method, the position of the foot is detected and the peroneal muscles are stimulated responsive to particular positions of the patient's foot in order to activate the muscles at the appropriate times during the patient's gait. The device also provides lateral and torsional stability by means of the ankle-foot orthosis.