A Novel Capacitive Step Sensor to Trigger Stimulation on Functional Electrical Stimulators Devices for Drop Foot

Area of Science:

• Biomedical Engineering
• Rehabilitation Technology
• Gait Analysis

Background:

• Drop foot, a common post-stroke condition, affects millions annually, impacting mobility.
• Functional Electrical Stimulation (FES) is a key treatment for drop foot, requiring precise gait phase detection for optimal efficacy.
• Existing methods for gait phase detection lack the real-time accuracy and reliability needed for synchronized FES.

Purpose of the Study:

• To develop and validate a novel step sensor for real-time gait phase detection.
• To synchronize FES therapy with the user's gait cycle for improved drop foot management.
• To enhance the accuracy, reliability, and comfort of gait phase detection systems.

Main Methods:

• A custom capacitive pressure sensor array integrated into a heel-worn step sensor was designed.
• The system acquires sensor signals, processes them with a real-time algorithm to identify gait phases (start/end of swing phase).
• Wireless transmission of synchronization signals and testing with healthy volunteers on a treadmill and during walking tests.

Main Results:

• The proposed step sensor achieved 100% sensitivity and specificity in detecting 1342 steps across various conditions.
• Demonstrated significantly improved time error compared to other pressure sensors and lower-back inertial sensors.
• The system showed high accuracy in detecting the start (27.60±0.03 ms) and end (20.86±0.02 ms) of the swing phase.

Conclusions:

• The novel heel-based capacitive pressure sensor offers a highly accurate and reliable solution for real-time gait phase detection.
• This technology enables precise synchronization of FES for drop foot, enhancing treatment effectiveness and patient comfort.
• The system represents a significant advancement in wearable technology for stroke rehabilitation.