A Wearable, Multi-Frequency Device to Measure Muscle Activity Combining Simultaneous Electromyography and Electrical...

Area of Science:

• Biomedical Engineering
• Rehabilitation Technology
• Wearable Sensors

Background:

• Surface electromyography (EMG) is widely used for muscle contraction detection but struggles with accurate muscle force estimation due to unpredictable factors.
• Electrical impedance myography (EIM) offers a complementary approach by measuring changes in electrical impedance during muscle activity, showing promise for muscle function analysis.

Purpose of the Study:

• To design, develop, and evaluate a novel wearable device capable of simultaneously acquiring both EMG and EIM data.
• To create a robust system for measuring muscle conditions, mitigating artifacts often encountered with single-modality approaches.

Main Methods:

• A modular, wearable, and wireless device integrating separate EMG, EIM, microcontroller, and communication modules.
• The EIM module measures bioimpedance (20-200 Ω, <5% error at 140 SPS, <1000 ms settling time).
• The EMG module captures signals (20-150 Hz, 1 kSPS, 67 dB SNR) processed by an ARM-Cortex M3 microcontroller and transmitted wirelessly (868 MHz, 500 kbps).

Main Results:

• The developed device successfully integrates EMG and EIM functionalities in a compact, wearable form factor.
• Performance metrics for both EIM (accuracy, settling time) and EMG (frequency range, SNR) modules meet design specifications.
• Preliminary in-vivo tests during leg extension, walking, and sit-to-stand movements demonstrated the system's potential.

Conclusions:

• Simultaneous EMG and EIM measurements provide a more robust method for assessing muscle function compared to EMG alone.
• The developed wearable system shows significant potential for applications in robot-assisted rehabilitation and muscle condition monitoring.
• This integrated approach can lead to more accurate and reliable data for personalized rehabilitation strategies.