Low-power sensor module for long-term activity monitoring

Area of Science:

• Biomedical Engineering
• Rehabilitation Technology
• Wearable Sensors

Background:

• Wearable sensors offer potential for long-term functional motor activity assessment and therapy transfer studies.
• Existing systems often have limited sensing capabilities or are not designed for extended monitoring.

Purpose of the Study:

• To present ReSense, a novel miniature sensor unit optimized for long-term monitoring of functional activity.
• To evaluate the capabilities of ReSense in capturing detailed movement data and distinguishing specific daily activities.

Main Methods:

• Development of a miniature sensor module (Ø25 × 10 mm, 10 g) integrating inertial MEMS sensors (6 degrees of freedom) and a barometric pressure sensor.
• Implementation of an integrated memory card for data logging and a power-management system for extended operation.
• Continuous recording at 25 Hz (27 h) and 100 Hz (22 h), with inactivity detection extending operational time by approximately twofold.

Main Results:

• The ReSense module successfully recorded functional activity data over extended periods.
• The barometric sensor enabled identification of activities involving altitude changes (e.g., stairs, elevators).
• Combined analysis of inertial and barometric data allowed differentiation between stair climbing and elevator use.

Conclusions:

• ReSense is a compact, long-term capable wearable sensor system for functional activity monitoring.
• The sensor's ability to differentiate altitude-related activities enhances its utility in real-world settings.
• This technology can advance the assessment of motor function and therapy effectiveness in daily living.