Enabling the ActiGraph GT9X Link's Idle Sleep Mode and Inertial Measurement Unit Settings Directly Impacts Data...

Area of Science:

• Biomedical Engineering
• Wearable Technology
• Data Acquisition

Background:

• The ActiGraph GT9X is widely used in clinical trials for physical activity and sleep tracking.
• Incidental findings highlighted a potential interaction between the device's idle sleep mode (ISM) and inertial measurement unit (IMU).

Purpose of the Study:

• To investigate the interaction between the ActiGraph GT9X's ISM and IMU.
• To assess the impact of this interaction on accelerometer data acquisition.
• To inform researchers about potential data anomalies.

Main Methods:

• Utilized a hexapod robot to test the X, Y, and Z sensing axes of GT9X accelerometers.
• Tested seven GT9X devices across frequencies from 0.5 to 2 Hz.
• Evaluated three setting parameter combinations: ISM ON/IMU ON, ISM OFF/IMU ON, and ISM ON/IMU OFF.

Main Results:

• Setting Parameters 1 (ISM ON/IMU ON) and 2 (ISM OFF/IMU ON) showed no significant difference in outputs.
• Both Setting Parameters 1 and 2 yielded significantly different results compared to Setting Parameter 3 (ISM ON/IMU OFF).
• The ISM was observed to be active only during Setting Parameter 3 tests, despite being enabled in Setting Parameter 1.

Conclusions:

• The interaction between ISM and IMU settings significantly affects ActiGraph GT9X data acquisition.
• Researchers must be aware of these specific setting interactions to ensure data integrity.
• Recommendations are provided for optimizing GT9X usage in research settings.