Heart Rate Measurement Using the Built-In Triaxial Accelerometer from a Commercial Digital Writing Device.

Area of Science:

• Biomedical Engineering
• Wearable Technology
• Signal Processing

Background:

• Wearable technology provides accessible health data through smart devices, enabling continuous monitoring.
• Electrocardiograms (ECGs) and photoplethysmographies (PPGs) are clinical standards for heart monitoring.
• Accelerometers in wearables can estimate heart rate and filter noise from movement artifacts.

Purpose of the Study:

• To compare heart rate data from a commercial smart pen's accelerometer with standard ECG readouts.
• To validate the accuracy of a smart pen's built-in sensors for heart rate estimation.

Main Methods:

• Heart rate data was extracted from the accelerometer of a STABILO DigiPen.
• Data was collected from eight volunteers writing continuously for five minutes.
• Signals were processed using a Butterworth filter; comparisons were made against reference ECG data.

Main Results:

• The smart pen achieved a mean-squared error (MSE) better than 6.685 × 10-3 for time-between-pulse (Δt) calculations.
• Timestamp correlations between the pen's signal peaks and ECG peaks exceeded 0.99.
• Computed heart rates (HR) from the pen showed accurate correlation with reference ECG signals.

Conclusions:

• It is feasible to accurately predict heart rate using the accelerometer in a commercial smart pen.
• This demonstrates a novel, non-invasive application of wearable sensor technology for health monitoring.
• The smart pen offers a promising alternative for accessible and routine heart rate tracking.