In 24-hour ambulatory monitoring, the enemy is not silence; it is noise. The Livenpace HMM1 chest strap introduces a mechanical variable known as Triboelectric Noise.
The Friction Generator
As you walk, breathe, or turn over in your sleep, the fabric strap rubs against your skin and clothing. This friction generates static electricity (triboelectric effect). Because the ECG sensors are high-impedance inputs, these static discharges appear as sharp, high-amplitude spikes in the data stream.
To an AI algorithm—or even an untrained human eye—these sharp spikes look remarkably like the R-waves of a heartbeat, or worse, the chaotic spiking of Ventricular Fibrillation.
The “Sleep Slide”
The HMM1 is touted for sleep monitoring. However, gravity works against the strap. When a user rolls onto their side, the chest strap often shifts or lifts off the skin momentarily. This “Electrode Lift-Off” causes the baseline of the ECG to wander wildly or flatline.
The AI sees this gap and may interpret it as a Pause or Asystole (heart stopping). Users then wake up to a terrifying report saying their heart stopped for 4 seconds during the night, triggering panic and unnecessary ER visits.
Engineering Verdict: Strap vs. Pad
The chest strap is convenient and reusable, but it is mechanically noisy. For any recording intended to diagnose specific medical issues, the adhesive electrode method (sticking the device directly to the chest) is mechanically superior. It couples the sensor to the skin, moving with the skin rather than rubbing against it, thereby eliminating the majority of triboelectric artifacts.
