Hardware teardown
A visual tour of the ECG electrodes, NTC temperature sensor, motion chip, radio, battery, and seals that turn a quiet wristband into a continuous stream of health signals.
Exploded view centered
Electrical rhythm
A single-lead ECG records tiny electrical differences across two contacts. Optical PPG watches blood-volume changes with light. Both can estimate heart rate, but they measure different physical events.
Compare signal source
ECG: electrodes detect the heart's electrical depolarization. The sharp R peak is easy to time, but clean contact matters.
Contact temperature
NTC means negative temperature coefficient. The sensor is not a tiny thermometer with a liquid column; it is a resistor whose electrical behavior changes predictably with temperature.
Inertial motion
Inside a MEMS accelerometer, a microscopic proof mass shifts on silicon springs. Capacitive plates translate that movement into three acceleration channels.
Detected peaks
Peak detection: a step is counted when the filtered motion signal crosses a threshold, then waits through a short cooldown to avoid double-counting the same stride.
Spec decoder
These labels describe engineering constraints. They are useful, but each has boundaries that marketing shorthand can hide.
Tested against pressure equivalent to 50 meters of static water. Suitable for swimming and showers when seals are intact.
It is not a 50-meter diving guarantee. Fast water jets, impacts, heat, soap, and aging seals create different stresses.
A low-energy radio link that moves summaries and settings between the wristband and a nearby phone.
Newer controller features can improve power management and coexistence with busy 2.4 GHz networks, but range still depends on antenna and enclosure design.
Magnets align spring contacts with sealed charge pads, avoiding an open USB port in the tracker body.
The contacts need to sit flat and clean. Sweat residue or a shifted puck can interrupt charging even when the magnets appear connected.
Signal check
Five questions connect the component names to the physical signals they actually measure.
Choose one answer in each row.