Current Status and Prospects of Health-Related Sensing Technology in Wearable Devices

Table 1

Sensors and their health-related functions in wearable devices.

Sensor	Functions
Accelerometer	Step count/calories/pace and distance/active time; Sleep efficiency/sleep time/sleep stages (light, deep, REM); Exercise recognition (walking, running, rowing, swimming, etc.)
Optical sensor	Heart rate (at rest, during exercise) from photoplethysmogram (PPG); 24 h continuous heart rate; Respiration; Oxygen saturation (SpO2); Heart rate variability (HRV); Light intensity (illuminance)
Electrodes	Electrocardiogram (ECG); Bioimpedance analysis (body fat, muscle, etc.); Heart rate (impedance plethysmography); Perspiration