heart rate is how many times your heart beats per minute. pulse rate is how many times per minute arteries expand because of heart beating. usually same but occasionally medical complications.
2 ways to measure HR
- Electrical - electrocardiography
- Optical - photoplethysmography
- use infrared light to see the expansion of arteries (pulse rate) general - use green light
- hemoglobin absorbs green light well
- green light (wavelength ~525-560nm) doesn’t penetrate deeply ⇒ surface capillaries (clearest pulse signals)
Need: green LED