Biostrap utilizes a clinical-quality PPG sensor with RED and InfraRed LEDs, whereas FitBit (and most of the other wearables) use GREEN LEDS.
Red & IR are capable of penetrating much deeper into the tissue which helps us get very high-definition pulse waveform. Another advantage of infrared light over green is that it is less sensitive to skin tone variations and perfusion levels due to its better tissue penetration characteristics. In fact, most of the medical-grade devices use similar technology.
We use the high-definition pulse to derive various vital biometric markers using complex patented algorithms. Currently, we capture Heart Rate, Heart Rate Variability, Respiration, and Oxygen Saturation, and more to come in near future.
Green LEDs on the other hand, are more resilient to motion and light exposure, therefore can read active HR. But can not penetrate deeper, and therefore can’t gather biometric data at the accuracy Biostraps' red and NIR optical sensors can.
So it is a trade-off between getting accurate biometric reading versus active HR. We do, however, offer two types of heart rate monitors, which you can use to measure active HR during your workouts.