Shelten Yuen, vice president of research at Fitbit says that the improved setup yields an average signal to noise ratio increase of 56% for running exercises. It means that Fitbit can now use 6 independent optical channels across a larger surface area to improve the reliability of the data.ĭr. It's achieving that by increasing the number of light transmitters and receivers that are used to get that data. Naturally, while every company dabbling with this optical sensor technology is working from the same blueprint, the accuracy of the readings will come down to how each company's algorithms interpret the data.įitbit's Versa 3 and Sense watches ushered in PurePulse 2.0, which aims to improve the performance of that sensor technology. These lights are then flashed hundreds of times per second to gain the most accurate BPM (beats per minute) data. When your heart beats, this flow, and as a result, the green light absorbed is greater.

So by using green LEDs and pairing them with photodiodes, Fitbit uses its own in-house PurePulse technology to detect the amount of blood flowing through the wrist. Photoplethysmography essentially works upon one simple premise: blood is red because it reflects red light and absorbs green light.

Fit bit versa 2