Fitbit patents a smart ring: what it’s for

Fitbit has filed a patent for a smart ring that, among other things, is capable of detecting SpO2 with an incredible degree of accuracy

Patents aren't always used by the companies that file them, but if the one recently approved at Fitbit goes from the presses to the production chains, it would be a small revolution. The company known for smartbands, fitness trackers and smartwatches, which passed under the control of Google at the end of 2019, has patented a ring with great potential.

Fitbit's smart ring stands out for its ability to monitor the oxygen saturation in the blood - a parameter known by the acronym SpO2 - in a considerably more precise way than almost all technological gadgets that offer this possibility. In fact, the patent of the American company provides a measurement system superimposed on that of medical equipment, a solution that for construction reasons is not possible to apply on other smart objects such as smartwatches or smartbands that also offer this type of measurement. To tell the truth, a similar object already exists, the Oura Ring, but it is not capable of detecting SpO2 and has a few more limitations than Fitbit's patented product.

The precise measurement of SpO2

The main strength of Fitbit's smart ring lies, as mentioned, in the measurement of oxygen levels in the blood with a degree of accuracy that, on paper, could even be comparable to medical devices. Over the past year and a half, SpO2 has proven to be one of the key parameters in the rapid diagnosis of Covid-19 disease, but regardless of the evolution of the pandemic it remains a very important indicator of health status.

The Fitbit smart ring is able to indicate very accurately the levels of oxygen in the blood thanks to the measurement system: the instruments used in medicine, the pulse oximeters, are applied to the fingers or earlobes because they perform the measurement by passing light through the tissues and blood vessels, light that is then received and analyzed by a photodetector on the opposite side.

Based on the fact that oxygenated and deoxygenated red blood cells react differently to light waves, the instrument accurately calculates the amount of oxygen in the blood by analyzing the light hitting the photodetector. Wrist-mounted detectors such as fitness bands or smartwatches, on the other hand, must work differently by deducing the SpO2 value from the light reflected from the skin and vessels in the area where they are applied, resulting in less accuracy than a pulse oximeter or, potentially, Fitbit's smart ring would have.

The advantages over Oura Ring

The patent filed by Fitbit explains how the smart ring can work exactly like a medical pulse oximeter. Compared to the main (and almost unique) competitor, the Oura RingĀ (in the opening photo) which, moreover, is not capable of tracking SpO2, Fitbit's product has another advantage: it has a motion sensor thanks to which it can understand when the subject wearing it is stationary, thus limiting the detection of vital parameters to those moments, when the accuracy of the readings is greater than it would be with the subject in motion.

It's still unclear if Fitbit's smart ring will ever go into production, and moreover it currently doesn't even have a name. The idea is there though, and it's undeniably interesting.