

Chapter 1
The smart ring revolution
Chapter 2
Smart patches and the sweat whisperers
Chapter 3
Threads with a pulse
Chapter 4
Hearables and the secrets of the ear
Ch 1 · The smart ring revolution

futura While smartwatches sit on bony wrists, smart rings hug digital arteries to let optical sensors measure heart rate variability and oxygen levels.
Quiz
Why do smart rings often get more accurate heart rate readings than wrist-worn smartwatches?

futura Finger-worn health sensors monitor body heat patterns to estimate deep sleep cycles.
Quiz
How small of a temperature change can modern smart ring thermistors typically detect?
Quiz
Which sleep stage is most associated with vivid dreaming and tracked by smart rings using heart rate variability?
Fun Fact
Smart ring origin: The first modern smart ring, the McLear NFC Ring, was introduced at the 2016 Rio Olympics to let athletes pay for things with a wave of their hand.
Glossary
photoplethysmography (noun)
An optical technique used to detect volumetric changes in blood flow within tissue by measuring light transmission or reflection. This technology allows finger wearables like the Oura Ring, released in 2015, to track heart rate variability.
An optical technique used to detect volumetric changes in blood flow within tissue by measuring light transmission or reflection. This technology allows finger wearables like the Oura Ring, released in 2015, to track heart rate variability.
Quiz
Which lightweight metal is commonly used for the outer shell of high-end smart rings?
Quiz
What material is typically used for the inner lining of smart rings to protect the sensors and prevent skin irritation?

