Since very few smart rings are actually being sold, it's hard to know exactly what's inside these finger-mounted devices, but we do have some clues.
The backbone of every smart ring is Bluetooth technology. Bluetooth is a close-range wireless technology that allows any two Bluetooth-enabled devices to communicate with each other as far away as 328 feet (100 meters) [source: Bluetooth]. You've probably seen hands-free Bluetooth headsets that let you make cell phone calls without actually holding the phone. Like those headsets, smart rings contain a Bluetooth chip, which is really a small radio that can transmit and receive signals from nearby devices.
Like many Bluetooth-enabled devices, smart rings need to be paired with a smartphone to work. Once your phone recognizes and pairs with the smart ring, the two devices can talk to each other. Bluetooth makes it possible for smart rings to function as notification devices, and also as remote controls for Bluetooth-enabled devices and appliances.
Bluetooth is considered a low-power technology, but it still needs juice, so smart rings must contain some type of battery that can be recharged using a docking station or a wireless recharging pad.
In a futuristic twist, some smart rings use finger-pointing gestures to control Bluetooth-enabled devices. Point at the TV and draw a power button in the air to turn it on. Swipe your finger to the right to advance to the next slide in a PowerPoint presentation. For gesture-based devices, the smart ring must not only contain a Bluetooth chip, but also some kind of motion-sensing engine. The motion-sensing hardware and software detects the real-time position of the ring and sends that data via Bluetooth to the target device.
What you won't find on most smart rings is a screen. Yes, there are a few prototypes with a fingernail-sized display, but the whole point of a smart ring is not to stare at it like your phone. Without a screen, though, smart rings rely on smartphones as the chief way to program and interact with them.
That's why all smart rings comes with an associated smartphone app. The in-phone app is how you can customize the smart ring's settings and configure it to update you with notifications from other apps such as Twitter, Instagram, email and calendars.